These are professional-quality trays with raised ridges on the bottoms
which makes paper easy to grab so you don't have to scrape prints off
the bottoms, as with smooth trays. They have ridges on the right-hand
side that keep solutions agitated randomly as you rock the trays.

Besides darkroom work, these trays are handy for alternative
processes. Shrink or size paper in them. Soak Gum prints in them.
Wash cyanotypes in five changes of water into which you've added a
little citric acid, vinegar or other acidifying agent, etc.-- you get
the picture.

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