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Peter Lewin
14-Sep-2016, 14:09
My frustration with "hit or miss" corner adherence (if that is a word) has reached the point of asking for help! I used to love MT-5 which adhered under heat; I have a love-hate relationship with the Archival tissue which adheres during the cooling cycle. (I could probably just change to Colormount which I think is also heat-adhering, but at least philosophically I like the archival idea.)

First: equipment - I have a Seal 110s press, which has the 12x15 platten. I'm mounting 11x14 trimmed prints (so they are slightly smaller than the nominal size) which obviously doesn't leave a lot of leeway in placement in the press, but I try to be careful and make sure that the platten covers everything. The problem I'm having is that randomly I get one or more corners not sticking. I've tried a variety of approaches (please bear with me, just trying to provide as much info as may be relevant).

Originally I would sandwich the mount board (2-ply) and tacked print in-between two more pieces of 2-ply, and when I removed the mounted sheet, quickly place it under a heavy glass sheet (since I never owned a proper Seal "iron plate," the 20x20 is currently listed as special order at B&H, $280). I experimented with temperature and time, and no matter what, got inconsistent results.

Since I never had a problem tacking the mount tissue, I thought I would try to see how close I could get to that approach. So I tried taking the top 2-ply off the sandwich and just using a sheet of interleaving tissue between the print and the platten, set the temperature to 175 for about 1'15", and then placed the mounted print under an aluminum baking sheet with filled 1/2 gallon containers as weights. Again, inconsistent results - sometimes good, sometimes the unstuck corners. Admittedly the baking sheet is again just slightly larger than the trimmed print.

So: would appreciate thoughts on technique, and perhaps a better idea for the cooling weight if the problem is that everything is so close to the print size so that placement has become too critical. Admittedly I get good mounted results if I go through multiple cycles for each print (i.e. keep trying until it finally works) but there must be a better way!

Phil Hudson
14-Sep-2016, 14:24
Maybe the press is not so hot in the corners?

Kirk Gittings
14-Sep-2016, 14:53
First I would pre-heat the mat board to drive any moisture out of it. Moisture is the enemy of dry mounting. For a cooling weight I use a sink cut out from a granite counter top. I got mine for like $5 from a stone counter company. To move it around securly, I then epoxied a 1x4 onto the the rough side and screw a couple of handles to that. That granite sucks the heat right out of a dry mounted print/mat board and keeps the edges down.

Erik Larsen
14-Sep-2016, 15:31
If you're not in a hurry, just leave it in the press till it's cooled enough to set up. I've done that for years but if you have many prints to mount it isn't too practical. If the corners still lift after that I would look at my bottom foam pad to see if it isn't making good contact like the center is.

Drew Wiley
14-Sep-2016, 16:17
"Archival Mount" is for low-temp application, and might indeed fail just from storage on transport in a hot climate, while MT5 in intended for a relatively hot press. I use Colormount, which is in between. But it's a combination of "dwell" time under pressure in the heated press and the actual temperature, which must be sufficient to begin with, and won't be unless you keep your press shut when not actually placing or removing things from it. Over time the thermostats can misread, so you might need to check the accuracy on your with a Seal melt test kit. And then there's basic technique, including properly predrying everything just before bonding. Some of these adhesives finally set under the cooling weight rather than in the press. I use a big sheet of heavy plate glass. Don't test the corner bond by flexing the board until it has thoroughly cooled first.

Drew Wiley
14-Sep-2016, 16:24
Oh, there's nothing more "archival" about Archival Mount than other regular tissue choices. That label simply means, 1) The print can be removed later by re-applying heat, and 2) it is pH buffered distinctly alkaline, which is not in fact a good thing for every photographic print media. Regular tissue might do a better job simply by isolating the print chemically from the mountboard; and even this is redundant given the fact that most of us use stable Museum Board to begin with. I notice Wilhelm's old literature complains that drymounting prevents prints from being scanned, along with a picture of an ancient drum scanner the size of a washing machine. Now we (or rather, serious pre-press shops) have excellent repro-grade flatbeds, or maybe scanning copy cameras, capable of handling big flat originals, even attached to museum walls. In other words, I never saw much sense to Archival Mount being marketed to begin with.

John Olsen
14-Sep-2016, 17:08
I'll ditto Kirk's comment about running the mount boards thru the press beforehand to dry them out. I give 'em 45 sec each side with some airing out in between. I also re-dry the prints with two 20 sec heats and airing between.

For the mounting itself on the 110S, I set it for 220, using "buffermount" sheets. Press time is 2' 20". I used to run lower temperature and shorter time but the materials take more time and temperature since Seal sold out to Bianfang and then DK. You can feel the difference between the original Seal material and the newer DK sheets, so it makes sense that the process time and temp will be different.

I use an 8 ply board under the 4 ply that I mount to, a release sheet on top and a 4 ply under the platen. I let the mounted prints cool down for an hour under (dried) matboards with books stacked on top. (Avedon photo books seem to impart the best karma to the process.)

