Scanner glass for contact printing frame?

Does anyone here have experience or knowledge as to using flatbed scanner glass plates for making frames?

Though this is thin glass, I suggest it is strong enough to make a solid paper/ negative printer and the glass itself Optically clean enough to work well.

What do you think of using this material?

There's no advantage to it over plain float glass or the glass from a decommissioned picture frame. Besides, I expect that most/all scanner glass generally has some kind of plastic frame around it that needs to be removed, and the glass may damage or break in the process.

As you said, it's generally fairly thin, although this is not necessarily a problem depending on the construction of the contact frame and esp. how much pressure it exerts on the glass, and how the pressure is distributed.

Overall, not a very likely/sensible direction to look in. Why? Do you have a broken scanner taking up space?

eli griggs said:

Though this is thin glass, I suggest it is strong enough to make a solid paper/ negative printer and the glass itself Optically clean enough to work well.

What do you think of using this material?

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You really don't need anything more fancy than a $5 picture frame from amazon.

But scanner glass would work okay if you want to go to all the work to salvage it.

With many people replacing computer equipment every 18 months. or so, savaging scanner glass should be a simple matter of recycling materials that otherwise may go into the trash bin.

The most difficult work is removing the glue that hold the glass to the scanner frame and, if you're lucky, finding a large format scanner to work with, where the marking of the glue line is covered up by the wood frame of contact printer.

IMO

I bought an expensive piece of glass for the frame I made and it broke on the way home. So I went to the plastic supply store and asked for a piece of plastic that was not UV-blocking. After explaining the printing out process to the clerk, I got a piece for less than $10. I've been using it for several years and it works just fine.

I use the glass from two thrift store picture frames and some paper towels as a press to flatten finished prints. Those were about $3 each and would work fine for a printing frame.

Some of the processes and papers used by some of the practitioners call for a fair bit of pressure, applied very evenly.
The few printing frames I've encountered seem to vary a bit in how well they accomplish that.
All of them do seem, however to be easy to pinch your fingers with though, if you aren't careful .

Ideally, you want Anti-Newton-ring glass in a contact printing frame. That is often sought for flatbed scanners too. It's getting harder to find. My last set came from a company called Scan Tech in LA, who would cut it to any size you needed. But they went out of business during the pandemic.

Many sheet films are quite slick even on both sides nowadays, and quite prone to rings in my climate at least. Gone are the days when they had retouching "tooth" on the backside (maybe TXP still does). Then AN sprays arrived, but later got pulled due to nasty vapors. Graphics AN powder is just finely sifted corn starch - the last thing I'd want in a darkroom - it attracts booklice. You can also use an intermediate sheet of frosted mylar between the glass and your negative.

Acrylic plastic is not dimensionally stable and will bow, so it's not ideal for a contact frame unless it's a rather small one. If so, you can get a version of Acrylite FF which is subtly textured one one side for nonglare purposes, which will suppress rings. Ordinary cheap "non-glare" picture frame glass is so heavily etched that the pattern might show through on your print itself; and it's also fragile; but one can experiment.

I’ve salvaged scanner glass for a couple contact frames. One piece turned out to be tempered, and shattered into a thousand pieces when I tried to cut it. I used De-Solv-It to remove the adhesive residue. Basically it was quite a bit of work for a piece of glass. For my 8x10 frame I ended up ordering a piece of anti newton glass from KHB Photografix because I was having problems with newton rings with the scanner glass.

eli griggs said:

With many people replacing computer equipment every 18 months. or so, savaging scanner glass should be a simple matter of recycling materials that otherwise may go into the trash bin.

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Flatbed scanners for most of the consumer market went out of fashion years ago. What remains are scanners used by film enthusiasts like the people on this forum. You generally have to pry those scanners from the cold, dead fingers of their owners before they'll let go.

I respect your opinion but my hands-on experience is that plain float glass (salvaged from a cheap picture frame, bought from a glazier etc.) works just fine.

I also find it objectionable to scavenge the glass from a potentially perfectly functional scanner. Ridiculous. We shouldn't want this kind of thing in society, let alone encourage it.

koraks said:

Flatbed scanners for most of the consumer market went out of fashion years ago. What remains are scanners used by film enthusiasts like the people on this forum. You generally have to pry those scanners from the cold, dead fingers of their owners before they'll let go.

