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dbclemons 11-11-15 02:41 PM

Casein Gesso from Sinopia
I happened to pop over Sinopia's website recently, and noticed they are now selling casein gesso. For many years they have offered the raw material for making casein and gesso yourself, but now they are also offering it pre-mixed, which came as quite a pleasant surprise. As some of you may know, it offers the same look and feel as gesso made from rabbit skin glue. The major difference is they claim this gesso has no limited shelf life, possibly due to the oil content.

I've been making my own casein paints and gesso for many years, so I was curious to see what their's looks like and ordered a small sample. As soon as I get it, I'll test it out and let you know what I think. If anyone here has already tried it, let me know.

Here's a link:

Salamander 12-11-15 01:57 AM

I'm interested to know what you determine. Thanks, Eric

dbclemons 13-11-15 01:18 PM

The jar of gesso arrived in the mail yesterday. I think I'm going to like it, but it's not quite what I expected. I hesitate to call this a "gesso." It's more like an oil primer to me, but an oil primer that you can paint on with water based media.

I wrote up a review of it on my blog last night that you can read here:

I didn't test egg tempera on it, or not yet anyway. Since I wouldn't refer to myself as a tempera painter, I wouldn't presume to advise such artists on how it feels. You should check it out for yourself. A 4 ounce jar was just $8. Gouache and casein paint work on it very well, so I expect egg tempera would also.

Salamander 13-11-15 03:38 PM

cool, thanks

Koo Schadler 15-11-15 08:34 PM

Thanks for the news about the casein gesso, DB. I just visited Sinopia's website, ordered a jar, and am eager to try it.

And now I’ll play the skeptic. If you want to skip the long, possibly tiresome essay that follows, here’s the gist of my post: if you’re new to egg tempera and want to best understand and make the most its potential, make a dozen paintings on traditional gesso (“TG” - an animal glue + chalk or gypsum ground). Next make some paintings on one or more of the TG substitutes (such as Sinopia’s casein gesso). Only then can you make an informed decision as to which ground works best for you.

That's the gist. Onto the long version.

I’ve tried several off-the-shelf grounds advertised as suitable for egg tempera (Clayboard, Art Boards, Golden's Absorbent Gesso) and I'm currently experimenting with another manufacturer's trial run at a ready-to-use gesso for tempera. Each has good qualities - fast and easy to use, brilliantly white, more absorbent than plain acrylic polymer gesso. But so far, in my experience, none works as well for tempera as TG.

Egg tempera loves an absorbent surface. An absorbent ground causes the water in the paint, which is the solvent for the paint, to be whisked away - this means that as a new layer of paint is applied, it is less likely to dissolve and lift the underlying paint layers. Most tempera painters agree that layering is at the heart of egg tempera, and it's hard to layer when each new stroke too readily lifts the paint underneath.

What makes traditional gesso (TG) unique is that it is composed of just two substances, both of which draw water: animal glue and either chalk or gypsum - nothing else. (This can make TG problematic in the long term; it can attract moisture which may affect a painting's durability - but that issue can be mitigated, all grounds have pros/cons, and durability is another topic altogether).

The recurring limitation of TG substitutes is that they contain one or more substances hydrophobic to water. Rather than attract water, these ingredients repel it. In the case of Sinopia's casein gesso, among other things it contains oil (hydrophobic) and a natural resin (all resins, as far as I know, are derived from essential oils). Sinopia's gesso also contains water-attracting substances like calcium carbonate (chalk) and seashells, so I don't mean to say their gesso lacks absorbency - no doubt it is absorbent. But as long as a gesso substitute contains ingredients that repel water, can it ever equal the absorbency of TG, which contains nothing but water-loving substances?

Whether this matters depends on the painter and his or her goals. Undoubtedly egg tempera can be applied on Sinopia (and other) gesso substitutes and will adhere in both short and long term. (Whether it adheres as well in the long-term is less certain). What egg tempera won't do, in my experience, is behave the same on top of TG substitutes. The paint's working properties change; the paint more readily slips and lifts (sometimes ever so slightly but enough, perhaps, to matter), which makes it more challenging to accumulate layers (and layering, as mentioned, is central to most tempera painting).