I arrived at these conditions thru trial and frustration.

But, I only mount 8x10s in the 110S. Before I got a larger press for the bigger prints, I would do the 11x14s in two press time: one time for the top half, rotate 180, a second time for the bottom half. I didn't trust the temperature to be even all the way to the edge.

This is fun, no?

John O

Bruce Barlow
14-Sep-2016, 18:09
Yup, I dry out the board beforehand, too.

I have two bricks wrapped in paper. We used to joke about selling them at Zone VI ("Zone VI Bricks. $29.95"). They help keep things flat during the cooling process.

If something doesn't adhere, I just put it back into the press for another minute or two. No harm has ever been done, to my knowledge.

jp
14-Sep-2016, 18:50
I've been using Dry-lam colortac dry mount tissue. I've mostly used it for mounting silver gelatin prints, but a couple weeks ago I did some inkjet luster paper mounted on matboard for indoor signs at my gallery. 30 seconds in the press blistered/cracked the inkjet, so 20 seconds was plenty to melt the drymount tissue and not destroy the printout! I have an older Seal jumbo 150 press.

LabRat
14-Sep-2016, 19:32
+ 1 on using a slightly higher temp... For standard dry mt tissue, it is about 225deg... (It it bubbles, it's way too hot!!!) Letting it cool slowly while it's in the mattboard/release paper "sandwich" (for a couple/few minutes) until it sets is a good thing...

But also remember, that nowadays, curators tend to frown upon dry mounted prints, as they can be risky to change-out the matt backing way down the road, and prefer the print is hinged with museum tape along the top edge... The curl is pressed down with the overmatt, and if the print is not overwashed and is flattened correctly, it will usually stay put well...

Steve K

Kirk Gittings
14-Sep-2016, 20:13
But also remember, that nowadays, curators tend to frown upon dry mounted prints, as they can be risky to change-out the matt backing way down the road, and prefer the print is hinged with museum tape along the top edge... The curl is pressed down with the overmatt, and if the print is not overwashed and is flattened correctly, it will usually stay put well...

Steve K

FWIW I have over 200 prints in museum collections-most of them purchased from me-almost all of them dry mounted. Not once has any curator mentioned an issue with dry mounting. Not even a single word on the subject in 38 years. The same goes with sales to public art programs.

LabRat
14-Sep-2016, 20:29
FWIW I have over 200 prints in museum collections-most of them purchased from me-almost all of them dry mounted. Not once has any curator mentioned an issue with dry mounting. Not even a single word on the subject in 38 years. The same goes with sales to public art programs.

I have done work in museum services... Sometimes an issue has come up when they are faced with a print that can't be released from the decaying mount, that can't be exposed to the conventional release methods... (Like paste mounted dye-transfers with vermin eaten rotting mounts that can't be soaked off etc...) But true, most modern standard DWFB's heat mounted can be re-inserted into a press and "popped" off later, so less sweat... But some curators are aware that if an important work's mount has been damaged by the usual suspects, there are options they would rather not use (if possible)...

Steve K

Mrportr8
14-Sep-2016, 21:31
If you are mounting fiber base prints then MT-5 would be fine but I would recommend you try Drytac Trimount. It is a solvent acrylic heat activated adhesive. Archivalmount is a polyethylene thermoplastic and only offers a mechanical bond which is not strong enough to hold the corners in many cases. The same is true with D&K which is a thermal plastic. The key is to find the temperature setting that activates the adhesive and sets quickly before the corners have a chance to pop. Thermal plastics have have a very short cooling off period and loose tack almost as soon as you remove them from the heat source. Solvent acrylics bond as they heat up and have a longer cooling off period during which they remain tacky enough to keep the corners bonded. But in either case we're talking about mere seconds and fractions of seconds. Never ever use release boards. They act like insulation and slow the drymounting process. Instead use cover sheets and release paper and place everything in the press at once as a sandwich. Hot cover sheets will begin the mounting process before you even close the press. Drymount press thermostats are notoriuously inaccurate for several reasons which is why testing is important. And it does not take much weight to keep your prints flat. A piece of 1/8" masonite or aluminum is enough. The important thig is to remove the print quickly and place it face down on a piece of clean release paper with your weight on top.

Steve Goldstein
15-Sep-2016, 03:54
But, I only mount 8x10s in the 110S. Before I got a larger press for the bigger prints, I would do the 11x14s in two press time: one time for the top half, rotate 180, a second time for the bottom half. I didn't trust the temperature to be even all the way to the edge.

John O

When you use this two-pass technique do you cool the first half under weight before heating the second half?

Doremus Scudder
15-Sep-2016, 05:06
I use BufferMount, or whatever it's called now with great success. In 35 years I've had about three prints that have had problems and those got remounted.

