Your Questions on Materials and Techniques

You all have been asking some great questions about materials....

Kent Strabala asks: "Can you please tell me the main differences between gouache and casein? I know how they're made, i.e. gum arabic vs. a milk binder, but I want to know the differences in how they lay down, are used, and how they look when a painting is finished."

Jack Richeson Casein 6 Pack with Brush Set

James Gurney Kent, the biggest difference is that gouache remains soluble after it dries. Casein, because of its milk-based binder, resists reactivation after it's dry. Casein also lays down differently. Casein has more body and feels more like oil paint as it comes off the brush. Unlike acrylic, it doesn't get sticky as it starts to set up, because its emulsion is weaker than acrylic polymer. Both casein and gouache dry with a matte finish. Gouache is more delicate and more suitable to extremely fine details. The final difference is that gouache tends to look better in transparent washes, since most gouache is just pigment and gum arabic.
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Sros6 asks: "What brand of flat brushes are you using?"

I like synthetic flats in varying sizes. I'm mainly using the Jack Richeson pocket plein-air brush set and some cheap synthetic "Artist Loft" brushes. I find even those latter mass-produced brands are often very good, but watch out, because sometimes the ferrules fall off and you have to glue them back.
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Frances Wilcock asks: "Do you prime with casein to seal the paper or just for a colour wash? I have used gesso with gouache, which gave a somewhat rough surface, and matte medium (which I didn’t like much as it felt too slick). What would be the nearest alternative to casein for those of us who don’t have it?"

I prime with casein mainly to set up for an interesting underpainting, and sometimes to cover up a failed start. Casein does seal the surface, making it less absorbent to the gouache, so you might not like it if you don't like the acrylic matte medium. The nearest alternative is Acryla Gouache (see next question).

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Naomi asks: "I wonder if acrylic gouache can be used in place of the casein and then continue with traditional water gouache?"

Yes. I often use Holbein Acryla Gouache for priming. It seals the paper but has a matte surface, which makes it receptive to the gouache.

Sunshinearts asks: "How do you carry your gouache tubes? Mine always have the gum Arabic come out and it becomes a crazy sticky mess."

James Gurney I just carry my gouache tubes in a zippered pencil bag, or one of those plastic sandwich containers. If you have trouble with the gum arabic leaking out the top, you can try kneading the tube with the cap on to distribute the liquid. Also, with gouache and watercolor tubes, you can clean off the threads of the tube and the cap by taking the cap off and using a damp paper towel and a toothpick.

Robert asks: "Do you ever start a watercolor portrait of someone with a detailed pencil outline drawing of their portrait first and then start painting? Or do you almost always start with large, simplified masses and then get the likeness and details of their portrait as you paint?"

James Gurney Robert, I don't usually have time for a detailed pencil drawing on location. However, I usually try to get the measurements right and try to have an accurate map or foundation to work over.

Dusty asks "I've seen you use those ShinHan Pass watercolour and gouache hybrid paints a few times and I'm wondering if all the colors are usable or if you just use a few because you can't get those pigments from other brands? Quality gouache is very expensive and these Pass paints are much more affordable in comparison."

James Gurney I haven't tried all the colors in the Shinhan Pass watercolor/gouache set yet. I just bring them out to replace other colors that have run out. When I head outdoors, I just bring a few colors at a time to keep my life simple, usually 8 or fewer. I'm just using a small mixing surface, and a small number of colors lends harmony to the final painting. I'll eventually work my way through all those colors in the Shinhan set. The only criticism I have about the ShinHan colors is that they tend to be too runny unless you massage the tube to even out the ingredients.

Bryan Coombes asks: "I'd sure like to know your thoughts on how you cultivate your motivation to paint and do it so often. It's so easy to put it off... I guess this is a 'success principle' question."

I'm just happiest when I'm doing art. There are always spare moments in the day, and I love the challenge of facing a difficult subject and capturing some aspect of it. I also like having something tangible to show for my time. I think the best tip if you keep 'putting it off' is to find a sketching buddy nearby and go out with your sketchbooks on a regular basis.
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Previous posts:
Gouache Ingredients: Info from Manufacturers
Questions about Gouache
Gouache Materials List