Diluted with distilled water, PVA size is a contemporary size for fabric support. Conservation scientists recommend painters use neutral pH PVA size on linen and canvas instead of rabbit skin glue.
PVA provides a good size layer that seals the fabric but does not re-absorb atmospheric moisture, swell and shrink like rabbit skin glue does. There are hundreds of different formulae of PVA.
Gamblin PVA Size is made from PVA that has a neutral pH and does not yellow. It also retains its flexibility and does not emit harmful volatiles.