Here's my technique FWIW:

First, I don't use weights; it takes too long to lay the print down and get weight on it. After the boards have been dried previously in the press, I tack the print to the board. The press is heated and has a 4-ply board and a sheet of cotton-rag 1-ply interleaving in it heating with it. The press gets opened, one hand lifts the interleaving sheet and the print slides in between the board and the 1-ply (with the one ply on top). The press is then closed. After the requisite time (do test for this), the print is removed together with the sandwich of board and cover sheet. It slides out quickly onto the flat counter top at which time I use my cotton-gloved hands to press the print to the board while it's cooling. I pay attention to the corners and edges. After about a minute of cooling, I give the mat board a twist in both directions. if the print pops off anywhere, it goes into the dry-mount press again and the process is repeated. After a while, you'll get the right technique down and not have to return any prints to the press. This works fine for two-pass mounting as well.

The advantage to using the removable tissue is that mistakes can be easily corrected. For example, if the print is improperly positioned or the board later gets damaged. I've removed and mounted several prints (largely due to my mounting mistakes, i.e., getting the borders wrong) with 100% success. The board the print is removed from is no longer usable (unless you can cut a window mat from it), but the print mounts fine with new tissue.

FWIW, I sign all my prints lightly with pencil on the reverse before mounting so that, in the event that they ever need remounting by the owner, the provenance will be clear.

I've never tried the DryTac Trimount product, but after a quick perusal of their website, find the product interesting but it doesn't seem to be removable. I think I'll stick with BufferMount just for that reason.

Hope this helps,

Doremus

bob carnie
15-Sep-2016, 07:02
I am on the fence and I see both points.

I prefer mounted prints any day of the week, I absolutely hate seeing wavy prints

But I just delivered a show of silver prints that were not mounted as per request of the Gallery , other than the two very large murals that needed to be mounted.



Today I give super wide borders on any silver image, and I mount to a 2 ply rag using current heat tissue. this seems to work well for my work.

I remember going to Light Impressions in the late 70's and seeing an Ansel Adams show where all the edges, or most were lifting or chipping, he cut the window matt around a flush mounted print for his signature.

That was enough for me to stop mounting and presenting work this way, in fact it was the standard method at my college to present work.

John Jarosz
15-Sep-2016, 07:41
I simply don't like the look of unmounted prints overmatted at the edges. Plus, carbon prints usually have thicker gelatin than silver and they curl much more than anything else.

I have a Seal press that is smaller than my 8x20's. With the old style tissue I never had any problems mounting oversize prints by releasing the press, moving the print, reclamping etc. That technique doesn't work with this new 'archival' stuff. Even with prints that do fit in my press I do not like the way the new stuff works, I always feel it will release at some point in the future.

What is the mount tissue that is the closest in performance and workflow to the 'old' style mount tissue? It's fine if it's permanent - I don't care what curators think.

There are times when change is bad. This is one of them.

Drew Wiley
15-Sep-2016, 08:53
I haven't had a bonding failure in decades, nor a print ever damaged in the process. I have used Colormount the whole time (at least for typical fiber-based silver gelatin paper), museum board, and the same big 500T Seal press. I am familiar with the other tissue options as well as both wet mounting and various kinds of aggressive adhesive bonding, and know when to hypothetically use them. Drymounting is far easier. And I already stated why a buffered version or tissue is utterly redundant. My specific technique is a little different than most. I have demonstrated it in my lab to others, but could if necessary describe it. But pre-drying (without overdrying and making the emulsion brittle, or the board downright hot) is critical to any of these. There is a picture in Wilhelm of a cracked AA drymounted print due overdrying, along with careless transport. Well, badmouthing drymounting due to something like that is like telling people to never drive a BMW because someone once ran into a tree with one. The print would have been ruined regardless, due to crease marks at a minimum; and for
all I know, Ansel or one of his assistants might have been using a press with a bad thermostat. But for the record, he used Colormount too, and I've never heard
an instance a curator turned down an AA print for either display or collection because it happened to be drymounted!! ... or anyone else's prints for that reason.
There are certain photo media like Pt/Pt on rag paper which are more esthetically pleasing tipped-in or hinge-floated like a watercolor painting rather than
drymounted, as well as certain medium like albumen and dye transfer which are actually damaged by alkaline buffering. Nonbuffered board is made for these
too. Sometimes "archival" CaCO3 buffering is just a marketing trick for selling otherwise inferior matboard or mounting board.

Michael Rosenberg
16-Sep-2016, 09:08
I echo what Kirk said. Preheat the print and board. Living in the humid south can affect print adhering, so I run a dehumidifier when it is humid, and a humidifier in the winter. The helps too with print storage.

I use color mount also, and had done a time/temp study to find the proper settings. I have one of the older 220 presses that is silver, and no temperature gauge. Too high a temperature will affect the print. So test to get the right ratio.

I once spoke to somebody at Seal (when it was still Seal) and they said the newer presses did not heat evenly, and never trust the thermometer on the newer presses. When Seal/Bienfang was purchased by Elmers the mount tissue changed. I have heard from many people that the newer material does not work as well, and they have had to change to another tissue. I found that when I switched to the new color mount I had to increase the time. I have had the edges not adhere, but never been successful sticking the print back in and getting it to stick.

