Hi again and thanks for your answers;
I used brush and dried the paper/emulsion in empty boxes for photo paper.
After an hour it was dry enough to add on the second layer.
And there I left it and I hope to play with it tomorrow :)
The answer to this question is not so easy because it depends on many factors (in addition to temperature and air flow, relative. humidity also the quality and character of the paper, the method of applying the emulsion, hardener content, etc.)
Recomendation from Foma Bohemia for temperature 20 degrees Celsius and relative humidity 40-60%.
minimum 10 hours when emulsion is applyed with brush.
minimum 6 hours when sprayed. 6 hours for each sprayed layer.
The point is that the emulsion dries not only on the surface. This would cause problems by the use of developer etc.
Given time can be shortened with a faster flow of dry air when you use hair dryers or the like.
I went to a kitchen shop and bought stacking cooling racks. Not very expensive. I have a cabinet in my darkroom that I put them in with the paper on them. I don't want them to touch or they might stick.
I leave them a couple of days and have had good success. I use Rockland Colloid Liquid Light, but assume most of these emulsions are similar.
After tree dayes I used the paper.
Some of them were dry enough for use. But a few were to soft and the emulsion rambled (?) in the developer.
So I gess the emulsion need more time to dry in boxes.
Suppose I need to build a rack.
CD racks are useful for 4x5 too. People throw them out a lot. I've found them especially useful for students coating plates in large numbers.
A shoe box works for 4x5 glass plates. The box will warp from the moisture it absorbes overnight so I wrap it in a black cloth. The next day another box replaces it and the first one is allowed to dry.