Preserving waterbased canvas prints ?

[BeaLola]

Hi

My DS has done a picture for grandpa onto one of those cheap canvas blocks you can buy in wilkos/the works. The paint is watrerbased. Is ther anything I can spray over it with to preserve it ?

TIA

Hairspray.
Paint on PGA glue

acrylic matt varnish from an art shop. it's specially sold for paintings but can't remember the brand name.