The other possible cause is the pressure that is applied. Is the pad fairly new, or an old one? I use 4 ply board and have one board on top of the print and two under the print to insure good pressure.

After mounting I quickly inspect the edges to see that they are stuck, and then place the print between two pieces of board then with a piece of birch plywood on top. I then use two 25 lb dumbbells on top of the board and let it cool.

Mike

Drew Wiley
16-Sep-2016, 10:06
The new Colormount is actually made in China, and yeah, given my well-founded suspicion of anything outsourced these days, I'll thoroughly test it on scrap prints
before using it for my good ones. It is branded D&K, along with Seal. I haven't heard any specific complaints yet; but I never trust anything I haven't personally
tested.

Bruce Barlow
21-Sep-2016, 16:38
+ 1 on using a slightly higher temp... For standard dry mt tissue, it is about 225deg... (It it bubbles, it's way too hot!!!) Letting it cool slowly while it's in the mattboard/release paper "sandwich" (for a couple/few minutes) until it sets is a good thing...

But also remember, that nowadays, curators tend to frown upon dry mounted prints, as they can be risky to change-out the matt backing way down the road, and prefer the print is hinged with museum tape along the top edge... The curl is pressed down with the overmatt, and if the print is not overwashed and is flattened correctly, it will usually stay put well...

Steve K

May I someday have the problem of curators worrying about my drymounting...

Leigh
21-Sep-2016, 16:47
I have a Seal 110s press, which has the 12x15 platten.
I'm mounting 11x14 trimmed prints (so they are slightly smaller than the nominal size)
One problem is that the press corners will be cooler than the center.
This is just the way such heated devices work.

The only way to cure it is to increase the thermostat setting to get the corners hotter.
Of course, that makes the center significantly hotter.

- Leigh

Leigh
21-Sep-2016, 16:51
The new Colormount is actually made in China, and yeah, given my well-founded suspicion of anything outsourced these days, I'll thoroughly test it on scrap prints before using it for my good ones.
Testing won't tell you anything except possibly about the specific package you're working with.
That information won't carry over to any other package of the same product.

The problem with products from certain countries is that they have absolutely zero quality control.
Whatever comes off the end of the production line ships out the door.

- Leigh

Willie
21-Sep-2016, 19:27
Why not go back to what worked for you before the change?

In addition, get a larger press so the image is centered and the print edges get more even heat?

LabRat
22-Sep-2016, 04:55
The corner problem might also just be because that area is the most curled (and under more tension) and less supported (they are "points"), and the corner area would cool slightly faster, so if not supported while still hot, that would tend to "lift" easier than the body of the print... I think letting it sit for a bit while still in the "sandwich" to cool a little longer, and pre-flattening the prints well before mounting would help, and try to notice if the issue happens more or less during differing humidity conditions to see if moisture is a culprit...

Good Luck and nice prints to 'ya!!!

Steve K

Jim Jones
22-Sep-2016, 06:55
Testing won't tell you anything except possibly about the specific package you're working with.
That information won't carry over to any other package of the same product.

The problem with products from certain countries is that they have absolutely zero quality control.
Whatever comes off the end of the production line ships out the door.

- Leigh

I agree that certain countries have a "monkey see, monkey doo-doo" approach to production. OTOH, the same countries sometimes produce superb products for their own use. I had problems with Colormount even when it was produced in America with mat boards eventually discoloring around the edge of the image. This is also conspicuously true of a Cole Weston print bought around 1978, although I can't be sure that Colormount or any other heat activated tissue was used.

Drew Wiley
22-Sep-2016, 08:30
Colormount forms its final bond under weight while it is still cooling. Skip that step and you've got a potential problem. Heat under a press platen also tends to
diffuse through the ragboard sandwich, which should have been placed around the actual mount to begin with, and likewise properly pre-dried. But presses themselves should be reasonably consistent over the entire platen. If they aren't, time to junk the machine.

Mrportr8
22-Sep-2016, 09:23
But presses themselves should be reasonably consistent over the entire platen. If they aren't, time to junk the machine.

Due to the heat element design in nearly every press it is impossible for the heat to be even across the entrire platen. The edges act as a heat sink and wick heat away from the center. In general practice you should use a press to match your largest BOARD SIZE not the print size. This would ensure you are within the central area where heat is the most conisitent. Heated glass vacuum presses made previously by HotPress and later by Drytac (after they acquired HotPress Ltd.) avoid this problem by running current over the top of a sheet of glass thereby the glass itself is the heat element. There are still hot spots and cool spots but the variance is far less than a standard wire heat element. A good pratice with any heated platen press is to allow it to heat up and and equalize a while before use. This should be done with the press closed. But even then, the edges will be cooler. Remember, there is a thermocouple embedded somewhere on the platen and its placement determines what spot is measured to cycle the heat on and off. I leave my press on for about 45 mins. at the minimum before I use it.

bob carnie
22-Sep-2016, 09:35
I now have the unit you describe where the heat is form the glass unit above, it works very nice.