If a painter tries both TG and a gesso substitute and finds what they’re looking for in the substitute, then by all means, use the timesaving substitute. It’s a practical, informed choice. What interests me (and why I indulge in this possibly/probably tedious harangue) is what happens when a newcomer sees a TG substitute advertised as “ideally suited for…egg tempera” (Sinopia), or “the perfect ground…for egg tempera” (Art Boards) and tries tempera for the first time on one of those grounds. It’s not that the paint won’t go on – it will – but it won’t behave the same. A beginner won’t know this, and hence won’t attribute ill behaving paint to a less fully absorbent ground but instead might think such problems are inherent to the paint or painter - and, sigh, egg tempera’s reputation as an impossibly difficult medium is affirmed, and/or uncertain beginners are unduly discouraged.

Clayboard has a page on their website to explain why their product is well-suited to egg tempera: http://ampersandartsupply.blogspot.c...out-using.html

Some of their points are well made (clayboard probably does adhere better to a support than TG – although the numerous well preserved Renaissance paintings, all of which were made with TG, indicate that TG probably adheres well enough), and I agree with Clayboard that good tempera paintings can be made on its panels (I know some of the satisfied customers Clayboard mentions and their satisfaction is genuine). Again, I take no issue with experienced painters who have tried various grounds, including traditional gesso, and ultimately found success with clayboard. Rather, it’s the newcomers to the medium I wonder (worry) about. Clayboard says:

“We have received only a couple of calls over the years about lifting, but in talking further to the concerned artists and other egg tempera painters, we have found that individual technique is most likely the cause, not the painting surface.”

The company then details a specific working method to deter lifting on a clayboard panel. That clayboard necessitates these steps seems to support my assertion that it does not have the same working properties of traditional gesso. After all, my “individual technique” works very well on traditional gesso; it is problematic only on clayboard! It seems unfortunately limiting to beginners to be told there is a rigid, proscribed method one must follow to succeed in egg tempera painting, when in fact that method is requisite only when egg tempera is applied to clayboard.

I know an ET painter with decades of experience, work in museum collections, who for many years worked on clayboard. I said, “Try traditional gesso”. He switched and for several years afterward, when asked, said he wasn’t sure he felt a difference between the two grounds. This summer, in a pinch, he did a painting on Clayboard for the first time in many years. He told me he didn’t know how he had ever worked on Clayboard, that traditional gesso is much better, there is no going back. I don’t dispute that he’d previously produced beautiful paintings on Clayboard. My point is only that, in my experience, most people feel TG has noticeably better working properties than any other ground, which is important for beginners to know.

(I could also discuss the challenge of sanding many of these substitute grounds to the ivory smooth perfection that, while not requisite, is important to many tempera painters and easily obtained with TG, but already I’ve gone on too long…)

If I seem to be beating up on Clayboard, Sinopia or other companies that produce gesso substitutes, it’s not my intent. (I've ordered Sinopia's gorgeous pigments for many years and esteem their business). Egg tempera is not a commercially viable medium for the most part: pure ET paint can't be prepackaged in a tube; a well-crafted TG panel is labor intensive and expensive to make; tempera customers are few and far between. Given the minimal financial rewards it’s a wonder that any manufacturer dips their oar into the waters of egg tempera.

So, on the one hand, I appreciate companies such as Sinopia and Clayboard that produce easy to use tempera products such as off-the-shelf gesso. They save time, suit some artists, and there is a place for them. On the other hand, I’m disappointed that these products are described as equal to traditional materials and methods; they’re not. Yet it would be impractical, of course, for a company to say “the absorbency of traditional gesso is requisite for most working methods in egg tempera and is not matched by our product; however there will be some artists and methods for which our product is well suited”. I realize this is unrealistic. Full disclosure might doom the product, but lack of full disclosure is misleading. It’s a conundrum, and I'm sympathetic. As a small contribution toward resolving it, I’m willing to appear as a troublesome pest by continually reiterating what I believe is the meaningful difference between TG and the gesso substitutes I've tried so far.

I’m not adverse to changes in the egg tempera tradition (after all, I paint with makeup sponges and am trying aluminum panels, among other things) and hope I don’t come across as a closed-minded, stuck-in-the-Renaissance-mud windbag. My intention is to encourage what are, I believe (from my own experience, the overwhelming majority of full-time tempera painters I know, and hundreds of students) the materials and practices most likely to bring about success in egg tempera, because I think egg tempera deserves to succeed.

