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View Full Version : Acrylic Latex for a base coat?


paintbug
01-21-2002, 10:55 PM
For almost two years now I have been using Acrylic Latex House paint as a gesso in preparing surfaces for oil paint. Sometimes I add a bit of acrylic artist paint to it as a tint. So far, for me it has worked well and to my relatively inexperienced eye it seems just fine. I have been told this is wrong and I should be using regular acrylic gesso. My question is why? Isn't the purpose of gesso to protect the surface from the oils?
Thanks in advance,

Einion
01-22-2002, 01:52 AM
The basic issue here is longevity - obviously in practical terms it does in fact work quite well. Considering the makeup of most acrylic paints how they age themselves is not really that much of a problem (alkyd house paints would be a different story entirely) so while I wouldn’t recommend it, it might be a reasonable and cost-effective priming method.

The main issue one sees discussed with any acrylic material used as an underlay for oils is one of delamination (peeling of the oil layer), and there have been examples of where this has happened in practice, considering the timeframe of the availability of acrylics this is a worry. There are ways to minimise this problem by forming as strong a mechanical bond as possible, two main methods are in general use - sanding the primer or mixing in something like chalk dust or diatomaceous earth to add tooth (don't use talc). Both methods help the bond between the oil layer and the acrylic which tends to be rather "slick" on a microscopic level - you might read mentions of the surface of dried acrylics after the evaporation of the water where the globules of water were in the emulsion little hollows remain after they are gone but this does not appear to offer enough for the oil paint to grab onto, at least consistently. It's worth remembering they usually recommend sanding between layers of acrylic primer and this is the material bonding with itself. As a general rule of thumb I think if an acrylic surface is even slightly glossy (as many commercially-primed surfaces are) this is potentially a problem if you use oils.

Depending on whether you like to paint on canvas or board I would choose whichever of the two methods is most appropriate as obviously sanding is not the best choice over the texture of canvas, but it's worth considering that adding varying proportions of additional material will weaken the acrylic film to some extent. Whether this is a problem is dependent of a number of factors.

Einion