Here’s what you can do James. 1st Option: Leave the Acrylic to dry and use very cheap hairspray over a test piece canvas or canvas material with a bit of paint not a prized piece of art work. (Preferably ones labelled as Tesco’s Hairspray) 2nd Option: Make sure yer canvas is lying flat, use a PVA mix with a bit of olive oil mixed in and have cling film on the edges of the canvas, after 15 minutes remove the cling film to remove excess glue. Once the glue is dried then in theory it should give a transparent layer over yer art piece however ‘canvas’ is very coarse material so it may not work and can cause damage to the paint. 3rd Choice: Use a weak polish or glass cleaner at 5 minute intervals on every bit of the canvas. Apply gently but to all bits of the canvas. (just a theory) Final Recommendation: Just get a clear plastic or glass cover. (Can’t think of anything else) Hope that helps P.S – Mainly use hairspray with chalk on paper found on school art books.