Printing Glass Plates: How to avoid breakage?

[G Benaim]

Hello,

I'm in the process of preparing to print some 80-100 year old glass plates, and wanted to ask folks with experience how they print them. I plan to use azo/lodima, and am worried a heavy piece of glass which I normally use may break these old plates. If I use single-weight paper, are there any good alternatives to applying pressure, or is that really the only way? ANy of you have bad experiences you'd like to tell me about? These are small, from 5x7 down to somewhat smaller than 4x5. Thanks.

[Jim Noel]

I use them in place of the glass in an old fashioned contact printing frame. No breakage so far.

[G Benaim]

Hi Jim,

Not sure I understand you, do you mean you remove the glass from the contact frame and then use a glass plate without a top glass? If so, what exerts the pressure needed for good contact?

[Alan9940]

I would try simply laying the glass plate on the paper. I've done this for proof prints to be filed with the glass plate, but have yet to attempt a fine print from one. If some pressure becomes necessary, I can't imagine that gently laying a piece of plate glass on the plate to be printed would cause it to break; especially if the plate glass is the same size. But, please, do what you think best as it sounds like you have irreplaceable plates.

[domaz]

Hi Jim,

Not sure I understand you, do you mean you remove the glass from the contact frame and then use a glass plate without a top glass? If so, what exerts the pressure needed for good contact?

The spring at the back of the contact frame would exert pressure this way- but the caveat is the frame's rebate for glass needs to be the same as your negative- which is likely an issue. You can use a regular contact printing frame with the glass still intact too, it's a bit riskier I suppose but commonly done.

[Vaughn]

I use them in place of the glass in an old fashioned contact printing frame. No breakage so far.

I use some contact printing frames from B&S. I use an piece of black matboard for normal printing -- seems to have more space for printing glass plates than others I have used.

Another option would be a vacuum easel (different from a vacuum frame...no glass) that would hold the paper completely flat, then use just the weight of the glass plate itself to lay tight against the paper.

OR...use soft foam below the paper, put the glass neg on top, then glass over that. The foam would allow for minimal pressure against the neg and still make good contact.

With the age of your plates, I would inspect them carefully for defect in the glass -- especially on the edges. I have never had the glass of the frames break during use, but it has been newer glass with sanded edges that would be less likely to break under stress.

[Jim Noel]

Hi Jim,

Not sure I understand you, do you mean you remove the glass from the contact frame and then use a glass plate without a top glass? If so, what exerts the pressure needed for good contact?

Yes. The spring back exerts the pressure needed.