Heat Press Troubleshooting

[Michael W]

Hoping for some tips on how to get around a problem. I'm using a heat press to flatten fibre prints - there are sixty of them, 16x20 inches, Ilford MGWT. The prints were air dried and are reasonably curly so we want to flatten them. Using correct procedure with the heat press, most of them are coming out fine. However there are about fifteen prints that are quite wavy along the short edges. When we put these through the press they came out with obvious cracks along those edges. We stopped after this happened to two prints, but now have the dilemma of how to proceed. The only thing I can think of is to rewash the prints until hopefully they lose the wave, then dry them and hope they end up in a state that enables them to go through the press OK. I'm just wondering if anyone else has encountered this scenario and if there are any known solutions. Thanks.

[Andrew Tymon]

I would rewash them and dry them slowly. Prints tend to curl if they are dried too fast, they emulsion side tends to dry quicker hence the curl. You could also dry them pegged back to back on a clothesline. Are you using drying racks?

[Erik Larsen]

You might try some steam from a tea kettle on the back of the print to relax the paper in the curly edges. Then stick back in the press when the moisture from the steam is dry enough to not cause problems in the press.

[bob carnie]

To add to Erik's response

You will need to raise the humidity in the mounting room as this is a known issue with low humidity conditions... I hate mounting hot prints in the winter as its really dry , so we pump up to about 50% with a portable room humidifier and it does the trick.

[Michael W]

Thanks for the replies thus far.
It is pretty humid here in Sydney, but the prints are very dry, having been made last December.
They were dried on racks, face up, which is how I will dry them again.
Can't use pegs as the image goes right to the edge of the paper, so can't risk any marks.
I will also test one with steam.

[Mrportr8]

The key to flattening large prints is to do it slowly, in stages. You can start by placing a board (with a lyer of paper on them as cushion & 1/2" (13mm) plywood, 1/4" (6mm) masonite, etc.) over them and slowly add a couple of books after a day or two. Then place them in the press for a few minutes with a light pressure. Remove them and let them cool face down on a clean surface under the same board you used previously. Then repeat the process and after about three or four sessions in the press with light pressure do one final run at full pressure. Another option would be to re-wet them with a flattening agent which will help to stabilize them.

[Renato Tonelli]

You may want to flatten them soon after the have dried or place them under some weight until you can get to them.
I have had a similar experience. Leaving a generous white border also helps - trim 2cm all around after flattening.

[Michael W]

The test print that I rewashed on Saturday had dried quite flat when I returned on Monday. Flattened easily in the heat press, so that's good news that a wash can get rid of the waviness. This afternoon I have rewashed the remaining wavy prints and will check them tomorrow.

[Michael W]

Yeah, in retrospect we wished that we had bought 20x24 and then trimmed to 16x20, but we didn't anticipate this problem.
Another thing that is interesting is that the same paper is drying quite flat in the current hot and humid weather, but dried really wavy a month ago. It must have been a drier heat then.
I have very little experience with heat presses so I'm learning a lot of new stuff.

You may want to flatten them soon after the have dried or place them under some weight until you can get to them.
I have had a similar experience. Leaving a generous white border also helps - trim 2cm all around after flattening.

[don mishler]

"They were dried on racks, face up"

I was taught to dry fiber prints face down. Since the paper wants to curl to the emulsion side the weight of the paper reduces the curl. It makes a big difference. Of course you want to keep your screens clean.


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