I had a 40 x60 press with big platens and it was a nightmare finding spots .

cowanw
22-Sep-2016, 10:38
There is a common understanding that pre heating a mat board de-humidifies it. Warm air can hold more water: apart from everybody repeating the same thing, is there any evidence for this concept of pre drying?

Drew Wiley
22-Sep-2016, 10:57
Yep. Lots of evidence. Yer tissue forms blisters under it cause the moisture can't get thru. Then yer print detaches somewhere. If you don't believe us, then read
any tutorial ever written for frame shop pros or the Seal handbook itself. This is about as standard as claiming you need air in your tires to drive down the road.
No if's, and's, or but's. The only logical exception would be if you work in a desert climate and store your material where the humidity is always very low to begin with. Beyond that, you always do pre-heat a press to the recommended temperature (nice way to warm up the workroom in the winter too), and always distribute the heat via a secondary medium if the work is especially large relative to the press size. I have done very large oversized pieces involving multiple laminations this way. Drymounting is easy and highly reliable once you understand the basics.

Jon Shiu
22-Sep-2016, 11:13
There is a common understanding that pre heating a mat board de-humidifies it. Warm air can hold more water: apart from everybody repeating the same thing, is there any evidence for this concept of pre drying?

Well you can see the water vapor leaving the press when you open it after pre-drying. I guess you could weigh the board before and after to scientifically prove loss of moisture.

cowanw
22-Sep-2016, 12:10
1. ColorMount is apparently formulated to allow water through according to http://www.wilhelm-research.com/pdf/HW_Book_11_of_20_HiRes_v1c.pdf.
Drew, can you share the source of evidence (as opposed to Opinion (which is often simply repeated tutorial after tutorial) or even company literature which is formulated at the level of sales talk).
2. I have never seen water vapour (steam?) coming out of the press. Seeing would go a long way to believing. But of course I live where I live and household humidity is not high. Weighing the board would be good evidence.

Drew Wiley
22-Sep-2016, 13:00
It breathes a tiny amount, not enough to allow you to break the rules. The EVIDENCE is thousands and thousands of successful professionally mounted prints over decades versus "I told you so", or "you're fired, dummy". Museum board is quite hydroscopic. I see steam coming off it 100% of the time. I can hardly image the headache of drymounting in tropical or subtropical climates. And it will reabsorb moisture from the air rather quickly. That's why pre-drying needs to be done just before actual permanent mounting.

Mrportr8
23-Sep-2016, 13:09
There are four variables to control for successful mounting:
Time
Temperature
Pressure
Humidity

A change in any one of them requires a change in the other three. Off all I have come to realize humidity is the least understood and most disregarded. Too much can yield anything from curly mount to poor adhesion and or mottled prints. Anyone who has used a heated vacuum press can attest to the amount of moisture being extracted during the process. It is usually evidenced by droplets of water around the perimeter of the cover sheets, foam overlay blanket, especially near the vacuum tube port. It's harder to detect with a mechanical (clam-shell) press but damp release sheets will indicate the presence of water. It's in the boards and prints. In small quantities it's no big deal, but can be problematic on humid days (especially after several humid days) and in tropical/sub-tropical climates.

Drew Wiley
23-Sep-2016, 13:29
Like I already hinted, some climates are dry to begin with, and some indoor spaces are so consistently heated with forced dry air that they might actually develop
the opposite problem. In such cases, overheating the print might embrittle the gelatin, risking cracks or edge flaking. Another problem with overdoing it, one extreme or the other, is that the print/mount sandwich must reach equilibrium afterwards, and excessive curling is a risk if you're way off. When in doubt, do representative tests in advance, then see what happens over the coming weeks and months. Here we don't have a humid climate in the sense of sticky hot weather, but do have fog much of the year, so f you don't predry all the components, the odds of some kind of eventual bonding failure is close to 100%.

John Olsen
23-Sep-2016, 17:08
When you use this two-pass technique do you cool the first half under weight before heating the second half?
Sorry for the slow reply, I was out torturing some film in the mountains. No, just rotate it and stick the sandwich back in. I do gently support the half that's hanging out so it doesn't flex a lot.

jp
23-Sep-2016, 18:33
There is a common understanding that pre heating a mat board de-humidifies it. Warm air can hold more water: apart from everybody repeating the same thing, is there any evidence for this concept of pre drying?

I generally think well of thoughtful skepticism that mixes questioning and doing. My evidence would be the kitchen or laundry. Heating clothes in the dryer drives the water out by making it easier to evaporate the water. Toasters make bread dryer. Microwaves have vents/fans as water is liberated by the heating.

John Olsen
23-Sep-2016, 19:30
There is a common understanding that pre heating a mat board de-humidifies it. Warm air can hold more water: apart from everybody repeating the same thing, is there any evidence for this concept of pre drying?

