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Ed K.
4-Jul-2006, 00:17
Hi -

I'm experimenting with some alternative emulsions. I'm looking for some suggestions for hardening additives that will help gelatin adhere to paper well, and hopefully not demolish the image too much over time. A vast body of research has been done on this ( see US Patent 4612280 at the gov patent search site for a good list and discussion of it), however I'm not looking to produce a new commercial product or buy complicated machines and a team of scientists to do it like Fuji did ). Actually, reading the patent was interesting for its discussion of issues - those guys really know their stuff!

Surely, there are some tried and true gelatin hardeners that work pretty well for manual coating, no? Please post suggestions if you have some. Chrome Allum? Others? I do expose with UV, so possibly UV activated solutions could be interesting too. Also, I have some LPE512 that I will try tomorrow as a direct addition to the emulsion instead of in the first clearning bath ( tried that tonight, it helped a lot, but didn't quite work in the end ).

I make an abosolutely rich and lovely brown print with a perfect color tonight on heavily gelatin sized paper, however it washed off the paper ( don't laugh at me to hard ) - I think I'll have something terrific if I get a nice hardener that still allows iron to be removed in a wash. The look of the print was really special, so I'd like to get this nailed.

Also, if anyone has sized paper with Agar Agar or other gelatin substances with good results, I'm curious to hear about that.

Thanks in advance for suggestions!

Donald Qualls
4-Jul-2006, 08:41
Do you mean the sizing gelatin washed off, or did you coat a second layer of sensitized gelatin over the sizing? One thing that can help is to use a harder gelatin to begin with -- a higher bloom number. Knox gelatin is said to be on the soft side for this application, though it has the advantage of being easy to get. Beyond that, there are some tricks I've seen mentioned in connection with salted paper printing (which is the underlying chemistry for albumen as well, and is often used with gelatin sizing and even applied in gelatin solution prior to sensitizing with silver nitrate); it might be worth looking up the information on salt printing with a gelatin salt solution applied to gelatin sized paper.

You might also ask over at APUG; PhotoEngineer there is Rowland Mowry, a former emulsion development engineer for Kodak, and he's recently started giving workshops on making hand coated emulsions suitable for paper, film, or even glass plates (including reinventing coating blades that are affordable for ordinary photographers, capable of putting a commercial quality coating on an 8x10 area of a 10x12 sheet). I'm certain he has the information you need, though I'd be pretty surprised if it didn't come to "use a photo grade gelatin of X bloom and it's not a problem."

Ed K.
4-Jul-2006, 15:03
Hello Donald!

Thanks for suggestions - here's a tad more info -

While waiting for a different batch of photo gelatin to arrive, I tried using a very pure gelatin from Maco - LPE410. The bloom number is not listed, however it is specified as an extremely pure photo gelatin. Previous experiments with Knox proved undesireable, mostly due to contaminants or some additives in it perhaps. I was unable to find a bloom specification for the Maco product.

While soon I shall try emulsions that incorporate gelatin, I used a mixture to precoat the paper, however I did use 20% more gelatin than recommended. After an initial drying period, sesitizer was absorbed into the gelatin at about 3x the normal amount needed to single-coat paper, however the paper itself got very little gelatin. In other words, the image barely sunk into the paper, and a generous amount of sensitizer remained in the gelatin layer. On exposure, flattening pressure between the neg and the dry gelatin resulted in a smooth, slightly glossy surface with very rich tones and great range. When I cleared in water mixed with a hardener from Maco, followed by water, the image was utterly fantastic looking. Fixed it, and it looked even better. I couldn't believe my eyes. Alas, after soaking in the wash tank for about 12 minutes, the emulsion disolved and only the small part that got way down inside the paper remained, the image washed off.

Previous experiements with starches were inconsistent and generally grainy looking, plus there were issues with contamination. The gelatin experiements are producing the best colors and finest grain / most vigorous looking image. Having a gelatin layer on the paper makes the coating rod work like smooth magic; a nice feel and good coat.