I respect your opinion but my hands-on experience is that plain float glass (salvaged from a cheap picture frame, bought from a glazier etc.) works just fine.

I also find it objectionable to scavenge the glass from a potentially perfectly functional scanner. Ridiculous. We shouldn't want this kind of thing in society, let alone encourage it.

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I suggest old scanners headed for the bin be the source for glass, not functional kit.

Even functional drum scanners end up in the dump if nobody is willing to take them for outright free. Gosh knows how many flatbed scanners end up in giant e-waste recycle bins, tossed right in. But it makes more sense to obtain new AN glass already sized and edged to your specifications, or else the equivalent from an old 8x10 enlarger carrier.

Koraks opinion is just that - his own opinion. With printing paper getting more and more expensive, I wouldn't want to lose any of it to Newton's rings due to cheap common float glass.

Cutting down tempered glass requires a different kind of cutter wheel than ordinary float glass, and a different kind of edging. Either have a pro shop do it, or obtain the right gear yourself. Same applies to hard optically coated picture frame glass. I have tried the latter as a substitute for AN glass - it might work OK in drier climates, but didn't here along the foggy coast. Better than common float glass, at least. It's just like the difference between a plain glass camera filter and an optically coated one - the coated version stays cleaner and resists otherwise undetected condensed moisture better.

UV printers, however, might need special glass types to optimize UV transmission. Sandy King did a lot of testing on that front, relative to the different UV options and printing methods.

Free piece of scanner certainly did warrant any more than an attempt to cut it. For obvious reasons it’s not marked like most temper glass I’ve familiar with. My understanding that if you want to cut tempered glass is that you need to un-temper it, do your cutting and any other work then re-temper it. I’ll have to look into the equipment cut it while is still tempered, more out of curiosity, as I’m not familiar with it. As I mentioned I ended up with anti-newton glass in my 8x10 frame. The newton rings happened just enough to be really frustrating.

No "un-tempering" and "re-tempering" is involved. For basic handheld glass cutters you simply order the Fletcher version intended for tempered rather than regular glass. The wheel has a more acute V-angle. But that's still a risky proposition unless one has a lot of practice doing it that way. I use a big dual-rail Fletcher industrial sizing cutter with interchangeable glass wheels (plus acrylic scorers). Glass cutting fluid is used in both cases; but the spring tension has to be readjusted. I have other special glass tools on hand, plus lots of plastic equipment. Practice is essential.

At one point, I had over twenty different kinds of AN glass option samples on hand for testing - back when there was a still a number of sources. As I understand it from forum comments, the AN glass Kienzele has been supplying isn't even properly edged. Lacking a proper pro edger, one can simply use ordinary fine black silicon-carbide emery cloth to ease the edges from risky sharpness.

It helps to do fresh web searches from time to time. I notice several new sources for replacement AN scanner glass, including a quite affordable one for smaller sizes listed on Etsy (can't vouch for the quality). But alas, I also ran into some clown on UTube claiming all AN glass (including for photographic purposes) is just a marketing scam. UTube can sometimes be a Wild West of misinformation. I'd have to shut down my darkroom without AN glass in every single carrier.

Even in some of my best color "coffee table books" I can detect Newton rings in the skies, which somehow evaded all their offset powder and so forth. When working with multiple sheets of film in register, as was once done in the printing industry, it just multiplied the risk itself. Basic contact printing is a lot simpler.

Going hi-tech, look up a company called Vue-Guard, which specializes in Anti-Newton optical coatings. Probably not realistic for our simple needs, but informative anyway. I do have one set of coated rather than acid-etched optical AN glass, specially made by Zeiss (which I bought as leftover surplus - had to be cut with a tempered glass wheel; worked quite well in conjunction with my 8x10 cold light, but wouldn't work for UV printing).

I don't get it. I see no surfeit of non-functional flatbed scanners with clean glass just laying around waiting for someone to claim the glass by prying it from the cold dead fingers of the scanner frame. It's easy enough to just buy a sheet of glass of whatever specification and size needed.

A decent sheet of new true 8x10 or 11X14 AN glass is going to cost around $100 - well worth it in the general scheme of things. Thin fuzzed-up picture frame glass is something else entirely. A suitable piece of slightly textured nonglare acrylic plastic might run you anywhere from free to $5 in a plastics shop cutoff scrap bin.