Keeping the (Single!) Print Processing Plastic Tray Clean
By Lloyd Erlick,
April 16, 1998

Keeping a plastic black and white print processing tray clean is easy.

The beauty of the single-tray method of print processing (See Table of Contents, Technical Issues, on this website) is that no chemicals are in the tray for a particularly long time. This means stains and deposits have little time to form.

The worst stains in black and white print processing are usually from the developer. Commercial tray cleaners are available, but they often contain toxic substances like dichromates. The single tray method obviates the need (and expense!) for such materials.

Preventing developer stains in the tray is easy (as long as the single tray method is used, that is!) After each print is developed, the tray is rinsed. Simple. The stain never forms. With the single-tray method, rinsing is done by pouring plain water into the tray right on top of the print, after the developer has been poured out into its container. To rinse the underside of the print, the tray is rocked back and forth and side to side so as to cause a 'wave' to pass under the print. Describing it is like using words to teach someone to tie shoelaces. It takes only a few minutes to learn by doing. Thorough rinsing of the tray and print is quick and easy.

There is another benefit, too: carry-over of developer to the fixer is reduced. This is significant, because if developer finds its way into the fixer, the possibility of stains becomes very real. And because I use a non-acid fixer, this possibility becomes nearly a certainty. So my post-developer rinse serves two important functions.

Not all developers are clean-working, of course, although most commercially packaged ones are pretty clean. The worst-staining developer I've come across hasn't even been a proper developer. I bought some Glycin developing agent to mix up the Ansco 130 print developer, and discovered the Glycin was stale. No image, but plenty of stain, on both the sheet of paper and the tray. It pays to be sure of your materials. I frequently use the old Ansco 120 print developer formula, and find developer staining problems to be negligible. However, no matter how filthy-working a developer might be, its ability to stain the tray is severely curtailed by limiting its time in the tray.

The next worst stains are from selenium toner. These stains give the impression of being immovable, lifelong companions. Trying to clean them with a plain wad of paper towel and water is fruitless, and adding detergent not much better. But, add a little common laundry chlorine bleach to the wad plus detergent, and the stain disappears without even much elbow grease. The temptation to work hard at scrubbing is hard to resist, but really one only needs to keep swabbing the bleach around until the stain goes. It will even reach down into the grooves on the bottoms of some trays, or the little indentations some tray bottoms have to support a thermometer.

Wear protective gloves! Use cold water in a well ventilated area so the chlorine doesn't upset you. If you think you might splash bleach around, wear something to protect your eyes. Cleaning a tray probably requires about one tenth the amount of bleach used for a load of laundry.

Selenium toner stains in the tray are directly related to the concentration of the toner. It is extremely common for darkroom workers to use it at 1+15 to 1+20 dilution, or even more dilute. At this level, staining is very moderate. Many, many prints must be toned before a significant deposit is left. I often use selenium toner at a dilution of 1+5, and I find a deposit forms quite noticeably in only one printing session. But even so, it is seldom necessary for me to clean the tray more often than about every third session. This is an embarrassing admission, because good practice would demand cleaning it at the end of every session! Doing this with an ounce of bleach would be quick and easy.

If the interior surfaces of the tray are kept free of scratches, stains and deposits will be much easier to clean. They will also form much more slowly, because the rough areas are best for deposit formation. My Paterson 16x20 tray had five little rounded bumps down the middle of the bottom. They made little marks on the sheet, which were visible after the print was dry. Leaving aside the question of why a photographic products manufacturer would make a product like this, I took a sharp chef's knife and sliced off the bumps. After performing this surgery, I attempted to smooth the lesions with sandpaper. The resulting rough areas are the first to stain. However, I find that no developer stain gathers, because I do not let developer stand in the tray. Selenium toner does stain it, and the rough areas darken quite severely. They disappear quickly on contact with chlorine bleach.

It's entirely possible some people will find photographic chemistry that will stain trays and never leave. The world is full of exotic toners, and lots of them should not be used in stainless steel trays. So the life of a plastic tray is always in peril, but for normal print processing in plastic trays, the darkroom worker can easily keep the tray spotless and pristine.

Copyright Lloyd Erlick. All rights reserved.