I have heard of adding hardener to fixer instead or in addition, which might work, however I need more adheasion and hardening at the first step. Today, I'll try the Maco hardener in the coating steps or in the pre-coat steps, and in a week or so, I'll just try some early formulae for emulsions that contain gelatin; they sound promising.

It is also possible that a very small amount of starch, such as rice starch, might be a good addition to hardeners because starches do adhere to things. If the hardener I have works, I'll be looking for a less toxic formula that still gets the job done.

Thanks DQ!

BrianShaw
4-Jul-2006, 15:32
Formaldehyde?? A long, long time ago I used to use this to cure (harden) gelatin sizing on paper.

Ed K.
4-Jul-2006, 16:05
Aldehydes are certainly a possibility, however I hope for something a tad less dangerous in terms of vapors... the Maco hardener is not formadehyde, however it is an aldehyde type mix up. How did the formaldehyde work for you? Did it prevent "wash off" ?

Don Bryant
4-Jul-2006, 18:34
Aldehydes are certainly a possibility, however I hope for something a tad less dangerous in terms of vapors... the Maco hardener is not formadehyde, however it is an aldehyde type mix up. How did the formaldehyde work for you? Did it prevent "wash off" ?

Ryuji Suszuki <sp?> has recommended gluteralhyde <sp?> as a hardner. Also some have recommended glyoxal. I have used glut for hardening gelatin for gum printing. Formalyn, glut, and glyoxal are have potential helath risks involved so beware of those issues before using any of them.

I beleive the Maco hardner contains glut.

Don Bryant

BrianShaw
4-Jul-2006, 20:57
Aldehydes are certainly a possibility, however I hope for something a tad less dangerous in terms of vapors... the Maco hardener is not formadehyde, however it is an aldehyde type mix up. How did the formaldehyde work for you? Did it prevent "wash off" ?

It worked pretty good. The sizing actually stuck to the paper -- no wash-off. I, too, desired something less dangerous. Formaldehyde is pretty nasty stuff. Buying it was an interesting experience. The chemical supply company insisted on asking lots of questions to assure that I was knew what I was doing and then giving me a long safety briefing.

sanking
5-Jul-2006, 10:22
You might also ask over at APUG; PhotoEngineer there is Rowland Mowry, a former emulsion development engineer for Kodak, and he's recently started giving workshops on making hand coated emulsions suitable for paper, film, or even glass plates (including reinventing coating blades that are affordable for ordinary photographers, capable of putting a commercial quality coating on an 8x10 area of a 10x12 sheet). I'm certain he has the information you need, though I'd be pretty surprised if it didn't come to "use a photo grade gelatin of X bloom and it's not a problem."

I second the suggestion about getting in touch with Ron Mowery on APUG. I sent a few days with Ron at the Formulary this month and we talked about emulsion hardeners all morning. He worked with this stuff for a living for several decades and really knows his stuff, not just the theory but the real down and dirty of practical use.

Sandy

Ed K.
5-Jul-2006, 15:57
Thanks Brian & Sandy - since you know him, would you mind inviting him to post here? Otherwise, no problem, I'll get in touch with him. And thanks again Donald.

Update on the experiments -

Finding that argyrotype and "van dyke" brown print are similar, with the argyrotype being more picky about contaminants, I did last lights experiments with argyrotype juice, the Dr. Ware formula. It lets one easily see how much iron is being removed at first, so it's a partial indicator.

The Maco hardener addittive did produce substantial hardening after curing for 24 hours, however the gelatin was still soft enough to swell during processing. No wash off, rich deep brown color, even better more rich dark brown color when gold toned prior to fix, and only a bit of "dry down" effect - mostly in the shadows. I ferrotyped one for fun, and it dried to a hard gloss, the air dry one had just barely a bit of gloss, really 80% matte, with paper texture showing up fine. Deep, satisfying tones, great shadow detail and nice clean highlights. The gelatin road seems worth looking into a lot more at this point. The color and richness of the image was wonderful. Speed of Argyrotype juice in gelatin is about the same as POP, however the Argyrotype in gelatin has more contrast in the shadows by far and a deeper tone before and after a short toning. The matte with just a hint of gloss on the texture is very pleasing to me, as is the ability to tone or leave as-is for an interesting image color.

