How To Avoid Paper Curl
Imagine this. You are preparing prints for a highly respected exhibition. It is now in the fifth consecutive day of rain. You process the prints in your usual way--everything seems to be going well throughout the entire chemical process. Using a new box of Agfa fiber-based paper, you make your 16x20" prints and hang them to dry in your basement, then plug in a dehumidifier, figuring that it will take some of the excess moisture out of the air and the prints will dry more rapidly. Once dry you put them in a portfolio case and bring them to where you use a dry mount press. It is still raining. Back home, you carefully place the images into a portfolio, placing them flat on a table.
Two days later you cut your mattes and notice a few buckles in the prints but figure that once you get them into frames they will be fine. Wrong! With art tape you tape the four corners and they are ready for framing. It is still raining. The next day you notice that in certain lighting the buckles look worse than they did. With all the wrinkles your self-portraits are starting to look like Dorian Gray. What to do? If you wet them and put them into the press a second time, the already stretched paper may crease. The option of re-washing them and pressing them again is out of the question. There is no time. So you end up cutting smaller mattes to hide the edges, then packing an extra piece of matte board and a piece of foamcore behind the original matte. The prints look like lasagna in the frames. It is still raining. This is what happened to Sonja Rodrigue. Is it the weather, or an operation error? Let's ask the experts.
Tony Decaneas, head of Panopticon, a black and white photo lab and gallery in Boston, Massachusetts, says: "The problem is that fiber prints really need to be dried in a controlled environment that is moist. Agfa and Ilford, both European manufacturers, make the papers I am most familiar with and I think the ambient humidity in the natural environment where the papers are made is a lot higher than here. Using a dehumidifier to speed up the drying is a great idea but the consequences are exactly what happened to Rodrigue's paper. If you dry fiber prints too fast they cockle, meaning the emulsion dries at a different rate than the paper base that supports the emulsion. You want to try to make it as uniform a process as possible. We dry our fiber prints emulsion side down on fiberglass screens and have several humidifiers throwing moisture into the surrounding area where the prints are drying. The curling problems usually manifest themselves in the dead of winter when it is cold and the moisture is kind of sucked out of the air. We have complained for a long time to both Agfa and Ilford about the problem but in fairness to them, there is probably an adverse consequence on the other side. If they fix the problem for us what does it do to those who are in significantly more humid environments?
"We squeegee the prints first--if you just put them on the screens you will have pools of water that will create the same problem since those areas will dry slower than the rest. Our prints don't come out perfectly flat so we put them in a vacuum press at a very low temperature, about 100, for about three or four minutes. Now, if you took these prints and put them up in Alaska and left them in a cabin they would contract and expand because of the range of weather. Even archively matted photographs that are perfectly flat at one time of the year will move and if things are properly matted this is a healthy thing because it assures a real long life for the photograph when you allow it to contract and expand. When you dry mount a print you take away that provision. For mounting we make photo corners using acid free vellum or barrier paper that holds the paper but allows it to move."
Sal Lopes, master printer of both platinum and silver prints, says: "Paper is always more limp when the weather is damp so Rodrigue should not have hung her prints. Drying the air out with the humidifier made her prints worse because the more moisture in the paper the less tendency it will have to crease and curl. Since prints will curl a lot more when the air is dry, you always want to dry silver prints on a fiberglass screen.
"Putting the print face down begins to defeat the natural tendency of the paper to curl on the emulsion side. With platinum we put them face up because with some papers you might see the screen pattern. However, there isn't the curling problem with platinum because there isn't a gelatin. If there is a slight curling it comes out easily in the mounting process.
"To squeegee prints I suggest that one should get a piece of quarter inch plexiglass, larger in both dimensions than the largest print they will be making. You can get a long winter windshield replacement wiper blade in an auto supply store. The winter ones covered with rubber are very benign and do nothing to the paper. If you are worried about it just mix up a little bit of PhotoFlo and soak the wiper to soften it up. Put the print face down and squeegee it--then squeegee the piece of plexi to get the water off and turn the print face up to squeegee that side. Keep everything super clean and rinse the plexi and the wipers well before using them again. The prints can then be put on the screens and you can come back tomorrow."
Linda McCausland, owner and director of Exposure Lab and Cape Cod Photographic Workshops, Eastham, Massachusetts, says: "The biggest success I have had with prints buckling is to keep them in as much humidity as possible. Every photographer who is working with fiber in a working darkroom should be aware of the amount of humidity. Rodrigue was in a situation where it was raining for five days and turning on a dehumidifier made the prints dry faster. Prints have a life of their own. After squeegeeing the prints on a piece of plexiglass I place them on the screen to allow them to get air from both top and bottom. I want to dry them as slowly as possible and I nurture them until the point just before they almost feel dry to the touch, then put them on non-acidic blotter paper under heavy pressure to press them flat. With the expansion and contraction of the paper it may change shape so if you can catch your prints before they are thoroughly dry and dry them under pressure for that last bit, they will lie flat. Rodrigue pressed them and when she brought them home they may have absorbed water from the moisture in the air and that changed their shape again. I have had prints come out of the press on a rainy day and they may curve up but they retain their rectangular shape and don't buckle. It is only when they go from wet prints to that initial drying stage where I have had scalloping on the edges and what I do is re-soak the print entirely for an hour or more so every part is wet. I check on it like a cake, just till it gets to that critical point. The larger your prints are the more difficult the drying process is. By the time you get to 16x20 or 20x24 you have to give round the clock nursing care.
"Also, the edges dry first and then the middle, so if I wait for the middle to dry, the edges have gotten too dry and the scalloping happens. The edges and the middle must dry in a proportionate manner. It's a good idea to keep a little spritzer bottle and if you see the edges start to wrinkle you can either spritz the edges or re-wet the entire print. If you are preparing for a show and running out of time and trying to press your prints flat because you are putting them in mattes, and if the edges are drying faster than the middle, then you can spritz a very fine even mist with a plant mister."
Shutterbug maven Bob Shell says: "I have even ironed prints or put them back in the dry mount press and heated them up again. It might crease them so it must be done very carefully. A lot depends on the person, the environment, and the paper. The amount of moisture in the air is important for film as well. I have a friend who lives in Las Vegas and it is always so dry there that at times he comes into his studio and the prints are curled up like a pig's tail. This dilemma is common for anyone who uses fiber-based paper. Resin coated paper doesn't do that but it is not considered archival and most serious printers don't use it even though Ilford and Kodak say the latest versions are just as archival as anything else. But people have a prejudice against using them and most galleries won't accept them. I dry my prints on a plastic screen, putting my paper between two layers of screen, one on top of the other, and clamp the screens together. Because it is restricted, the paper doesn't curl--it may be a little bit wavy and I stick it in the dry mount press to get rid of that. Then they are just hinged at the top."