This week it was time to coat the plates covered with resist with caustic soda. By now the resist has dried. (No picture of this but here was the plate covered in resist.)
You leave the caustic soda overnight to bite into the plate.
Next week we will print the plates, and Steve will show us how he washes the caustic soda off. Apparently it turns the surface of the lino into sludge. Lovely.
Caustic soda is very toxic. You have to wear gloves, breathing mask to mix it, and eye protectors to apply it to your plate.
It has to be mixed in plastic containers with a plastic spoon or wooden mixer, as it reacts badly with metal.
You pour water into a container, and mix in two heaped tablespoons of the caustic soda. The container becomes hot, and gives off fumes at first (stand back and don't breathe them in).
Then you mix in wallpaper paste, to make it sticky.
Then brush it on to your plate with a nylon brush, in any manner or pattern that you fancy. The more you apply, the stronger the bite will be.
Steve leaves his plates in the bath overnight and washes it off the next day with water.
In the meantime, I took a quick proof of the key plate (this one won't have caustic soda on it) just to see how it's looking. The water is looking a bit clumsy to me. Will have to work on it some more.
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