In addition to the gelatin issues and perfection of that aspect, the spector of proper removal of unused metals seems challenging. Gelatin does seem to slow the release of residual iron, although visually it comes out. I'll try salt and/or citric acid for iron removal. If anyone has suggestions as to how to test for good removal, speak up.

Donald Qualls
5-Jul-2006, 19:52
Aldehyde hardeners are potentially bad news -- glutaraldehyde in emulsions have been implicated as being at the root of a number of folks who got extremely ill from being in the room with X-ray film processing, and formalin is at least as bad (and more volatile). Chrome alum (in acid fixer) is the old school method, and is probably what's in the Maco hardener.

Potassium dichromate will harden gelatin when exposed to UV light, but that's an entirely different alt process... ;)

The big key for removing residual iron salt is to acidify the water a little; if the water is alkaline (as tap water is in many regions in the summer and some year-round) the iron will form the insoluble hydroxide and you'll never get rid of it. Recommendations I've seen in connection with VDB are to do the first wash with either acetic or citric acid about 1/4 the strength of stop bath. If you add a little salt to this bath, you'll also convert any unreacted silver nitrate to the chloride, so it fixes away cleanly and doesn't hang around in a sensitive form to darken your print in the wash.

Say -- acetic acid, and salt -- that sounds like pickle juice!

Ed K.
5-Jul-2006, 20:39
Aye Donald - good thoughts.

The Maco stuff it turns out has Acetic acid, Glutaraldehyde and Sodium disulphite. I mixed the hardener and gelatin outside and made the gel coat outside too because this time I wasn't adding light sensitive ingredients to the coat. No problem for that, however who knows what the exposure was while wet. I'll take that part under advisement. This stuff is not worth getting sick over, at least to me. The Maco stuff is concentrated, not terribly expensive, and 20ml per 500ml of gelatin seems to work pretty well - the stuff remains flexible after drying. A harder gelatin in the first place would be very desireable - the Maco stuff is intended to be a gloss coating for already coated base papers and a part of their Liquid Emulsion Black Magic set, which I don't use.

Salt doesn't seem to help - sure, any excess silver will come out, however it creates problems with the iron on contact in a first experiment. Acetic acid was also tried. It doesn't seem to work very well - perhaps a much, much longer soak is needed than 8 minutes. Acetic acid did seem to alter the color a bit - more toward a buff color ( tried it because I was out of citric acid ) The gelatin, while soft, seems to help keep some of the iron in the print, and it is visible too. I suspect that a van dyke formula that is intended for gelatin incorporated into it will produce better results - I'll get the rest of the ingredients and try it.

I noticed that Photog's Formulary had baryta paper ready for coating. Intrigued by the possibilities of that, I ordered some to see what happens - perhaps that is a practical answer. I do really like the texture and feel / heft of 300lb Artistico paper for this, and how it looks with a gelatin layer on top.

What a shame, I dropped a jar of pickles accidentally last night while bringing home the 4th celebration hot dogs and such from the store. Had I known better, I would have brought a test print home to mash on the garage floor in the puddle. Ever try polsihing the paper surface with a pickle? ( okay, you albumen printers - that's a yoke man ).

Today's test print, with no citric acid yet, and perhaps too much gelatin and too much hardener, has some light orange stains here and there ( not too bad though ), and a marvelous color and sharpness. With luck, less gelatin in the mix, and citric, it could work. For tonights coat, I'll try adjusting the mix and also try a mix of gelatin and sensitizer.

Too bad nobody can just manufacture a few of the papers, or at least a run or two of papers ready for nitrate. Sure, it can be fun to "craft" this stuff, however I get the feeling that it has been done so much better in a plant somewhere, many years ago. There is a good part to it though, and that is once some recipes are hammered out, at least there is no worry of the coating company going out of biz.

