Posts Tagged ‘Casein’


Sinopia Casein Gesso Update: Jar Problem

May 2, 2017

I’m interrupting my series of posts on the new painting to point out a problem I discovered today with a jar of Casein Gesso from Sinopia. This follows up on two posts I made in the past: one is a review of this product, and another was how I store paint containers like this upside down.

I bought this jar of gesso a little over a year ago, and keep it inside a drawer in my studio. I haven’t used it in awhile, but today I decided to open the drawer to try it out again, only to find the contents had leaked out. The lid was screwed on tight, but that wasn’t enough to stop air from getting in, and some of the contents leaking onto the drawer. Fortunately that was plastic, so it was easy to clean (that’s what that clean piece of gel is in the picture,) but I had to use a plumber’s wrench to get the lid off, and found that about 1/3 of the paint had dried out. That rounded disk inside the lid is about 1/2 inch layer of dried paint, and more dried on the sides of the jar. It had been stored upside-down.

As I mentioned in the article link above, I store containers like this upside down just for this reason. Screw-on lids of this type make very poor containers for paint, since air gets in easily. Even if this was stored upright, air gets in, and would have dried out the paint even worse. Some jars you can buy come with cushions inside the lid, sponges or thick paper, that help seal the jar. Another solution I’ve used in the past is to wrap wide tape around the outside. That has to be replaced frequently, but it’s better than throwing away paint.

Metal cans for paint make a better seal than a screw-on lid, unfortunately, a quart size can is the smallest available. Tubes are also better since the opening is smaller, so less air gets in. The best option is to use it up quickly. Prime several sheets of paper stock or canvas that you have on hand, and don’t store the left over paint for very long.


Homemade Casein Fixative

October 27, 2016

I’ve been meaning to make fixative out of casein for some time now, but until recently I haven’t done much art in a medium that need it. Today, I was in a conversation with an online friend about types of fixatives, and this subject came up, so I thought it was a good time to make some and test it out. Conclusion: it works very well.


If you’re possibly new to the term “fixative” and its use, it’s a coating that is added on top of dry media (charcoal, pastels, graphite, etc.) to keep it from smearing. Most commercial fixatives come in aerosol cans that use an acrylic resin. There’s a commercial brand of casein fixative on the market called SpectraFix. I’ve tried it, and it works okay; although, I’m not too fond of their pump sprayer.

I first heard of using casein as a fixative in a book about Paul Gauguin and his pastels where he learned this technique from Camille Pissarro. I later found a recipe for it in the Reed Kay book “The Painter’s Guide to Studio Methods and Materials.”
1 part by volume casein solution
2 parts by volume grain alcohol
5 parts by volume (distilled) water

The casein solution I used is the same as I always make for a base medium to start from. I describe it here in my most recent batch I made back in April. It has a couple drops of Thymol preservative in an 8 ounce mixture. It’s very easy to make. This batch came from raw milk, but it can also be made from dry casein powder, which I’ve talked about before. The grain alcohol I’m using is Everclear, which is 190 proof. A good clear Vodka could also work.

Mixing it was simple enough, so to apply it I used the Preval sprayer I wrote about a few years ago. I’ve used it occasionally for spraying primers and it works great. I found that the spray comes out with a little more force and volume than most aerosol cans I’ve used. As such, I knew to step back about 2 feet with the art surface upright, and move across the art in a quick sweeping motion; starting the spray off the art and finishing off the art.



The plastic sheet above has the fixative on it, and the sheet below it has none, so you can see how it turns the plastic very dull. When sprayed on paper, even black paper, I don’t see anything. Held up to the light, I can’t see any reflections. Each coat dries very quickly, under 10 minutes. When soft pastels were sprayed with two coats, I didn’t get any smearing.


At first, I got worried when I sprayed the grey pastels above. The whole image almost disappeared, but it came back as the fixative dried. It lost a little of it’s brightness, but otherwise worked fine. On the white paper sample, the color pastels didn’t seem to change value at all. It also works well on soft graphite pencils and charcoal.

I would have no concerns using this fixative on my finished work. I could also layer it; although, I would be reluctant to build it up too much – 3 to 4 coats max. The water content could cause paper to buckle, especially thin paper, unless it was stretched or taped down before the drawing was started.


Painting Sketch: Filing Her Nails

July 15, 2016

This was going to be just a monochromatic sketch with oil paint, but I’m now thinking I’ll take it a little further into a more finished piece, at least adding some more color.


