Updated: Nov 14, 2019
Like bunkers and water hazards in golf, every art medium has its pitfalls. The key to success is figuring out how to avoid them, or if you fall in, how to get out.
1. New layers reactivate previous layers of paint.
--Leave half-dry passages alone! Let them get really dry before you add a stroke.
--Think before you lay down a stroke; Commit to it and leave it.
--Place the wettest layers first, and use the paint drier and drier as you build opaques.
--Instead of regular gouache, use an acrylic-based gouache or casein, which doesn't reactivate.
2. Gouache changes value when it dries.
--Darks tend to lighten and light values tend to darken.
--This is only a problem for big, flat areas or swatches. In that case, mix plenty of paint when you cover an area that needs to be flat.
--If you practice enough, you get used to it, and it becomes second nature, like keeping a violin in tune.
3. Surface is fragile and easily ruined.
--Paint in a hardbound watercolor sketchbook to protect it.
--For separate sheets, use plastic sleeves, paper flaps, or frames with glass.
--The matte surface is one of gouache's virtues. It photographs well, and is receptive to drawing media, something you can't say for many other media.
4. On a hot, dry day the paint dries instantly.
--Squeeze out the paint on a damp paper towel on the palette. Spritz it with a sprayer.
--Use a priming with a sealed surface, such as gesso or casein. That will reduce absorbency.
--Shade the painting and palette with an umbrella or diffuser.
5. The opaque paint covers up the underdrawing.
--Start more transparently and gradually build up opaques.
--Keep track of the eye level, vanishing points, and a few key points, and construct forms with the brush.
6. "I'm hesitant to get opaque enough" or "I can't get opaque enough."
--Use pure watercolor (or a gouache without opacifiers) for the transparent bits. Then bring in plenty of opaque gouache or titanium white in mixtures.
--Experiment with different brands; avoid student brands, which use fillers to extend the pigment.
--Get in the habit of re-squeezing palette colors that have run out. Don't run on empty.
--Do a grisaille over a bright yellow acrylic gouache underpainting. That forces opacity.
7. There are almost too many vivid colors to choose from.
--Too many colors on the palette leads to troubles with middle-value-mumbling and disharmony.
--Use a simple warm-cool palette. You can paint almost anything with six or fewer.
--Another option is to pick a red, blue, and yellow at random (plus white and black) and paint a picture with those colors and no others. Then switch to another primary palette.
This article was first published on http://gurneyjourney.blogspot.com/2015/06/the-seven-gouache-hazards-and-how-to.html