Terry, I have tested perhaps 2 dozen different papers at various times by
marking off, say, a 30 centimeter distance on the fresh paper, then
soaking the paper (in hot or cold) water and re-measuring. Every paper
shrank. After the paper dried, I soaked again, dried, and remeasured. In
most cases the paper changed yet again, getting either bigger or smaller.
The differences were often slight, but even the width of a pencil line
"out of register" is enough to destroy delicacy of drawing in a
photograph, ie., blur what you wish to make sharp, especially on smooth
paper. The effect is less evident or perhaps not evident at all on *rough*
paper, which I try to avoid.
Sometimes the change is in one direction only, sometimes in both. I even
have one paper that takes gum exquisitely but gets bigger the long way
& shorter the short way when wet, reverses those changes on drying.
I will add that the change in dimension was a factor of the wetting,
rather than of gelatine sizing and hardening. At least on some 5 papers I
tested for that specifically, there was no difference between wetting
without gelatine size added and wetting with size and then formaldehyde.
And Terry, I think you deserve a reproach for dismissing questions along
these lines. What the non-initiate takes for a trivial distinction may
look crucial to the pro -- and vice versa -- as you yourself are first to
illustrate in other instances. Incredible as it may seem, even I myself
in feckless youth shrugged off variables that I learned later, to my
chagrin, were major.
Judy