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Chris 16-11-17 02:31 AM

Gesso problems
I've been learning about and practicing egg tempera for a little more than a year. I have a background in antique restoration and really enjoy the "craft" of egg tempera. Ive also always done detailed and rather elaborate ink drawings. So, the linear quality and opportunity for subtlety in egg tempera made it seem like the perfect medium for me. The area I'm trying to improve in right now is color. Trying to "arrive" at the right color after several layers. And also, keeping that delicate look of the first few initial layers after many layers. I somewhat ruined a painting of flowers by trying to get the right color. The petals after one or two layers were delicate and soft. After a few more layers, in an attempt to get the right color, they looked stiff and artificial.
So, my main reason for posting is a problem I had after making my own gessoed panel. I used gamblin gesso to gesso my panel and was careful to keep the temperature low. It looked really good after 6 coats. After a few days of drying, I decided to use a cabinet scraper instead of sandpaper, like I had done in the past, to level the surface. When I was done it looked great but maybe it was slightly shinier than normal. Then I tried to perfect it a bit more with my slightly damp fingers. It had a definite shine to it after that and almost looks a little yellow. I tried painting on it, but its too slick.
So, was it the scraper, the polishing with my fingers, a bad batch of gesso or maybe a combination? I really liked the way it came out after the cabinet scraper, so I'm hoping its not that. Maybe a different recipe of gesso would be more receptive to being scraped?
Thanks for any insight into my dilemna.


RobM 24-11-17 07:56 AM

Chris, I have no experience of Gamlin gesso as I make my own to a well tested recipe in the technical info section of this site....
Hopefully this post will give a bump and our gesso experts will come along.

Koo Schadler 25-11-17 07:12 PM

Hi Chris,

I can think of three possibilities why your gesso surface misbehaved:

1. One factor in traditional gesso’s absorbency is the amount of glue in the recipe. A typical gesso recipe is:

1 part glue +16 parts water +1.5 parts whiting (chalk or gypsum).

This yields a not-too-hard, not-too-soft ground. More glue in the recipe creates a harder, less absorbent gesso; more chalk (or gypsum) in the recipe yields a softer, more absorbent gesso. Gamblin’s products are generally very good, so I don’t doubt the quality of the ingredients – but perhaps their mix produces a hard gesso? I don't know. You could ask Gamblin if they’ll share their gesso ratios with you, to determine where it falls on the hard/less absorbent versus soft/more absorbent spectrum. Or, try adding a bit more chalk or gypsum to their mix and see what kind of surface results.

2. There are two ways egg tempera adheres to traditional gesso. One is via “dispersive adhesion”; molecular changes cause two disparate substances (egg tempera and gesso) to adhere. Dispersive adhesion is hard to explain; I don’t really understand it, I don’t think you need to understand it per se, but if interested you can look it up – suffice to say it is considered the most important kind of adhesion.

There is a second kind of adhesion that I think is also very important for egg tempera: mechanical adhesion. Think of Velcro or sewing…basically two disparate materials interlock or mesh with one another. Both egg tempera paint and traditional gesso have a very high “Pigment Volume Concentrate”, or PVC (see this link for more about PVC: The irregular surface (on a microscopic level) created by a high PVC ground and paint allows for the two substances to interlock or “knit” together.

Mechanical adhesion not only improves the long-term adherence of paint to gesso, it also helps the paint to behave as it’s applied. A ground with a bit of tooth (even if that tooth is imperceptible) lets the paint sink in and lock into the ground (and thus not be as prone to lifting with subsequent layers of paint). The porosity of a more open ground also allows water to sink in more readily, and this too makes it easier to manipulate the paint and build layers (since water accumulating on the surface can cause ET paint to continually dissolve and lift).

When you scraped your surface smooth with a cabinet scraper, you removed ALL the surface irregularity in the gesso. The shine you pulled out proves this: your gesso surface started as the equivalent of frosted glass (matte) and you smoothed it out to the equivalent of polished glass (high gloss). Thus no mechanical adhesion could take place, which made the paint misbehave and not adhere well.

I know one often reads that you should polish traditional gesso to the smoothness of ivory, and it’s true that traditional ET painters did so – but primarily this was for gilded areas: to emulate the appearance of solid gold, underlying layers must be perfectly smooth. But in areas that are not going to be gilded, there is no need to create a high level of gloss. Use sand papers of increasing grits (I start with 180 grit and end with about 400) ‘til you don’t see any more brush marks (or whatever tool you used to apply gesso), and until all you see are the barely visible scratch marks of 400 grit sandpaper. Then finish with a light water sanding (I prefer to use my fingers). That should be enough to create a beautifully smooth surface - but not a polished one with a high gloss that’s unreceptive to paint.