It also seems necessary to say in the ongoing conversation about easy-to-use materials for egg tempera that, compared with other mediums, tempera generally requires a bit more hands-on labor. For most tempera artists that work is sometimes challenging but mostly enjoyable and fulfilling (and in part why they love the medium). There’s nothing wrong with instant art supplies (there are many good things about them) and I’m not opposed to speeding up the painting process (as long as an expediency doesn’t compromise the work). But there’s also a place for a type of painting that takes knowledge, time, patience, effort.

This ramble is not meant to negate DB’s posting about casein gesso. Thank you, DB, for buying, trying and mentioning it. I'm eager to try it myself (and if it works beautifully I'll eat my humble pie and tell you). I mean only to say that "if you’re new to egg tempera and want to best understand and make the most its potential…" (refer to beginning of this post for rest of statement…)

Anyone who has gotten this far, thanks for listening. Comments, corrections and critiques are welcome.


dbclemons 20-11-15 03:03 PM

You make valid points, Koo. It's why I started this post with a caveat that I expect e.t. users to make their own evaluation. I certainly understand how artists can love their materials. This would fall into a "don't fix it if it isn't broke."

I wouldn't refer to this product as a "substitute." I think "alternative" says it better. For anyone who would want to use an alternative primer, such as Golden's Absorbent Ground, to make their own surface rather than buy a ready-made panel, I believe this product holds more promise.

A quick test I made on this with my own egg tempera paint showed that it works fine. I was able to paint layers without seeing any lifting. I invite more experienced e.t. painters to give this a thorough workout.

I hadn't bothered to sand the last coat of the primer, so there were brush strokes from it showing through the e.t. layers. I would recommend adding 1 or 2 extra thinner coats of primer on top of the first 2, and/or sanding it to get a smoother surface. It does sand rather easily, unlike acrylic primers I've used.

I'm anxious to hear what you think of this, Koo.

Koo Schadler 21-11-15 01:12 PM

Sinopia's gesso arrived yesterday. Good idea about layering thinner coats of primer on top. I'll give it a try today and I'll let you know how it works for me.


Koo Schadler 29-11-15 04:27 PM

Testing on Sinopia's Casein Gesso
Hello All

I’ve done several tests on the Sinopia Casein Gesso. The best way to understand the ground would be to do some fully developed paintings on it, but I don’t have time. Still, I believe the experiments I did were informative.

It’s a bit long explaining tests and results, so I’ll cut to the chase: Sinopia’s Casein Gesso may suit some working methods but it does not behave like traditional gesso. I’ll describe in depth why I think so, and if anyone wants to see photos of my results I’d be happy to email them.

As DB mentions in his review, the consistency is a surprise: Very dense, akin to Elmer’s glue. I used a trowel to even the surface (brush left too many marks). The gesso was hard to get even but self-leveling to a degree. Two coats achieved opacity. It needed overnight to fully dry. It sanded well with a light touch, but any pressure with the sanding block (to address irregularities in the surface) created pil ls and tearing/lifting in the gesso. I made a second panel, thinning the gesso considerably with water and applying 6 thin coats – this created a less dense surface, seemed to dry and sand better.

A smooth ground in egg tempera is often desired for two reasons: First, if there is gilding on the panel the surface must be smooth to emulate metal. Second, tempera is a very thin paint and underlying textures readily telegraph through, so if you don’t want gesso irregularities to show in the paint layers you start with an even ground. In short, a gesso’s capacity to be made perfectly smooth is important to many tempera artists. On a scale of 1 to 10, in terms of ability and ease off being smoothed, I give Sinopia’s Casein Gesso a 6 (traditional gesso a 10).

The Casein Gesso is off-white, yellow tint. This doesn’t matter to me but some tempera artists feel prefer a pure white ground.

I did five identical tests (same quality of paint, drying time, etc.) on Traditional Chalk and Glue Gesso (TG) and Sinopia Casein Gesso (SCG).

