My contact frame needs new glass.

[Stephanie Brim]

I went into an antiques store in Ames this weekend on a whim to see what they had. I mentioned the Seroco I didn't buy, but neglected to mention the contact frame that I *did* buy. It was a self-masking frame by Kodak made in 1915 or so...but it was for smaller format. So I modified it and, presto, I now have a frame perfectly sized for contact printing 5x7 on 5x7 paper. It pained me to do it somewhat as everything but the glass is in pristine condition, but I bought it to use, not display.

The glass would've been in pristine condition as well if it hadn't been for my rough handling...I kinda broke it when I tried a little too roughly to get it out of the frame before I had completely removed the metal masking blades.

Can someone recommend where the heck to look to get another sheet of glass?

[Sal Santamaura]

...The glass would've been in pristine condition as well if it hadn't been for my rough handling...I kinda broke it when I tried a little too roughly to get it out of the frame before I had completely removed the metal masking blades.

Can someone recommend where the heck to look to get another sheet of glass?Consider this to be good fortune.

Go to a framing shop. Ask them to cut you an appropriately sized sheet of the finest-textured "non-glare" glass they have. Single-side texture is fine. Make sure they cut a piece that has no imperfections, e.g. bubbles, surface scratches/chips, etc.

Install it in your frame with the textured side facing the negative. You'll never experience or have to ask how to overcome Newton's rings. :)

Enjoy!

[Daniel Unkefer]

Or a Hardware store that can cut window glass for replacement in windowframes.

[Stephanie Brim]

Tomorrow I'm going to call the people at the local glass shop and have them cut me 4 pieces of non-glare glass. At $3 a piece, I figure that it may be a good idea to have spares. :D

[Shawn Dougherty]

Consider this to be good fortune.

Go to a framing shop. Ask them to cut you an appropriately sized sheet of the finest-textured "non-glare" glass they have. Single-side texture is fine. Make sure they cut a piece that has no imperfections, e.g. bubbles, surface scratches/chips, etc.

Install it in your frame with the textured side facing the negative. You'll never experience or have to ask how to overcome Newton's rings. :)

Enjoy!

This is excellent advise.

[Michael Cienfuegos]

I too have one of those old Kodak self-masking print frames. They are great! I was able to get a nice replacement piece of glass from a glass shop where I have done business before. I didn't get the Anti-Newton glass, but it seems to be doing ok. I use it mainly for cyanotypes.

Good luck in your hunt.

m

[IanMazursky]

I was wondering if anyone has ever used anti glare glass (slightly frosted) for contact printing.
I have a lot of it from my grandfathers studio and i was wondering if its worth using it for Lodima?
Thanks

[HBDesert]

You should also make sure that it is not "UV" glass. That is to say a glass with some kind of UV coating.

Take Care,

Doug

[David Karp]

I got a piece of replacement glass for my contact frame from Steve Hopf when I ordered a GG from him. It was perfect, with no flaws.

[Michael Jones]

I've used "anti Newton" glass from Focal Point for more years than I am willing to admit. Never a problem.

http://www.fpointinc.com/glass.htm

Mike

[Drew Wiley]

Ditto to above. Focal Point can supply glass in different thicknesses and custom cut
to size. Who wants Newton rings? Don't use conventional nonglare picture glass, which
is likely to be thin and fragile, might not give ideal contact, and has a bit of diffusion
effect.

[Sal Santamaura]

...Don't use conventional nonglare picture glass, which is likely to be thin and fragile, might not give ideal contact, and has a bit of diffusion effect.Stephanie was looking for glass to put in a 5x7 frame; I can't imagine any non-glare framing glass that wouldn't be robust enough for that application. I've had no flex/contact issues with it up to 8x10. For my 12x15 frame, I ordered a sheet of Tru Vue Reflection Control. It's 2.5mm thick, thicker than most, and maintains perfect contact even with 11x14 prints.

What possible difference could glass diffusion make in contact printing? If the negative and paper are in intimate contact, illuminant collimation (or lack of same) has no effect. In fact, my light source for Azo printing is a 40W bulb in a 10" Smith Victor reflector with the diffusion attachment clipped on! Sharpest prints imaginable, even when I get nose grease on them viewing up close with my -6 diopter eyeglasses removed. :)

[Drew Wiley]

Good question, Sal. Perhaps most printing papers will not show much difference, but with films the sharpness and edge quality can differ a bit. And there are times when one might use the contact frame for film to film. I do it quite a bit, though most of my frames are pin registered. I have tested a lot of types of glass too. With alternative processes you also have to be aware of the UV characteristics of the glass. Some of the coated picture glasses block UV a little, which would obviously be unwanted in certain cases. With larger frames strength of glass becomes an increasingly important issue. Just some parameters to keep in mind. I'm not suggesting they need apply to every instance.

[Stephanie Brim]

The glass is exactly the same width as the glass that was in the frame to start with, so there shouldn't be a problem.

Another issue I have is whether or not to replace the felt. I think I'll see how it goes first.

[Sal Santamaura]

...with films the sharpness and edge quality can differ a bit. And there are times when one might use the contact frame for film to film...I'm still not clear why, if the two pieces of film are held in intimate contact (emulsion-to-emulsion), illuminant collimation would have an observable impact on sharpness. Are you subsequently enlarging the film duplicate? If so, by what magnification?