It’s from on an old photo I took of my friend, Valerie, as she sat filing her nails. The background is all made up. I’m using a red ochre and naples yellow oil paint, thinned with casein medium. The surface is a canvas sheet, with acrylic ground, 12 x 9″.


Casein Made from Kalona Brand Milk

March 28, 2016

Here’s a follow up to my previous post, with me now making a batch of casein glue from the Kalona brand milk I bought. It looks like it will work just fine.

As a reminder, this milk is different than the sort normally sold at a grocery store here in the US. It’s non-homogenized, low heat pasteurized, and about the closest type to raw milk you can buy. Here’s how I made the casein glue from it:
First I poured 8 ounces of the milk at room temperature into a small pot, and heat it to about 150 degrees, making sure it doesn’t get over 190. I stir in two tablespoons of white vinegar. In a few seconds it congeals into a ball of casein.


I crumble the casein into a fine mesh strainer, and wash it under the tap for a few seconds until the water is clear to remove all the whey and any byproducts that may be in the milk.


Next, I dilute a 1/2 teaspoon of borax in 2 tablespoons of distilled water. This alkali will change the casein into a glue. I put the casein in a small jar, and stir in the borax liquid.


I stir the contents every 20 minutes or so, and after about four hours it turns into a thick gel. It’s still a little lumpy at this point, so I would want to let it sit for a few more hours before using it for anything. I added a drop of thymol as a preservative.


So, this brand of milk works well as a source for making casein glue as a binder for paint or gesso. The biggest drawback is that it’s pricey. It’s twice as expensive as the last jug of raw milk I bought, and three times the price of regular commercial milk. It would be better if I could get it in a smaller size, since this is way more milk than I need. Unfortunately, it’s only available in 1/2 gallon. I can also use it for food, of course. It tastes okay, a little more buttery than regular milk. I could make cheese from it, but would want to use something other than vinegar, perhaps lime juice.

Well, the lime juice worked. I substituted it for the vinegar, using half a lemon, and the casein separated from the whey easily. It took a few extra seconds, and more stirring, but the results were the same. I’m not certain, but the casein felt not quite as firm this time, however. I saved the whey and lime juice liquid, and added it to my pasta sauce for tonight’s dinner. I mixed some oregano into the casein (a.k.a. cheese) and crumbled it on top of the spaghetti. Tasted good.


Testing Kalona Brand Milk for Making Casein

March 26, 2016


I was recently introduced to a person who makes her own cheese, and in out conversation I mentioned that I like to use raw milk from a local dairy farm to extract my own casein to make a paint medium. She suggested a particular commercial brand of milk I could try that she uses for her cheese process. It was called “Grassmilk” from Organic Valley, and was carried by a local natural foods store where I live. I went by there this morning, but unfortunately, they didn’t have the fat-free version that I needed. However, there was another brand from Kalona that had all the same features.

The one small drawback to using this for making casein is they are required by law to add palm oil for the vitamin A. Raw milk suppliers don’t have to do that. The amount added is very small, however, and I think I can safely wash out most of it in the processing. They don’t add soy oil for vitamin E that other commercial brands do, and a bonus is that it is non-homogenized (“cream-top”) and vat pasteurized at low temperatures. Non-homogenized is important since it makes the casein easier to extract, and VAT pasteurized makes the casein firmer than the typical ultra-pasteurized process of most commercial brands. The Kalona is more expensive than the raw milk I was buying, but the store is closer and easier to get to. If you’d like to make your own casein, but don’t live close to a dairy farm that sells fresh cow’s milk, these brands may be a good alternatives for you.

Soon I’ll make up a batch of casein from this, and see how it works out.


Painting Final: Channel Surfing

March 6, 2016


I added a little more modeling to her front forearm, and made a few other small tweaks, so I’m going to call this one finished. (9 x 12 ” oil on drafting film)



The oil medium I used for this was a mixture of some oil (Winsor & Newton Refined Linseed) with a casein medium of my own making. Although the medium is quite fluid, I wouldn’t describe it as thin, since there’s no solvent used other than the water in the casein. This mixture usually dries fast, but on this drafting film surface it takes an extra day or two. The only brushes used were a #3 Round and #0 Round.