Test 1: Built alternating strokes of 5 different colors using thinned tempera paint applied with a well-wiped brush. This is perhaps the most common way to work in tempera. As soon as first strokes were dry to the touch I applied another layer of brushstrokes, etc. I used the same drying times on the SCG panel as on the TG panel.

Results: The TG allowed subsequent paint layers to be applied fairly quickly (within 5 to 10 seconds). Each layer stayed distinct, without lifting or blending with underlying paint layers.

Using the same drying time on SCG, the underlying brushstrokes were re-dissolved by the application of new brush strokes. By the time I got to layer five, paint had lifted and the colors were muddied.

When I tripled drying time between layers on the SCG, the brushstrokes stayed more distinct; but eventually water accumulated within the ground, drying times became longer, and by the tenth layer lifting and muddying reoccurred.

TEST 2. I used sponges to apply layers of thicker paint, much less water content. As each layer dried I polished the surface with cheesecloth to see if paint would lift and if I could pull out a shine.

RESULT: Both the TG and SCG panels took thick paint well. When there is less water in the paint, the SCG ground behaves well.

Later, as I worked on other parts of the SCG panel, a section of sponged paint lifted (not sure what I did, perhaps brushed it with my sleeve). It was a bit more vulnerable (in the short term) compared to sponged paint on the TG panel, but a few days later seemed to be adhering well.

TEST 3. On top of several layers of dry paint I applied a very watery glaze of yellow ocher, known as a “petit lac” (a little lake), a common icon painting technique. When the petit lac felt dry to the touch on the TG surface (after a few minutes) I pressed a paper towel over the surface to see if any water content remained and if lifting would occur. I replicated the test (same drying time) on the SCG panel.

RESULT: On the TG panel there was no lifting of either the petit lac yellow glaze or underlying paint layers. On the SCG panel the paint lifted, and a bit of gesso too.

TEST 4: Put a drop of water on top of thick, sponged on paint: another drop on top of strokes of thinly applied paint. I wanted to see how quickly surfaces absorb and react to water. I dipped a paper towel corner into each water drop, without letting the towel actually touch the panel, to lift out excess water. Next I let the surface dry to the touch, then polished it. Finally, I used a sharp stylus to incise a circle around each water drop, both to show where it had been and to see how receptive the gesso is to a stylus (a common tempera technique is to incise into ground to delineate an image).

RESULTS: On the TG ground, when I dipped the paper towel into the drop, only water was drawn up (no pigment; the paint stayed put). Once dry and the surface polished, no evidence of either water drop remained (paint was undisturbed). The stylus incised crisply into paint and gesso.

On the SCG ground the drops of water visibly swelled the gesso, creating a raised bump in surface. A paper towel in the drop not only sucked up water but bits of color too (paint was disturbed). When surface was dry to the touch and polished, paint completely lifted where water drop had been (there was still moisture within the ground). A stylus on the surface was like incising into mud; tip dug deeply into and tore the gesso. An hour later a bit better but still a bit mud-like when incised.

TEST 5: Silverpoint drawn on the surface.
RESULTS: TG receptive to silverpoint: made sharp, clear lines: varying pressure could be applied to vary line. SCG was very receptive to silverpoint applied with a light touch (made a rich grey line), but if pressure applied the stylus dug into ground. The lines were not quite as sharp, and if rubbed would smear and lift.

The main takeaway for me is this: the SCG ground is absorbent (tho’ it does not suck up water quite as quickly as TG). More significantly, the SCG ground holds onto (seems to store) water for a long time, which leads to lifting and other problems. TG is much better at whisking water away, allowing for subsequent layers to be applied quickly, cleanly, distinctly.

SCG’s working properties undoubtedly would improve if I significantly increased the drying time between layers (which is what Clayboard recommends for their ground). However this slows down and fundamentally changes many common working methods in egg tempera, and makes it harder, slower to build the innumerable layers of color that make tempera unique and luminous. Even with longer drying times, I believe (given my experience working on other TG alternatives) that water eventually accumulates in the ground and might still lead to problems.

