Friday, May 26, 2017

Casein Emulsion and Varnish

Julien from France asks:
"I've finally bought Richeson casein online, still quite expensive [to import to Europe], but quite cool, actually different from gouache or Holbein's Acryla Gouache. My question is, have you used the Shiva casein emulsion or varnish, and can you use it with gouache?

First, a little background. For those who don't know, when you buy the emulsion separate from the paint, you're getting the liquid glue-like binder that holds the pigment together. Casein emulsion is a water-soluble, milk-based protein in liquid form in a can or jar. It's the same stuff that they use to formulate the paint.

Shiva is the company that originally made casein paint. The company was bought by the Jack Richeson company, which markets the product under both the Shiva name and Richeson brand, but I believe they're the same product.

Detail of Skysweepers, painted with gouache with some acrylic medium

In answer to your question, I have only experimented a little with the casein emulsion. I don't see any reason why you can't use casein emulsion with gouache. It would make gouache behave more like casein. You could even use acrylic medium with gouache. I used to do that a lot, because I liked the opacity of gouache, but I wanted it to have the sealed surface of acrylic.

I have used the casein varnish made by Richeson, which is a liquid brush-on varnish. As far as I know, they no longer make it. I found that it doesn't work well with watercolor paper because the paper is so absorbent. It just soaks the varnish up, so it requires a lot of coats before you start getting a gloss.

But on a panel, the varnish develops gloss with just one or two coats. The varnish is helpful for bringing out the depth and richness of dark paintings. If you're using paint with a matte surface, dark passages are prone to looking chalky. I find that the matte surface of gouache or casein is better suited to more high-key palettes.

If you want to varnish a gouache or casein painting, you could use a spray varnish, but keep in mind that once you apply a varnish, the surface is closed, and you wouldn't want to paint over it again with either casein or gouache.


gyrusdentus said...

is there a reason why you do not opt for acrylic when wanting opacity,shine or no shine and layering?

Terry Stanley, The Art Lady said...

Hi Jim - Terry here putting in my unsolicited 2 cents of knowledge from my years at Richesons. Richeson Shiva Series caseins are indeed one single product line. Emulsion info: Actually is to be used to make your own casein with pigment, mixing the emulsion as you do with egg tempera, then thin with water. Some people will use the emulsion as a medium and it's fine to do that except you 1) may extend drying time and 2) will lose the lovely matte finish of the paint, which is why casein was so prized by illustrators - the matte finish reproduces beautifully. Casein shouldn't be varnished (or finish of some sort be applied) before it is completely cured, which can take up to 4-5 weeks. Varnish is actually unnecessary which is why it's not made anymore. If you insist on varnishing, an acrylic one will be fine. Do NOT use an oil varnish as it can cause adhesion issues, orange peeling, etc. Casein on panel or other rigid support is meant to be buffed. Once completely cured, take an old t-shirt rag or other non-listing cloth and gently but vigorously rub the surface. A lovely satin-ish sheen will come to the surface and actually protect the painting. Properly applied to an acceptable, prepared painting surface, caseins weather time even better than oils. If you use paper as your chosen surface, it is recommended that it be framed under glass.

James Gurney said...

Thanks, Terry, that's all very helpful info. I've noticed that the cure strength of casein really increases day by day after it dries. I remember you told me about buffing, and it's a great solution, giving kind of a soft sheen without too much gloss.

Gyrus, I actually like weaker emulsion strength for opaque painting, plus the ability to reactivate the surface of gouache. However, I do use acrylic, especially for painting maquettes.

Daniele Guadagnolo said...

Hi, Terry, thank you for these insight about casein painting.
What would you suggest as a rigid support for casein? As I previously stated here on GJ, I tried painting on an acrylic gesso primed panel but did't like the surface. The first layer felt very slick, and it also reactivated very easily compared to works on paper.

Biff said...

I have had instances where casein comes out of the tube too dry. In that case I have successfully mixed in a little casein emulsion. I have also found it effective to transfer the emulsion from the original large jar container to little "GoToob" squeeze bottles which makes it more portable and prevents it from drying out in a container. If you fill up the GoToob initially, air doesn't get in as you use it (the GoToob has a little flap valve) so the emulsion stays fresh.