20x24" contact printing frame

[David A. Goldfarb]

The Formulary frames are inexpensive, but I wouldn't get one for 20x24". The back attaches with clamps that go around the perimeter of the frame, rather than leaf springs that apply pressure from the center of the back. I tried an 8x10" frame of this type at a workshop and didn't feel I was getting good enough pressure in the center of the frame.

Some contact printers say that for anything larger than 11x14" it's better to use a vacuum easel.

[RobertP]

Bostick and Sullivan frames are very nice. Their frames are always somewhat bigger than the posted size. An 11x14 will be something like 12x15 if I'm not mistaken. Robert

[boyooso]

my "20x24" frame was made the size I wanted to accommodate the paper size of my choice.

Doug Kennedy makes frames to order, so you can get exactly what you want!!!

Corey

[Falkenberg]

Doug Kennedy replied to my mail and recommended his student frame. Do any of You have any experience with them ?

[Ole]

I have a monstrous 40x60" vacuum frame I'm planning to use, as soon as I manage to clear a large enough space to pull it out of storage.

[Nicholas Lindan]

Originally Posted by Falkenberg

Does anyone know about who produces a 20x24" contactprinting frame ?

For that size you need a vacuum frame.

A conventional design frame won't be able to put enough uniform pressure on the materials to assure really good contact. If the spring force holding the back on is 50lb then the pressure holding the materials together is only 1/10 of a lb per square inch. But the pressure won't be uniform because the glass will bow, so some places will have very little clamping force.

A 20x24 vacuum frame has a clamping force of 14 lbs per square inch and puts no force on the glass. The total force is 6,700 lbs and the pressure is uniform.

You shouldn't need to pay much for an old vacuum frame. They are a bit scarcer now than they were 10 years ago when all the print shops were throwing them in the dumpster.

Another thing to consider is a "plate maker".

As hobbyists are now the largest consumers of these products, the smaller units command premium prices on ebay & co..

[sanking]

The best solution for 20X24" and larger contact prints is a vacuum frame. However, if you are printing sillver with a point source or collimated light source it is possiblel to get good results with most contact printing frames, or even a thick sheet of glass laid over the negative and paper. I print AZO this way by simpy suspending a 5 watt night light some 40 inches from the frame.

However, if printing alternative processes with a diffuse light source such as bank of BL tubes it is almost impossible to get acceptable results with a contact printing frame in any size over 11X14. In this case a vacuum frame is essential ffor best work.

Sandy King

[boyooso]

I print 24x30s and 30x40s with home made contact frames. I absolutely can't use a vaccum frame. It applies too much pressure. Too much pressure can push moisture from paper into the film, as you can imagine this is a problem.

This probably isn't a problem if you let your paper get bone dry, but my results are less than optimum with bone dry paper.

I would trust Doug's recommendation. I don't know if my large frame from him is or isn't a student model or not, but if is a great frame!

Good Luck

Corey

[2F/2F]

Well, my Formulary 20x24 frame works fine. Have used it for all sorts of things and it's sharp enough for me. At $99, what the hay.

[RobertP]

Corey, Vacuum pressure can be adjusted I'm sure. Plus I have printed with pieces of transparent archival grade polyester film (from Light Imptressions) on both sides of the paper. This helps contain your paper's humidity and protect your negatives. The stuff works great. Robert