The UV idea indeed is in reponse to other processes, however the initial intention difers. I thought perhaps a coating of gelatin as a sublayer, then expose the whole survace to UV, might serve to make a harder layer and cure it better in less time. As I haven't tried any of that, I don't know how that might work, thus the question.

So, Glyoxal, Chrome alum, or a free form of Formadehyde. I'll read up on which is the least evil. Let's see, while Potassium Dichromate is part of migrain remedies, it is a known carcinogen, and harmful to the environment. The others don't sound much better. I might have to shelve this idea for the health and environmental factors, or come up with a different binder.

Let's see....inert, flexible, non-reactive, non-hazardous, porous enough to allow water in and out, good adheasion, and clear. Almost sounds like PVA, except that PVA re-disolves in water. I wonder if Liquitex would make a sublayer suitable?

Since you've got your chemist hat on, isn't the thing desired more at a "cross linking" agent than specifically a hardener? Perhaps there is a chemical that doesn't harden the gelatin much, yet does increase adheasion a bit, or raise the melting point another 20-30 degrees?

And as you allude to Donald. there can be issues with lingering chems causing problems down the line.

Donald Qualls
6-Jul-2006, 12:16
Let's see....inert, flexible, non-reactive, non-hazardous, porous enough to allow water in and out, good adheasion, and clear. Almost sounds like PVA, except that PVA re-disolves in water. I wonder if Liquitex would make a sublayer suitable?

Since you've got your chemist hat on, isn't the thing desired more at a "cross linking" agent than specifically a hardener? Perhaps there is a chemical that doesn't harden the gelatin much, yet does increase adheasion a bit, or raise the melting point another 20-30 degrees?

And as you allude to Donald. there can be issues with lingering chems causing problems down the line.

Cross-linking is exactly what dichromate does when exposed to light, and it does it with any colloid -- gelatin, casein, gum (which is a form of starch, dunno if it'll do it with unconverted starches), even collagen (chrome-tanned leather makes use of this, using a different form of hexavalent chromium). I'd expect it would do the same for PVA. As you note, though, it's a powerful irritant, can cause skin blistering, has considerable acute toxicity, and is a suspected carcinogen; in the environment, despite a lot of governmental concern in some areas, it oxidizes to the far less problematic trivalent form very rapidly (signaled by a color change from red/orange to greenish -- which, BTW, can be done in a photographic setting by adding sodium sulfite). There are other cross-linking agents -- cobalt drier, for oil paints, greatly accelerates the normal oxidation-based cross-linking that cures linseed and other vegetable oils. Similar drying agents and curatives are used in enamel paints and the so-called "epoxy" paints, but most of those are even nastier than aldehydes (epoxy paints at least used to be toxic enough it could be lethal to spray them without either a 4-point updraft booth or a full isolation suit). Isocyanates that cure urethanes and similar thermosets are very similar to the stuff that killed all those people in Bhopal back in the 80s. Bottom line, anything that will crosslink gelatin can crosslink the proteins in your corneas and mucous membranes -- potentially blinding and suffocating you -- and even if they don't go that far, will lead to damage that can progress to cancer over time.

You need any alternate carrier to be water permeable (for washing), so you can't go too far down the line away from water softening; additionally, it has to be permeable for the ions that form the iron salts, for thiosulfate and its complexes with silver for fixing, and for the residual stuff that comes out in the final wash (still more thiosulfate complexes, mostly). Given you don't want selective hardening (as would be used in gum bichromate, casein, carbon/carbro, gumoil and bromoil), you need a general hardening/crosslinking agent that isn't too toxic and doesn't depend on light exposure. Alum is probably still the best alternative to glutaraldehyde (Anchell and Troop don't like it, but seemingly mostly because it requires an acid solution and they just recommended using only alkaline fixer on the previous page), though adequate ventilation can prevent aldehydes from ever being a problem (the problems that have arisen with X-ray processing were in poorly ventilated X-ray labs, processors running above 100F to give extremely rapid processing, and emulsions that had to be hard enough to avoid damage at such extreme temperatures).