I don’t mean to speak against the ground in general, only to clarify how it responds to tempera. My apologies to Sinopia, I’m sure they’ve done testing and believe it to work well - and it probably does for some approaches (looser styles with few layers, people who can afford to wait a long time between layers). But I can’t agree that SCG “offers all the attributes of a traditional chalk ground” or that it’s “ideal” for most tempera artists. If I sound impossibly picky, I've experimented on two other alternative grounds being developed by another manufacturer, and one shows promise. I’m neither permanently wedded to traditional gesso nor opposed to faster alternatives – I just want a ground that allows people to make the most of the medium.

If traditional materials are replaced (for the sake of convenience) by alternatives that don't allow for egg tempera's unique characteristics, then we will lose much of what makes egg tempera special.


dbclemons 03-12-15 09:36 PM

This is great, Koo. Thank you for your thorough testing. It was enlightening.

This ground should work well for other applications that don't need a great deal of water, especially oils or perhaps a tempera grassa.

Koo Schadler 11-12-15 03:12 AM

Thanks for raising the topic of alternative grounds for ET - its an important subject and worth looking into. Although not suited to me or most tempera artists I know, Sinopia's casein ground is interesting and most likely has potential for some mediums and methods - if anyone else experiments with it, let us know!


arbrador 24-12-15 06:09 PM

More on casein gesso
Hi All~
Many years ago I tried casein gesso because I liked the idea of not having to use warm gesso and wrestling with air bubbles. I can't remember why I did not pursue it but remember that I did not like the surface as much as traditional gesso.

Recently Elaine Drew tried the Sinopia version and also was not happy. Here is her summary:

"Mostly, it seems the paint doesn't adhere well to the surface. I did a couple of pieces that came out all right, eventually, but the paint sliding off was annoying. After enough layers were built up it seemed to be better. I also had a problem doing an ink underpainting; that slid off as well."

She did extensive experiments at the time including using traditional gesso over a couple of coats of casein gesso but in the end abandoned the whole idea of using casein gesso.

At least now we can buy our smaller panels at a reasonable price. My problem it I'm painting larger and larger ETs and there's no way I can afford to buy a gesso panel that is, for example, 4'x8'. So back to the meditation of traditional gesso.

Koo Schadler 25-12-15 03:58 PM

Thanks for describing Elaine Drew's experience, Lora. At the risk of redundancy, but for the sake of ET newcomers, I'll point out that Elaine is an accomplished tempera painter who, from past experience, was able to recognize the distinction between the working properties of traditional gesso and casein gesso. A newcomer to the medium wouldn't know that the casein gesso wasn't behaving optimally for egg tempera, and might assume that slipping paint is intrinsic to tempera (or the fault of the painter). That is the problem with new grounds that are advertised as ideal for tempera - they mislead the beginner. Which is why, much as I like Sinopia as a company and think their products are generally great, I'm being a bit of a pest here regarding casein gesso; my persistence come from advocacy for egg tempera.

No doubt, making gesso from scratch is work, particularly a large panel. To clarify (again, primarily for beginner's sake) there are ways to mitigate and/or eliminate air bubbles: minimize agitating the gesso while making it, let prepared gesso sit in the fridge for a day or two (so it can settle down) before application, add a flow aid to the gesso, don't overheat the gesso (keep it just warm enough to stay liquid), don't have too much of a temperature difference between the panel and gesso, be attentive as you build layers, etc...

Whatever the work involved, keep in mind the benefits: As Lora points out, it is a thoughtful, meditative process. It makes you more knowledgeable of your materials and process (which, if not certainly, can potentially make you a more attentive, better painter). These are increasingly less common but perhaps worthwhile experiences. Understandably, they are not for everyone - but we tempera-philes already knew that about our medium!

I admire you following a call to paint large, Lora - I'm working on a 14 x 18" triptych and it feels like my limit (well, at least for now, maybe forever). The Death of Jack Walsh on your website is a beautiful painting. Congratulations on persisting in the challenges of a medium I know you love.


dbclemons 01-01-16 03:19 PM

I want to be sure everyone's aware that there is a distinction to be made for the term "Casein gesso." You can make it using casein as a substitute for rabbit skin glue in the traditional manner. Sinopia sells all the raw materials to make it that way. They also sell this casein gesso product which is NOT the same thing. It is an oil primer that uses casein as an emulsion. I've been making true casein gesso for many years, and prefer it over RSG, mostly for the sake of convenience, but also for the results I get.

