I have done a bunch of paintings on canvas using the inexpensive acrylic paints that come in those little 2 oz bottles, and now I'm worried that they may fade.  Is there some way I could treat the canvas -- like apply a glaze or finish to it - that will help them last longer?

 

~Marney 

Add a coat of poly-varnish with UV protection. It will greatly increase the longevity and lightfastness of your artwork. I recommend satin finish to make the least amount of visible change to your work.

 

Here's some info about paint quality and lightfastness:
 

You can check the ASTM (American Society for Testing and Materials- the UK version is BSI- Bristish Standards Institute) on the paint you use.

The ASTM has set standards for all artist materials, including lightfastness of paint. Ratings I and II are recommended as "permanent for artist use" They test pigments in artificially accelerated conditions with white light and in in desert sunshine.

Art materials manufacturers also test their materials, so if the product is new and ASTM hasn't rated it yet, the manufacturer almost always has a rating.

Basic rule of thumb- the higher the quantity of pigment- vs fillers and binders- the longer the lightfastness. 

Craft quality paints are often not rated, unfortunately. But many of the fillers included on this quality of paint actually help to preserve the color. Opacisizers for example- added so you can cover in one stroke - actually improve lightfastness.
 

 Allison, thanks so much for this.

I was wondering if the poly will smear the paint at all (esp if it's just a cheap craft paint?)

I also have used some metallic dye inks on canvas as well - wondering if the poly will work on that, too? 

Hi Marney, Since all acrylics are a poly-medium, once they are dry, they are set. Not so with inks and dyes - they differ with each manufacturer and according to the intended substrate. I've had some inks completely change color over time. If I have mixed media on a piece ( I make giclees on canvas, and then hand embellish them with oils, acrylics, inks, pastels, etc.) I use a resin based varnish spray (Grumbacher matte ). It's UV, museum rated, non-yellowing and wonderful protection for all these media. Marne

 Thanks so much for this helpful advice, Marne!