Diluted with distilled water, PVA (Poly Vinyl Acetate) is a size or ground for fabrics. Used to prepare raw canvas for oils, conservation scientists recommend painters use PVA instead of rabbit skin glue. PVA seals the fabric but does not re-absorb atmospheric moisture. On materials like cotton and linen canvas, this prevents swelling and shrinking that often leads to paint cracking.
PVA Sizing has a neutral pH and does not yellow, plus it retains its flexibility and does not emit harmful fumes.