3. The final question I have is about the slight yellowing you saw after you rubbed the surface with water. I can think of two things that might cause that: (1) SID, or “support induced discoloration”, when water traveling in and out of the gesso causes impurities in the wood-based support to migrate up to the surface; and (2) as you wetted and rubbed the surface you lifted up chalk, the animal glue within the gesso migrated to the surface, which affected the glue to chalk ratio (and made a harder gesso). Both of these scenarios would occur only with a lot of water moving in and out of the gesso, which it doesn’t sound like you did - so I don’t think they are likely. I’m just trying to puzzle out that bit of yellow…

Hope that helps.


Koo Schadler 25-11-17 07:13 PM

Me again.

Well, if that previous post wasn't enough for you, I have more thoughts regarding your dilemma of trying to arrive at the right color and ending with a “stiff” look. Without seeing the image I’m not sure what you mean, but I’ll hazard a guess (and you can tell me if any part of my guess is relevant).

Getting a “stiff” look in egg tempera speaks to the pro and cons of the medium. Egg tempera is a very thin medium, and to bring ET out of the realm of watercolor requires the application of MANY, MANY layers. (Nothing against watercolor, but if painting in ET why paint like WC?) While there is the challenge in ET of not lifting underlying paint, this can be addressed – and so an adept tempera painter can accumulate nearly countless, distinct paint layers (unlike watercolor, which is always resoluble, so layers don’t stay distinct). But by the time enough of these MANY thin layers of ET paint accumulate to arrive at the desired quality of paint, an image can end up looking either over painted and sloppy, or as if the same line’s been drawn one too many times with a sharpie marker.

Does any of that resonate with what occurred in your painting? If so, here are two things that may help.

1) First, once you have an image more or less established try working with increasing thinned paint. If you build every layer with the same quality of somewhat "dense" paint (tho’ nothing is very dense in ET; it’s all relative) you may end up stating an object too emphatically, and/or more or less cover the underlying layers – in short, you either “over draw” with the brush or kill the atmosphere that comes from innumerable whisper thin layers. This is very hard to explain in words… suffice to say that if you are new to egg tempera, and think you are working with thinned paint, try thinning it TWICE as much, then modify your image with a few layers of this super thin paint - see if enough of these very thin layers add up to something visually significant, but in such a subtle way that you develop atmosphere and don’t overstate contours.

To reiterate: The quality perhaps most underappreciated by newcomers to egg tempera is how incomparably thin and inconsequential the paint can be at times, yet still those seemingly whisper thin layers contribute toward the development of an image (if enough such thin layers are applied - it takes patience....).

(By the way – once you have the proper ratio of egg to pigment, thin paint by adding water. Don’t thin paint by adding more yolk; too much egg just makes gummy, tacky paint.)

2) Another way to keep an image looking fresh (versus stiff) and atmospheric is to periodically apply whisper thin layers of transparent white (known as scumbles) on top. Think of it like laying on a fine mist, or nearly transparent layer of white cellophane on portions (or all) of a painting. A scumble will condense values (allowing a painter to better organize them), raise values (which means you may have to reinstate darks, but that's okay - this adds more layers and atmosphere to darks), impart a bit of opacity (which creates a great base for subsequent thin glazes of color), soften edges – it contributes all sorts of beneficial visuals that can counter a hard, stiff look.

There is much more I could say about scumbles – they are one of my favorite tools in the egg tempera toolbox – but I’ve already gone on too long. If you have any questions I’m happy to respond….or not say another word, I promise.

Good luck,

Koo Schadler

Chris 26-11-17 10:41 PM

Rob and Koo,

Thanks so much for your replies! I think your paintings are beautiful, so to have such experienced painters help me with my dilemma is awesome!

Since reading your post Koo, I sanded a bit of the panel in question with 400 sandpaper and painted on it. The paint did respond much better than it did before. The marks seemed to hold and not lift too easily. I understand the principles of mechanical bonding but always thought of it as something you need for a thicker paint or finish that would soak into the sanding marks and lock onto the substrate better. It does make sense that it would make the gesso more porous and absorbant also. So lesson learned.

As far as the slightly yellowed tone of the panel. There was one other thing i did differently than normal. Instead of using an Ampersand hardboard panel, I used some leftover MDF from Home Depot. When compared to another gessoed Ampersand panel, the HD panel (with about the same number of coats) looks yellowish. Whether this is from SID or from that last bit of wet polishing that redistributed the RSG, I dont know. It was so hard an shiny that I could barely get a pencil to take on it.

