I wonder if the need to fill the weave as well as wet the glass affects the ratio.

I assume 1:1 for the absorption factor of cloth itself then add some factors for wood absorption, and fill coats. Since the wood only absorbs once and the fill coats are only on the outside, the number of layers of cloth don't change these two factors. I think that something close to 1:1 works for each additional layer of cloth, so twice the cloth weight for each layer after the first layer is pretty good estimate.