You might try plain alum like what you'd get from a pharmacy as an oral antiseptic (potassium alum), in a solution of 15 g/L with 5% acetic acid, either 7.5 g/L boric acid or 15 g/L sodium metaborate, and 15 g/L sodium sulfite -- this is the same as Kodak F-5 or F-6, respectively, without the hypo. This could be applied and washed out before sensitizing, in your application; alternately, you could simply add a small amount (a few g/L) of potassium alum directly to the gelatin in the form of a stock solution replacing some of the water; that would harden the gelatin before it's applied, though it might be tricky to control (you still need it to soften enough to spread without requiring too much heating).

Oh, for washing out iron, you might try acidifying the water with a tiny quantity of sulfuric acid, if you have it on hand (you can buy battery acid for about $4/quart at auto parts stores, it's a 30-35% solution), or you could use sodium bisulfate to provide and acidic sulfate solution without the need to keep sulfuric acid around. Ferrous sulfate is soluble enough in acidic solutions that it was once used as a developer (dissolved in ethanol and acetic acid) for wet plates...

Ed K.
7-Jul-2006, 20:35
Good thoughts again Donald. I'm going to try some artist grounds as a sublayer, then see what can happen from there on up. I did find an absorbant ground that seems like it might just do the trick....we'll see!

Ed K.
12-Jul-2006, 01:53
Update - after some more tests

Baryta paper from Formulary makes a good base for gelatin on top, however adheasion is an issue for anything but gelatin. Also, Artcraft's 250 bloom gelatin turns out to need little hardener compared to the Maco stuff, and it does stick well to the baryta paper. Dramatic difference in mid-tones ( smoother ), and very interesting to experiment with. I tried adding a bit of rice starch, which definitely increased tack a bunch - perhaps with the right starch content, temps, and tween, it will work out without even resorting to hardeners much.

Donald Qualls
12-Jul-2006, 07:54
Cool! Keep good notes -- and maybe put up a web page with the process and results?

I do wonder if there might not be a market for a baryta paper coated with salted gelatin. The paper in this form would keep for decades, then a quick wash with silver nitrate solution and let dry, and it's ready to expose. Don't know if you'd be able to keep it flat while it dries from sensitizing, though...

Ed K.
16-Jul-2006, 17:30
All sorts of work to this end is on the 'net. So many variations, so many varied results!

Experiments with gelatin and denatured alcohol did not work out. Thought that would speed drying by replacing half the water with alcohol. No luck, and no good adhesion either.

Here's one try -

Super clean glass. 2 rounded tsp. 250 bloom gelatin to 300ml water, warmed to just past full melt of gelatin, around 110F after 20minute bloom. Add 1/3 tsp. photoflow, stir, increase heat 10 degrees, heat for 5 more minutes until most bubbles gone from top. Decant into photo-only use clean cup, add 7ml Glyoxal, stir gently until mixed. Strain through paper towel into another clean cup. Onto level glass, with three layers of masking tape creating border around edges, and dam to hold layer of liquid gelatin, pour. Lift edges slightly to help spreading, let settle.

After 18 hours dry time, a perfectly smooth, clean gel coat that is flexible. Holds pretty darned good to glass but can be pealed at an edge like a decal. Interesting, I think I just made a very good start for a home-made printing carbon tissue! Hmmm, leave that to experts...

Wishing I had incorporated salt already, and wishing I could have the Forumulary be open on Saturday..well, and have a transporter from Star Trek, I tried VDB mix. VDB does not like the gelatin - it grains ( Argyrotype LOVES gelatin and looks rich, but I didn't have any ). No matter, we're testing for "lift off" and disvolving of gelatin at room temp processing, so press on with just the base test.

Expose, clear in water. Hey - no liftoff, just milky excess silver salts, etc. Image rich. Interesting. Why keep up the good work? Add 2 tsp citric acid to 1 liter water for next bath, want to remove excess iron, right? Gently soak.