Koo Schadler 06-01-16 01:40 PM

Excellent point, DB - thanks for clarifying.


Koo Schadler 15-11-17 06:59 PM

Hello All,

As discussed in this thread, several years ago Sinopia (an art supply company in San Francisco) developed two new grounds advertised as suitable for egg tempera: casein gesso and chalk casein gesso. Both products have the convenience of being pre-made, ready to apply. I tested the chalk casein gesso and, for me, it didn't behave well; paint lifted, it was hard to quickly accumulate layers without lifting, very watery applications of paint took a long time to dry. I wrote about it in this post and recommended against Sinopia's chalk casein gesso for egg tempera.

Leslie Watts, a well known egg tempera painter, recently tried both of Sinopia's casein grounds and found them to behave well. She wrote about them in a blog post. Everyone has different working methods, and what may not suit one painter may work perfectly well for another, so it seemed only fair to offer a differing opinion on these grounds. A link to Watt's post is below.

Koo Schadler

dbclemons 21-11-17 04:32 PM

Thanks for the link, Koo. I appreciate hearing about your experiences with their two grounds. It's worth mentioning that both of these Sinopia grounds are made with the same binder using casein with oil and resin. The chalk ground includes extra pigments titanium and zinc.

On your point about different working methods, can you add more detail on what methods could be leading to these different results? Have you worked on grounds with any oil content before? I'm wondering if that may be what's causing you difficulty.

Koo Schadler 25-11-17 07:54 PM

Hi DB,

I have worked on oil based grounds, but only when painting in oil. There seems to me a fundamental incompatibility between a ground that contains (even a very small amount) of oil, which is water-phobic; and a water-based medium, such as egg tempera - especially if controlling and getting the water in ET paint off the surface asap (by having it be absorbed by the ground) helps in controlling the paint.

If a tempera painter has a working method that uses absolutely minimal water - i.e. very dry brush - than that painter probably can get an oil-based ground to behave. I work a lot with dry brush in egg tempera, but I also work with puddles of paint, thick sponged-on layers, wet splatterings, and other water-intensive ways. Additionally I accumulate a lot of layers, anywhere from 20 to 200, often quickly, depending on what I'm painting (and the more layers, no matter how they're applied, the more water is introduced into the ground).

Another consideration is brushwork. Crosshatching (how many ET painters work) helps weave together the paint; and a single, thin brushstroke is less likely to lift or affect areas of previously applied paint. I don't do a lot of crosshatching. I apply more random mark-making, as well as continuous layers of paint. Continuous paint layers are less interwoven, and their application is more likely to wet and thus affect larger areas of a painting, which potentially creates more opportunities for lifting (if the water has no place to go).

All these things are probably why my working method is not well suited to a ground with oil in it. Egg tempera (unlike oil) can't be physically pushed around or blended on the surface; instead ET painters create an image by (a) controlling the sort of marks being made, and (b) accumulating layers. These two things are possible only if a painter has control of the water content in the paint, and a maximally absorbent ground helps to do this.

If you have any thoughts on the above, I'd be most interested. Also, if you've had experience with any of the alternative gessos, please share. It's good to hear your voice on the forum.


dbclemons 02-12-17 03:59 PM

Thanks, Koo. I appreciate the information.

I made some simple tests with e.t, casein, oil, and gouache paints on this, and they all seemed to adhere well, but haven't yet tried anything advanced with them on this surface. Honestly, I tend to avoid using a primer unless I'm painting with oils, which I haven't used in awhile.

As I mentioned in my own review of this, I wouldn't describe this as a gesso. It's an oil primer with a casein emulsion that makes it water-miscible. It makes sense that if you use a paint on it that is heavy with water, that can be problematic. If anything that is touted as being more convenient to use forces you to have to alter your preferred method of working, then it isn't really worth using, in my opinion. I still have a little bit left in the jar, so I may get around to doing more work with it later.

One last observation I made: it comes in a plastic jar with a screw-on lid. One big reason I dislike using jars (glass or plastic) of this sort to store mediums is they tend to let air leak in. This jar was no different. When I opened it recently I found about a third of the contents at the top had dried solid, even though the lid was screwed on tight. If anyone buys some of this, be sure and use it up quickly.

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