Product Reviewed: Gamblin FastMatte
Summary: Ideal for underpainting and suitable for all artists working in oil. Not solvent free.
I think most experienced oil painters are aware that the "fat over lean" rule is one of the few true rules in oil painting: paint used for laying out, massing in, or blocking-in on a canvas should contain little oil (or other medium). Each subsequent layer should be thicker and contain more medium than those underneath it.
The "fat over lean" rule is important for the integrity (and thus the longevity) of oil paint layers.
What I like about Gamblin FastMatte is that it specially formulated for use in underpainting. You can put it on in thin washes, or even lay it down in relatively heavy amounts, and be able to safely paint over it.
My favorite Gamblin FastMatte colors
Texture-wise, it is a stiff and gritty paint, rather like a thick gesso. I use it thinned with solvent for laying out and for the first layers that I put on the canvas.
Most notably it 1) dries overnight (at least, most of the colors do), 2) sticks to the canvas, and 3) dries to a flat matte finish which the subsequent layers of paint can grab onto.
A monochrome underpainting done with Gamblin Fast Matte
There is a range of colors available, although I tend to stick to raw umber, yellow ochre and transparent red oxide.
For the most part, I will end up painting over all the areas of FastMatte with regular oil paint, except where I choose to let some of the underpainting show through for effect. However, there's no reason why you couldn't execute a painting entirely in FastMatte—you would just have to accept that the finished piece will have a more unfinished look that something done in the traditional way.
Unless you work on large paintings, I'd recommend staying with the small 37 ml tubes. Like most alkyd paints, these tend to stiffen after being open for 12 months or so and a large tube is likely to end up going to waste. You'll want to replace them with a fresh tube of paint every so often.
In summary, this has become one of the most important paints in my palette. I strongly recommend it for all oil painters, even for those who like to work alla prima.