Uh oh. Shrinking a bit at edges, which are in from the edge of the glass due to masking. Some slight buckling showing on one edge, coating a tad thinner there. Okay, image is still on there, and three edges are great, no buckling in center either. Fix in weak hypo and gold toner mix leftover from some pop. Uh oh, not so good there, pretty quick bleaching out. Who cares, this is just testing the gelatin, will get the rest right when chems arrive.

Result? After gently washing, only one corner liftoff, definintely no dissolving to speak of, gelatin porus enough to support processing. This going better, and glass is a fun "acid" test of sorts. If it will work on glass, then just put the piece of wonderglass on paper in a frame, no?

Thoughts - very slightly too hard gelatin, it shrank on one edge a bit. Probably too much photoflo, although another guy's account said he uses triple that amount. Have heard about acrylated gelatin - I suspect it would be a good thing to try as a top layer. The edge that started having problems was the one I barely started peeling before cutting a score inside the masking tape with a razor blade. I won't do the peel test next time! Easy to observe compatibility of a sensitizer with gelatin formuale because there is no paper to prevent viewing.

I suspect that the photoflo ( isn't it mostly Propylene glycol?? ) serves a similar role to glycerin, in that it makes the emulsion more flexible. This could be desireable if one wishes to use some kind of transfer technique by peeling it off. Counterintuative that this also makes for better adhesion to a point. Also suspect that a tad more drying time, perhaps double, would be the right thing to do if less hardener.

At the thickness of the masking tape layers, drying was quite good in 18 hours. A thicker leftover in the bottom of the last cup I used was more like rubber with a "rubber balloon" skin on top. It peeled out easily from the cup with the aid of tepid water.

A very thin residue of unhardened gelatin that I poured over teflon and left to heat dry in the bottom of a pot on a cooling burner produced what might be the start of some creapy new candy - "Scar Tissue! - it's like eating King Kong's Dadruff Flakes - what fun kids!". Almost brittle, quite tough, with light texture and small bubbles. Not very elastic.

Next experiment - other hardeners, and definitely mixing salt into gelatin and then soaking final result in silver nitrate, or simply combine Argyrotype mix into a one-pour solution of gelatin. As the slightly thicker sides of gel on glass did better, plan to use one more tape layer all around. Clarity of gelatin was quite amazing and good though - smooth. Masking tape helped too; used a razor blade to cut it. Less photoflo! Betcha' anything that when the chrome alum comes in, more happiness will result, and at least recipes of others can be tested out.

When this work on glass, I may be rather pleased. It does seem that once a suitable personal gel skill set can be obtained, the applications including on paper, will be fine. I guess it's part of the process to go through experiments...

If I do find any magic gelatin bullets layin' around, I'll be sure to post an example of something that actually works. Stay tuned...

If you've got a suggestion - I'm all ears!

Patrik Roseen
17-Jul-2006, 05:53
Hi Ed, I really enjoy this thread and got interested in the issue.FWIW I read in an old photobook from the 50's how to harden gelatin by adding either chromealun, kalialun or formalin to the fixer. chromealun is said to be very efficient as it can raise the meltingpoint from normal 32 C to over 95 C. it reaches its optimum at PH 4.3 Trying to understand what the book says it mentions a solution of chromealun of 5% (?) Adding salt is also mentioned but only as a temporary hardener with the effect of not allowing the gelatin to soak up and get 'swollen'. Pls do not kill me if this is total nonsense...Patrik.

Ed K.
17-Jul-2006, 15:08
Patrik - thanks good thoughts too!

Indeed, raising the melting point is a big part of it - even hardened gelatin melts at some point, right?

What's interesting is the action of salt as a temporary hardener. My purpose with the salt was simply to make silver chloride / light sensitive silver compound, essentially a salt print for initial experiments until the gelatin part works out best.

Formalin/Formaldehyde was rejected due to the strong oder / carcinogen part, even though I do that part outdoors just in case. I want to have something with less vapor.

