>>5924115Touch-dry is usually a few days at most for the slowest drying, oil-greedy pigments (e.g. ivory black); less than 24 hours for umbers (pure PBr7, because of the manganese IIRC).
I *think* an issue with varnishing too early is that the varnish can prevent lower layer to oxidize properly. Perhaps using some oil in the varnish could prevent that, but then, it would be incredibly difficult to remove that final "varnishing" if need be.
Another related issue is to prevent your painting from collecting dust.
If I were you, I would contact Gamblin and ask them questions about how to use this varnish, why can you use it even if the paint isn't fully oxidized, etc. If they can't provide you with solid answers, then you'll know to avoid buying Gamblin stuff in the future ;-) Refreshing liberalism.
And I would look at a few books, e.g. by Xavier de Langlais and similar, who have done extensive research and testing on technical aspects of oil paintings.
