glass with high UV transmission

[revaz_kv]

Hi everyone!

Does anyone know what glass should be used for contact printing frame?
I mean, is there a glass with very high UV transmission? Since better transmission means shorter exposure time.

There seems to be little info on the subject.
Any help is appreciated!

[Michael A. Smith]

Regular glass is all that is necessary. I am sure there is special glass, but think getting it would be an unnecessary expense.

Michael A. Smith

[Shawn Dougherty]

The only issue I've had involving print frame glass was Newton's Rings. That was solved by using reflection control framing glass with the slightly textured side toward the negative. I work in a frame shop so just used scrap but it's cheap, a kind framer might even give you a piece. Take your frame in so they can cut it to size.

Shawn

[revaz_kv]

Thanks for tips!
So, regular glass is ok for a vacuum frame, which I hope to build myself

What about plexiglass? Is it better when it comes to UV transmission?
I am asking because I saw a guy on youtube using plexiglass for his contact printing frame.

[JSebrof]

As far as glass that transmits UV, don't they make those special UV lenses out of quartz-fluorite glass? I don't know where you'd get that kind of glass in sheet form for contact printing though, or any other form for that matter.

[Q.G.]

They use fused quartz or fluorite. Pure.

Normal glass is mostly (fused) silica, with additions.

[revaz_kv]

As far as glass that transmits UV, don't they make those special UV lenses out of quartz-fluorite glass? I don't know where you'd get that kind of glass in sheet form for contact printing though, or any other form for that matter.

Quartz-fluorite > sounds very expensive

What glass is used in vacuum printing frames which are for sale at Edwards Engineered Products? Is it a regular glass or something special?

[Shawn Dougherty]

Thanks for tips!
What about plexiglass? Is it better when it comes to UV transmission?

I remember reading somewhere that Plexi blocks more UV than regular glass. Naturally I do not remember the source. =) Might be worth checking into...

[Michael A. Smith]

We use regular glass in our vacuum frame.

Michael A. Smith

[Poisson Du Jour]

Calcium fluorite (CaF2) even better!

Failing that (by cost alone...) you could use an offcut of TruVue UV-retardant glass used in MGCF jobbing; most high-end frame shops use this, and all of my Ilfochromes have been framed under it since 1994.