...With alternative processes you also have to be aware of the UV characteristics of the glass. Some of the coated picture glasses block UV a little, which would obviously be unwanted in certain cases...There are two types of picture frame glass coatings. The first, anti-reflection (AR) coating, is similar to what's applied to lenses. It has minimal effect on UV transmission, but I've not found such glass to work particularly well in suppressing Newton's rings. The second coating type is applied to "conservation" glass. That's actually a plastic laminate which blocks UV. It is available on plain, "non glare" and AR glass as well as -- recently -- acrylic sheets. The laminate would definitely present a problem for UV-exposed processes.

I'd never suggest one of the "conservation" glasses for contact printing frames. Readers should be aware that any float glass will block at least half of UV. It's just that "museum" glass' laminate attenuates most of the remaining half, making for looooooong exposures with UV processes. A finely-textured, uncoated picture frame glass, appropriately thick for the frame size, will work perfectly in almost all other paper printing applications.

[Drew Wiley]

Just getting back to this thread, Sal. I'm aware of four different processes for optically coating picture glass, although I doubt if all four are still on the market.
They differ quite a bit. Plus there's a sandwich process, plus a strange type of plastic
film once used by Zeiss (but not for pictures per se), plus your various acid-etched
or blasted cheaper float glasses. Then you have a range of AN glasses specifically
meant for optical use, some still in production, some not. This list is of course overkill for the average person making a visible light contact print. Gets more selective for UV, and then even more selective if one indeed starts enlarging from
something made by contact (which I routinely do). It is also climate-related. Here
on the central Calif coast I don't get decent newton-ring supression with anything
but dedicated AN glass. It's just too foggy most of the year. I have experimented
with at least twenty different types of glass, so am not guessing at this. And some
of the films like 100TMax can be rather slippery and prone to rings.

[Ron McElroy]

......

What possible difference could glass diffusion make in contact printing? If the negative and paper are in intimate contact, illuminant collimation (or lack of same) has no effect. In fact, my light source for Azo printing is a 40W bulb in a 10" Smith Victor reflector with the diffusion attachment clipped on! Sharpest prints imaginable, even when I get nose grease on them viewing up close with my -6 diopter eyeglasses removed. :)

While I can't comment directly on the use of none glare glass in a contact frame, in the olden days of table stripping in the printing industry we would change the size of the image by simply placing a frosted piece of acetate on top of the negative we were wanting to "spread". Spreading would require a longer exposure than a normal dot for dot. All of this would take place inside a vacuum frame under a point source light.

[Sal Santamaura]

...in the olden days of table stripping in the printing industry we would change the size of the image by simply placing a frosted piece of acetate on top of the negative we were wanting to "spread"...What does "on top of" mean? Between the negative and the vacuum frame or between the negative and the halftone screen?

[Ron McElroy]

The sandwich inside the frame consisted from the bottom up:
1. The raw unexposed film emulsion up
2. The negative being contact printed
3. The frosted sheet
4. The glass of the vacuum frame.

The are lots of stacking combos the would yield different amounts of spreading
For the largest single step spreading the combo would be:
1. The raw unexposed film emulsion down, yes exposing through the back
2. Two sheets of clear .005 acetate
3. The negative being contact printed emulsion up
4. The glass of the vacuum frame
5. The frosted sheet on top of the glass outside of the frame.

These techniques were used primarily for creating mechanical trap (overlapping of ink) for the press. They also were used when dry dot etching scans to color correct the image.

[Tim k]

I kinda broke it.......



Thats the funniest thing I heard all day. I love it. I almost wet myself.

Thanks for the laugh. :D

[Drew Wiley]

Sal - the kind of effect which Ron referred to is analogous to unsharp masking, in which relatively subtle difference in diffusion material or thickness, or any added
diffusion characteristics of glass itself can accumulate noticably. One can easily overmask in the sense of too much edge effect or an actual dimensional accentuation. The younger crowd might think that unsharp masking is a term invented by Photoshop, but it's been around for a long time. Some of the old graphic
arts manuals go into the details. Sometimes even switching the brand of diffusion
sheet, or from mylar to acetate, will make a significant difference. I buy the sheet
materials in quantity, look for blemishes on a lightbox, then grade and sort out the
working sizes. In color printing these tricks are really useful to know, but sometimes
also in black and white work.

[eli]

I have both a 4x5 carrier, which needs glass and a scanner which I am salvaging parts from. Would the glass from the scanner be a suitable replacement for the original Omega glass?

Eli

[mcfactor]

On a somewhat related note, has anyone used the Print File Custom Negative Proofer? http://www.bhphotovideo.com/c/product/43109-REG/Print_File_PFCP_Custom_Proofer.html
I realize it doesnt have AN glass, but I havent really had problems with newton rings yet. It seems like a very easy (and inexpensive) option.

[Tim k]

Thats the funniest thing I heard all day. I love it. I almost wet myself.

Thanks for the laugh. :D

After thinking about my post for a while, I felt compelled to say that I thought that it was funny that you "kinda" broke it, not that you broke it.