If you're concerning about the print staying on the mount, you'll note that the first time you run the board through the press it bends a lot as it cools off. The second time through it bends only a little. And if the third time through, you've actually mounted the print, you'll be pleased to see that it doesn't warp at all. The print is more likely to adhere if it's not on a flexing mount.

I live in a humid climate - you can really feel the moisture steaming off the mount board on that first pressing! But hey, do whatever you like.

cowanw
24-Sep-2016, 11:28
Jp, I was going to leave it. But your kindly answer deserves a response. Your dryer example accelerates evaporation based on a large volume of warm air passing over the damp surface, providing an interchange between the water and board which will be cooled by the evaporation until an equilibrium is reached where the air supplies the amount of heat removed by the evaporating water. In an enclosed environment the water would evaporate until the air is saturated. The space between the mount board and the platen or other boards must be very small (the whole point is contact and pressure) and would be saturated very quickly. It is the large volumes of warm air that accelerate evaporation in the example of a dryer.
The toaster (likely) and the microwave (definitely) boil the water and create vapour within the water once 212 F is reached locally.

John, if you are seeing steam then you have heated the water to 212F and are far beyond the 175 to 200 recommended for current mounting tissue (according to Seal). Likely here you are seeing fog. That is to say an aerosol of microscopic water droplets suspended in the air after the water vapor has cooled and condensed.
Which certainly does suggest some water is coming from somewhere.
My question is from where and how much. Does the entire 1/8 inch board transfer its humidity to the less than thin space of air between the board and platen? Does it travel 4-8 inches along the plane of the board to exit out the edges?
If heating the board dehumidifies it, does cooling it, suck water into it?
If the board is very hydrophilic why isn't the effect of immediate post press, a process of dehumidifying of the tissue/board interface as the thickness of the board sucks water back into it?

Wilhelm research doesn't really provide a reference to it's mounting procedure but does heavily quote Adams throughout the chapter (which doesn't inspire a sense of evidence over opinion)

I have a stock of pre 1930 waxed mounting tissue, and type one and type two mounting tissues and they all require different temps and time. changing materials and techniques must have required process changes.
Any way, I am not saying that preheating is not important or that I don't do it. I am just wondering if some 1930's print mounting guru declared preheating is important and it has morphed into " to dehumidify it " and has been repeated by experts repeating experts; or has anybody actually shown scientifically that this is true.
On the other hand I am aware enquiring minds likely don't give a damn.
In a not unrelated thought here is a post of the history of Dry mounting.
http://cool.conservation-us.org/coolaic/sg/bpg/annual/v12/bp12-15.html
It is total coincidence that We have the same post script, her's found just before the glossery.

Robert Opheim
24-Sep-2016, 13:50
I had problems with dry mounting 16x20 and 20x24 prints and having the dry mount paper releasing from either the print or the rag board. I found finally that I was not putting enough weight on the mounted print while it was cooling. In the past I had a extra press that I would put them in. I looked on line and the Seal weights are really expensive and expensive to ship. I went to a local welding shop and had them put one together for me 25"x30" - as the largest I am printing right now are 20x24 prints. My weight is made from 3/16 inch plate with two steel strap handles.

Duolab123
3-Oct-2016, 20:30
I always use a plate of aluminum I picked up somewhere as a weight to press and to cool the print seems to really help
adhesion. Dry board too, I've heard people suggest leaving large 4 ply mount board in a oven overnight at 170F.

Mrportr8
7-Oct-2016, 07:27
Here is how you dry your boards, if necessary.

Mechanical/ clam shell press
Set the press for 195 F and let it warm up for 30 minutes to stabalize. Place the board to be dried in the press between release paper and close the press but do not lock down the top. After one minute open the press and flip the board over and close the top, again not locking it. Repeat this cycle for 5 minutes then remove the board and place it under weight to cool.

Heated vacuum press
Set the press for 195F and allow it to heat up and stabalize. Presses vary so this can take anywhere from 15 minutes to 30 minutes. Place a sheet of kraft or butcher paper in the bottom of the press and place your board/s on top. Cover with release paper and close and start the press for a ten minute cycle. When finished, remove the board and place under weight to cool. The butcher paper will absorb moisture so you don't end up with condensation in the press. And no, the paper will not discolor your board unless it contains dye, in which case you have the wrong kind of paper.

I have used both of these methods for over 30 years and have never experienced any issues related to moisture. Being in Chicago this process was only required in the summer on very humid days. Even though our shop is air conditioned humidity does still fluctuate. That's why museums have carefully controlled envirnments for their collections. They keep relative humidity and temperature within a controlled range to protect their precious collections stable.