Art Material Review: Sinopia’s Casein Gesso

November 12, 2015


A few days ago I popped over to Sinopia’s website to see what’s new. They’ve long been highly regarded as an excellent supplier of raw pigment and paint making supplies. Among this is material for making casein paint and gesso grounds. Gesso, as you may know from some previous posts of mine, is a paint ground made traditionally with rabbit skin glue or casein, and different types of plaster solids. What was new to me is they now offer a casein based gesso that you can buy ready-made. No mixing of materials, just open the can and paint it on. I ordered a small jar of it that arrived this afternoon.

As I waited for the order to arrive, I fired off a few questions to Sinopia that they responded to quickly.
If I use this on paper, since it contains oil, should I first add sizing to the paper before applying the gesso?
“Even though the Gesso contains a linseed oil emulsion, it is completely water soluble and safe to use on paper without any sort of primer. The Casein Gesso makes a great substrate for oil painting.”

Does it have a shelf life?
“No, our Gesso does not have a shelf life. Although, once the container is opened and air gets into the jar, then the paint starts to skin over after a few weeks. In that case, the dried paint layer can simply be peeled off and the paint underneath is still in perfect shape.”

Should it only be used on firm supports? Can it be used on stretched canvas as well as wood panels?
“The Gesso works well on both panels and stretched canvas.”


Below are my first impressions of this product:
It is very thick, more so than I expected. Thicker than acrylic primers I have used, but about the same as oil primers. It can be brushed on right out of the jar, but you’ll need a good thick brush. However, it can certainly be thinned with water. If you thin it and use it as an oil paint surface, I would recommend sizing the surface first.


In the picture above I show on the left a thinned mixture (about 30% water) on a black sheet of mat board. On the right side of the board I painted 2 coats right out of the jar. I painted the 2nd coat (not thinned) after about 15 minutes, and it took about 30 minutes or so for that to dry to the touch. A hair drier can speed up the evaporation of the water content.


In this picture I’m comparing the 2 coats of gesso to Golden’s acrylic primer. The primer is much thinner, and 2 coats of it are not as bright as 2 coats of gesso. The gesso covers quite well, even on this dark black paper.


There was no information about how long to wait before I start painting on this surface. In my initial test, I waited 2 hours after applying the 2nd coat, and tested casein, oil, and gouache paint. I used the paint right out of the tube, and thinned with water or turpentine for the oil. I saw no problem with adhesion, or more importantly no reaction with the ground lifting into the paint. I even washed the surface with a brush loaded with water, dabbed it with a paper towel, and none of the white was released.

Other thoughts:
Regarding oils, it is recommended by Golden when using their acrylic primer that has been thinned with water, you should wait several days for all the water to evaporate before applying any oil paint to the primer surface. In this case, I would advise the same with the casein gesso, since there is some water already inside it.

In Sinopia’s description on the website they say this has “all the same qualities” of rabbit skin glue gesso. I would say it has some, but it doesn’t feel the same. I’ve made many gesso panels using RSG or casein (without using an oil emulsion,) and I can say that this surface feels different. Traditional gesso feels like a slab of cold stone. This reminds me more of an oil primed surface. It is a water and oil emulsion, after all. I like that feel, but it’s not like traditional gesso to me. The big difference with an oil primed surface and this, of course, is you can’t use any water media on top of an oil primer. Also, an oil primer takes a long time to cure, but this does not.

Comparing this to a traditional gesso ground, despite the different feel, this has many similarities and some benefits. RSG requires much more preparation time, and has to be held at a warm temperature while using. Once it’s made it has a shelf life of only a few days at the most. Casein gesso that I’ve made (not using emulsified oil) can last up to 4 to 6 months in refrigeration, and then starts to break down and become useless. According to Sinopia, this product can be stored indefinitely. No refrigeration is required. It’s equally as versatile as traditional gesso for use with all media, but according to Sinopia can be used on flexible surfaces like a stretched canvas, which is not true of traditional gesso.

The biggest problem I’ve had with acrylic primed surfaces is they destroy brushes. The solids in them will wear down an expensive brush in no time at all. Time will tell if this casein gesso will have the same problem. I suspect not. There are some acrylic primers that will work with watercolor or gouache, like Fredrix’s Watercolor Canvas, or Ampersand’s Aquabord, but the surface has to be made porous so they’re even rougher for brushes. Also, if you apply those primers yourself, like Golden’s Absorbent Ground, they are supposed to be applied on top of a standard acrylic ground, so you have to have both types. This casein gesso doesn’t have those problems. It appears to me at this point to be more versatile, potentially more so than any other ground on the market!

I’ve only had this for a day, so much more testing is required. My first impression is very positive.