Most recipies do call for potassium or chrome alum - so this will be tried next. Artcraft doesn't sell pre-mixed collodion or chrome alum at this time, so next experiment may well be with potassium alum a slightly less dangerous alum than chrome, although possibly less effective. I seek a balance between safety and effectiveness, with a strong emphasis on safety.

Keep the suggestions coming!

Patrik Roseen
17-Jul-2006, 15:23
Ed, I guess you have looked everywhere through internet sources and maybe you did or did not come across this page. It talks about dryplate on glass but would be very similiar I guess to what you are doing on paper.

The author puts Photo-flo in the mix to make the emulsion spread easier on the glass, maybe it is worth trying to get the emulsion deeper into the paper (?)

Anyway, here is the page:
http://www.alternativephotography.com/process_dryplate.html

Patrik Roseen
17-Jul-2006, 15:44
Sorry forgot to mention...the author use chrome alum already in the subbing layer:
"A. Heat up 50ml. of distilled water to a maximum of 50&#204;C. (about 125&#204;F.) in a beaker. Then pour 1g. (1/4 teaspoon) of chrome alum into this water and stir with a standard darkroom paddle until dissolved. Without this hardening agent the subbing layer tends to frill and sometimes completely separate from the glass during tray development; so the small expense is worth it."
It's bought from Photograher's Formulary in the US...apparently...

Ed K.
17-Jul-2006, 15:47
Thanks again Patrik!

I'm trying to do glass first. Paper generally comes out pretty nice without too much headache if it's the right paper, humidity, etc. However, paper with a perfect gelatin coat is more interesting yet.

Yes, I've read most of the accounts on the net, which vary a lot, and I am trying to verify some of the accounts. I suspect that some accounts stop talking when they actually arrive at the best solutions, however I'm going through them.

One thing I had thought was that patents for such things would now be expired. Guess what? There are dozens and dozens of patents on all this that are only a few years old at most. I don't wish to get into violating patents, however the theory, methods, and principles of doing all kinds of gel coats are really well discussed in patent literature. I think I'll have a look at some of the expired patent information for enlightenment - to get a patent, one has to disclose the whole process, and in early patents, they actually had to prove that it worked more often than today's "patent the air we breath" approach to patent approval.

One failed image that washed of the glass in an early experiment was so lovely, I developed a wish to make that image stay. I figure eventually a print on ground glass, or specially backed thin glass would be marvelous, and once mastered, open the door to all kinds of gelatin, protein and polymer experiments. There is also a photo-ceramic process or two, and one that includes baking in to enamel - all interesting as well.

As a side note - failed experiments still give useful understanding of issues, or produce results applicable to other things. Here's one:

I tried precoating the glass with water-based polyurethane clear gloss varnish. It went on well enough. As a fun fling, I sprayed a SINGLE coat over a watercolor paper inkjet that looked somewhat too gray for public consumption. The stuff dried on the paper inkjet surface to form a wonderful soft, smooth, moisture resistant luster with a bit of paper grain to it. The luster was definitely gloss but not "hard candy". Clear enough too. While it might not be archival, it sure seemed like a way to get an aqueous coat on a print, and it made it rival a certain "fugative" - depth look of a real gelatin print. I may not use it, but other attempts to spray soft paper, or even coat in damar, etc., just soaked up vast quantities of coating - this did not. On glass however, the varnish peeled off like a decal - stretchy stuff. In water, it really came off glass at 80F. The gel stuck to it about as well as to glass using the same gel. Seems like a way to cast a thin protector layer for a gel transfer, however I would worry about the archival nature of it with the solvents in the urethane. All interesting though!

Aha - on the suggestion of Mike at Artcraft, I see that wetplate.com has a forum with resources, including possibly a way to purchase premixed collodion ( don't know yet ). I'm going to check that out too -

http://www.collodion.com/forum/default.asp

Okay, Formulary has chrome alum and premixed collodion, both useful, both needing extreme care... There is a workshop coming up this month that they are selling - I wish I could attend it, however anyone interested might check their site for the wet plate collodion workshop.


Keep the suggestions rolling in!