Drew Wiley
7-Oct-2016, 08:16
A couple points I'd add: Preheat the press to the correct temp you need for final tissue bonding. That will also dictate how long you need to predry. I only predry
each sheet of board less then 30 sec per side, even in this damp climate, at my typical bonding temp of 220F. Second, I always predry my mount between two
sheets of similar museum board, themselves pre-dried first. These sandwich sheets can obviously be a bit blemished and used repeatedly, provided nothing is
embedded in them which will dent or contaminate your official mounting piece. Kraft paper and other ordinary papers or board inherently run the risk of contaminating your mount, so cannot be recommended for anything of alleged archival value. Yet another warning: Release paper should never be used directly atop an actual print emulsion. That ingredient can transfer too, and create an irremovable shiny spot. It's only intended for the back of the paper to front of the
mounting board.

John Olsen
7-Oct-2016, 20:34
Yet another warning: Release paper should never be used directly atop an actual print emulsion. That ingredient can transfer too, and create an irremovable shiny spot. It's only intended for the back of the paper to front of the mounting board.

I'm sorry I don't understand this. I thought we make a sandwich of backing board, print (with dry mount tissue tacked on) face up, release paper, top board and then the top plate of the press. What do you mean here? I'm with you on the rest.

Mrportr8
9-Oct-2016, 09:28
Kraft paper is perfectly safe for use in contact with rag board. It's used for absobancy so moisture has somewhere to go. Any acidity will not transfer to the mount board, especially if it's buffered board. And silicone release paper is not going to create problems. Without it you do risk having any exposed drymount tissue attach itself to to your cover sheets. The shiney spots you saw were caused by too much heat and too much pressure. A 30 second dwell time even at 220 F is too short to dry any more than the outer surface of the board. It's the moisture trapped deeper within the board that is a problem. If your prints are not completely dry you will also see mottling appear as moisture tries to escape from the emulsion. In the case of inkjet prints, you must especially be certain they are completely dry. Inks form a dry film over still wet or damp ink. It will take up to several days for this "jelly bean" to dry completely. If you use a product like Drytac Trimount it will activate at 195 F which is safer for inkjet. Likewise, some of the thermoplastic prducts like those offered by D&K can acrivate at even lower temps and would be easier to use with inkjet.

Mrportr8
9-Oct-2016, 09:33
I'm sorry I don't understand this. I thought we make a sandwich of backing board, print (with dry mount tissue tacked on) face up, release paper, top board and then the top plate of the press. What do you mean here? I'm with you on the rest.
You are correct.
From the bottom up
Substrate
Adhesive
Print
Release paper (never release board)
And a top layer of one or two cover sheets

The top couple of cover sheets help to slow the actvation of the adhesive so it heats more gradually. This allows any additional moisture or air a chance to escape before the adhesive activates. The last consideration is pressure, you want the press (mechanical clam shell type) to close with a slight snap but without requiring brute force. We want even pressure and not an attempt to emboss the print into the substrate.

Drew Wiley
10-Oct-2016, 08:51
Do you have any idea what Kraft paper exactly is? There are usually a couple hundred rolls of it in inventory here, along with certain other archival felonies that we periodically sell in volume to quickie art events which I'm hesitant to mention, including museum surplus print fundraisers. Sends shivers down my spine.
Run a pH pen across it. Now about release paper - I never let it touch the emulsion heated. I tack it and press the mounting tissue to the BACK of the print using the minimal time to secure it without any wrinkles, in the normal sandwich of ragboard and release paper behind the print. AFTERWARDS, after cooling this under weight, I then trim the print on the cutter to final size, with the tissue itself also automatically being precisely trimmed to the final image diameter. Then the final pressing, onto the final mount, with no release paper needed. I've demonstrated this method to others, and so far they definitely prefer it. No slippage of the mounting tissue or funny tack one spot to the print, another to the mount, then hope. Don't want to elaborate too much, but release paper is really just silicone treated glassine, and eventually wears out, or in a worst-case scenario, will transfer a tad of silicone to the face of the print, leaving a blemish almost impossible to remove. But if I were paying someone to mount my prints instead of doing it myself, and they claimed to be doing archival work, I'd walk out the
door if I saw Kraft paper in use. Anyone duly educated would.

bob carnie
10-Oct-2016, 12:29
funny I just talked to my rep about pre drying boards, and he suggested Kraft , which I immediately raised concerns, we do not even use kraft as backing for framed pieces.

He then suggested cotton sheets as a way of transferring moisture, I will give this a go , I wonder if my wife will miss a couple.

