I bought a few acrylic primed canvas pads to do oil sketches. I noticed that oil has intruded through the ground and there are oily (yellow) patches on the back, and yes there is some sinking in. In the future I will put a double ground on them before I use them.

Some of the sketches I want to develop, and eventually glue onto panels with archival non-shrinking PVA. How bad is it to have oil get into the support? The first layer(s) of paint look absorbent and I’m using bodied oil to reduce the sinking in as I layer, but I’m expecting more oil will sink in as I go. Would it be better to mount the painting now so that the PVA fills the fibers before oil can infiltrate?