Ed K.
26-Jul-2006, 22:17
Update - July 26, 2006

Chrome Alum is the stuff to use. It is far more effective than glyoxal. I did an experiment with both. The glyoxal gelatin dried with a yellow color, and took a very long time to harden. Chrome alum definitely works nicely, and not much is needed.

More chrome alum results in a less glossy surface, less gives more gloss but softer of course. Wash-off doesn't seem to be a problem now. The issue now is to gradually lower the amount of chrome alum until the processing goes well.

Michael Daily
27-Jul-2006, 15:50
Hi, Ed,
From research on developers and increasing print density through altering the stop and fix baths, I remember something about Photoflo causing problems with developers. We used Zephiran HCl (benzalkonium chloride--antiseptic) as a non-ionic surfactant to help dispersing and penetrating the gelatin on paper. As this is non-ionic, it seems to not react with the other reagents and keeps mold from forming. The coatings were done with a wire-wrapped glass rod to meter the thickness--the way test coatings were done by the "big boys" at the photo test labs. The gaps formed by the adjacent wraps of wire allowed just the right amount of coating to be left behind and self-level before drying. Let me know if this is of interest and email me if I can help further..
Michael

Ed K.
27-Jul-2006, 16:53
Hi Michael,

Thanks for the additional information - indeed, I may email you with some more specific questions once I complete the sub layer and main gelatin layer experiments.

A couple more notes - potassium alum, while it doesn't seem to be as powerful in hardening as chrome alum, has two very nice properties - a.) It is white, not gritty brown, it desolves easily b.) adding it slowly to gelatin noticeably increases viscosity and tack immediately, plus raises melting point - all very good qualities. Chrome alum does work, but the results seem more indirect. The stickyness in particular is good. Alcohol appears to dissolve and thin the mixture somewhat, and it does seem to kill tiny bubbles a bit. For some reason, salt also tends to make the whole mess more sticky, and influence the melting point a bit. Ideally, a good coating would have high tack, elevated melting point above normal gelatin, clarity, ease of coating and fast drying. So far, although I really liked the improvement of chrome alum, I'm like potassium alum even more in spite of having to use more of it.

I did find a site by Saul Bolanos for his Lucenta liquid silver chloride emulsion along the way - he outlines many techniques that cover most or all of what I'm up to here, except that I wish to use various sensitizer recipies. His notes are quite detailed, complete and fun plus they reflect many years of study on the subject. Well worth a read and probably worth getting some of his nifty emulsion too!

Here, I'm verifing methods that are documented, in many places, to understand better what variables make them work, where there is room for changes in procedure, and the most efficient methods given my workspace.

Ed K.
3-Aug-2006, 18:56
Duh!

I have heard mention around here of coating blades, however no mention of coating rods. There are several manufacturers of rods and machines that allow precise coating amounts to be deposited. This opens up a whole range of ideas for making better coatings on paper as well as glass, etc. Coating thickness does matter as well.

In addition, a surprisingly good coating method that could possibly be used for photographic plates and prints on glass would be based on the one mentioned by some holographers:

http://www.xmission.com/~ralcon/dcgprocess/p1.html

The above is very interesting, because a few thin coats could be made in fairly low time on glass for plates or prints. The first coat could be more for adhesion, followed by a build-up of other coats. It's true, they are using a different photosensitive process - hardening of gell, however the coating and annealing notes are quite interesting.

Patrik Roseen
4-Aug-2006, 04:55
Update - July 26, 2006

Chrome Alum is the stuff to use. It is far more effective than glyoxal. I did an experiment with both. The glyoxal gelatin dried with a yellow color, and took a very long time to harden. Chrome alum definitely works nicely, and not much is needed.

More chrome alum results in a less glossy surface, less gives more gloss but softer of course. Wash-off doesn't seem to be a problem now. The issue now is to gradually lower the amount of chrome alum until the processing goes well.

Hi Ed, I'm glad to hear the Chrome alum actually worked for you! I will follow your success with interest. /Patrik