Paintings without a varnish layer collect dirt in the interstices, which can rarely if ever be removed without damaging the paint layer. It has been suggested to display or store these works behind glass or in a dirt controlled atmosphere or, alternatively, to possibly compromise their appearance with the application of a varnish. There are concerns as to whether or not to varnish acrylic paintings and many artists insist that their acrylic paintings be unvarnished. Acrylic resin proprietary varnishes have similar solubilities to those of acrylic paint. This necessitates the use of solvents which might damage the paint layer for their removal.
Acrylic paint is also soluble in the solvent used to remove traditional varnishes.
Thus, varnish application to an acrylic painting requires serious consideration. When a painting is being moved about, a frame will protect the sides. A frame should be large enough to receive a painting and permit it to be keyed out when necessary. It also should be in sound condition. Frames can display paintings with or without a protective glass covering.