Re: shrinking Masa
I think that shrinking in warm (not hot!) water is simply more effective and so in the safer side, though not very important due to the effect of the following gum layers.But if original sizing is already holding them in the same position relative to other fibers, why bother with them? Don't we just need cold (room temp.) water take care of those which are not so tightly bound to go on? That would be my take...
Perhaps it is easier to see because the surface is more uniform (no image, no shinings, etc.)? I should look at my gums, but now I am not at home.... The only effect you see on the image side is the gloss in the shadows...