Drew Wiley
10-Oct-2016, 12:45
It's not just the acidity of Kraft, but the fact that the manufacturing standards, including the mfg facility itself, are not oriented to these kinds of fussy uses. I always use oversized pieces of actual museum board. These can be reused as long as they are kept clean of contaminants, especially those little bits of drymount press foam that get embedded from time to time. Kraft is thin, so anything like that might create and dent mark in the emulsion. Thin versus thick also means heat is distributed less easily. And of course, I already noted the risk of contamination from unknown ingredients, not just acidity. Mere buffering as a mount board does not solve all this, and in certain instances tends to be a marketing ploy for classifying a cheap board as archival. For some media, alkalinity is a bad thing anyway. I've interacted with some of the museum display facilities around here, and they are mighty nitpicky, anal, specific - whatever you want to call it. The conservators call the shots. It's a totally different ballgame from a community art venue asking for bottom dollar mass production technique, even if the proceeds go to the museum. Even a different facility. I should know. I sold the actual museum most of their gear. Even the leading production framer in northern Cal is very specific about the classification of the frame job. Nobody wants to get sued over an expensive contract that took shortcuts in archival methods. It's a whole different ballgame than do-it-yourself frame shops of the kind in shopping malls; and even they better know the difference if they expect
to stay in business long.

Mrportr8
11-Oct-2016, 06:58
Do you have any idea what Kraft paper exactly is? There are usually a couple hundred rolls of it in inventory here, along with certain other archival felonies that we periodically sell in volume to quickie art events which I'm hesitant to mention, including museum surplus print fundraisers. Sends shivers down my spine.
Run a pH pen across it. Now about release paper - I never let it touch the emulsion heated. I tack it and press the mounting tissue to the BACK of the print using the minimal time to secure it without any wrinkles, in the normal sandwich of ragboard and release paper behind the print. AFTERWARDS, after cooling this under weight, I then trim the print on the cutter to final size, with the tissue itself also automatically being precisely trimmed to the final image diameter. Then the final pressing, onto the final mount, with no release paper needed. I've demonstrated this method to others, and so far they definitely prefer it. No slippage of the mounting tissue or funny tack one spot to the print, another to the mount, then hope. Don't want to elaborate too much, but release paper is really just silicone treated glassine, and eventually wears out, or in a worst-case scenario, will transfer a tad of silicone to the face of the print, leaving a blemish almost impossible to remove. But if I were paying someone to mount my prints instead of doing it myself, and they claimed to be doing archival work, I'd walk out the
door if I saw Kraft paper in use. Anyone duly educated would.

I know what kraft paper is. My special area of expertise is mounting, laminating and framing. It's too easy to become paralyzed with so much information that legend becomes fact, even (especially) among conservators. Again, there is no transfer of acidity from kraft paper in the few minutes it takes to dry a board. Now, I would not propose leaving kraft paper in contact, like in a frame, for long periods of time; years.
As for silicone transfer; for this to occur your press would had to have been in excess of 300F. There are two methods of coating silicone to paper, BTW they use kraft paper, usually bleached. The two methods are UV curable and hot melt. The latter being the most widely available, it can easily withstand normal temperatures used in our process. I suspect you had either defective paper or it was coated with something else, perhaps lacquer. Or, more likely what you experienced was mottling due to uneven release of moisture through the print surface. This would cause something akin to ferrotyping where some areas offset the smooth surface of the release paper and others were matted due to outgasing of moisture.
Having said all of that and reading all the responses to the original post it is evident that just like with film processing there is a certain amount of paralysis by analysis. Mounting is easy!

cowanw
11-Oct-2016, 07:29
funny I just talked to my rep about pre drying boards, and he suggested Kraft , which I immediately raised concerns, we do not even use kraft as backing for framed pieces.

He then suggested cotton sheets as a way of transferring moisture, I will give this a go , I wonder if my wife will miss a couple.

What do you use for backing for framed pieces, if you please?

bob carnie
11-Oct-2016, 08:36
What do you use for backing for framed pieces, if you please?

Right now Yupo or rag paper if I can find large enough pieces.

Drew Wiley
11-Oct-2016, 08:36
My approach is very efficient in terms of time and materials, but also has a "better safe than sorry" protocol embedded in it. I have never used temperatures even remotely approaching 300F, and all the release material I have even used was consistent Seal brand. And no, ferrotyping was not an issue. And no again, there was no resemblance to mottling. I pre-dry religiously and know the difference anyway. Let's just say there are quite a few opinions about Kraft out there which are analogous to mine. It's not just about acid. Scrap museum board absorbs excess moisture far better anyway, provides a more realistic cushion when pressing, and is automatically re-dried each step, after initial drying at the start of the session. As far a Kraft being a dust seal at the rear of a framed assembly, in this day and age it must be assumed that intelligent technique means there something else providing a barrier between the Kraft paper and the picture mount itself, namely some kind of inert backing board or sheet of poly. I've sure seen a lot of otherwise valuable watercolor paintings from several decades back ruined by ignorance of this requirement. Same goes for the rabbets of wooden frames - they should be sealed with shellac (not varnish). But my
main argument against Kraft is that you don't really know under what conditions it is manufactured, and therefore what else might contaminate it besides general acidity. It is manufactured with these kind of applications being a priority. Or you might not have had a problem before, but then the mfg or distribution
source changes without you being aware of it. Someone like me, who deals with truckloads of such products, might understandably have a different perspective
than a frame shop, because shifts in the landscape are more painfully apparent, esp nowadays with rampant outsourcing.