I don't think it's quite that simple Terry. I think that what it really
comes down to is having a certain density of sensitizer on the paper.
I've found that something on the order of 0.75 drops of sensitizer per sq.
in. of coated area to be a good minimum target -- more than that won't do
any harm except to your wallet.
The Platine paper is not very absorbent -- it will not take this amount
of sensitizer in a single coat as some of the other papers will.
Therefore, it is necessary to doublecoat the paper to reach the necessary
density. I also find it necessary to allow this paper to dry naturally,
to allow the sensitizer to soak in a little.
I will, however, agree that the most grain free prints are made without
using any restrainer (contrast agents) in either the sensitizer or the
developer.
David Fokos