It seems like ill be moving in the direction of making my own gesso, starting with a basic recipe like you guys have suggested. I do have one other question that's along the same lines though. Having read a bunch of books on tempera and gesso, what's thw difference between Cennino's slaked plaster of paris recipe and the modern RSG + whiting recioe for gesso? Is there some bonding or chemical advantage to using slaked plaster or does it just act as a whiting. Again, Im just curious and will probably be spending my time improving my painting rather than slaking plaster.

The other thing I brought up was the layering of colors. If i had to guess what I did wrong, i may have painted too thickly or with too much white in my scumbles. I suppose next time ill experiment with the layering of colors on a scrap panel so I can concentrate on my handling instead of forcing the color through.

Thanks again,

RobM 01-12-17 06:03 PM


Originally Posted by Chris (Post 6906)
The other thing I brought up was the layering of colors. If i had to guess what I did wrong, i may have painted too thickly or with too much white in my scumbles. I suppose next time ill experiment with the layering of colors on a scrap panel so I can concentrate on my handling instead of forcing the color through.

Thanks again,

There is nothing wrong with painting too thickly or using scumbles, others may disagree. A very good friend of mine, Ceri Auckland Davies (Google him) paints almost impasto with tempera and to date his paintings have survived. I was slightly alarmed when I first met him and saw his works some 17 years ago. (He is also a very good cook when I last visited him a year ago....!) Having said that, I would advise learning the basics and then building on your experiences of failures and triumphs......that is how I developed the way I paint........white scumbles and glazes, using a toothbrush to splatter paint, there is no end to innovation but the basics need to be adhered to.....if that makes sense.....

Koo Schadler 01-01-18 04:13 PM

Hi Chris,

Excuse the tardy reply – you’ve probably been working away and have already figured out the answers to your questions!

Paints are essentially composed of three ingredients: binder, pigment (or filler), and vehicle (or solvent). A simple, not inaccurate way to think of traditional gesso is that it’s essentially a very high PVC paint. High PVC (pigment volume concentrate) means paint with a high ratio of “pigment” (in the case of gesso, an inert white filler) to binder (in the case of gesso, animal glue). High PVC paints make porous, absorbent surfaces. This is ideal for a tempera ground because (a) it allows the paint to mechanically bond and thus adhere, and (b) allows the painter to control the water content in the paint (the absorbent gesso underneath acts like a sort of sponge).

The “pigment” or filler in gesso should be:

1. Inert (i.e. you don’t want a chemical reaction to take place when water is added, such as when water is added to lime)

2. White and opaque (to increase the reflectivity of the ground so light bounces off, is not absorbed by it)

3. A proper crystalline structure to produce a hard, durable surface (versus, for example, talc, which makes too soft a surface.)

There are many chalks (calcium carbonate) and gypsums (calcium sulfate) that meet the above criteria. My preference is marble dust because I like the quality of surface it produces (but I suspect also because of the name itself: how seductive to paint on top of marble!) Other artists prefer gilder’s whiting, French Chalk, whatever you like best. I can’t think of a reason to make your own whiting.

Regarding thick paint: In my first reply to you I didn’t mean to imply that you can’t paint thickly in tempera. I was trying to address one reason why your flower petals may have come out looking “stiff and artificial”. As Rob notes, you certainly may apply tempera densely– in fact, I always start my paintings with thick paint (heavy cream consistency, which is about the thickest possible in tempera), then transition to increasingly thin paint on top of that, reverting to thick paint at the end for highlights (I don’t intend that as a description of how one should work in tempera, merely explaining my working method). As Rob says, the most important thing is to experiment, play, and build on your experience. Paint often, with attention, curiosity, and a wee bit of fearlessness.

There is a limit to how thick tempera paint can be applied without risk of cracking. I’ve let tempered paint sit on the palette to thicken to about the consistency of tubed oil paint, then tried applying this thickened tempera to test panels in impasto strokes, and hairline cracks appeared upon drying. I'm curious, Rob, how thick would you say your friend’s paint is? I’m always interested in people pushing the limits of ET. Please go visit him, so you can get a good meal at the same time.

Happy New Year to all,


Chris 27-01-18 03:39 PM

Thanks for the encouragement Koo! Yes, I have been painting away, making mistakes, trying to fix them and in general gaining experience. Im working on a variety of subject matter to try to broaden the possible challenges also which I think has helped.
I've also been gessoing away; using RSG and marble dust. All of my panels have come out nice so far (although I have to admit the Gamblin stuff looks a bit smoother and whiter. I guess that doesn't really matter though since it'll be covered up anyway).
Lastly, part of my reason for asking about "old school " or traditional gessoing techniques was out of an interest in Carlo Crivelli. After seeing a few of his paintings at the Met, I bought a book on him and was amazed at some of his surfaces where the gesso is carved or applied in relief in a few areas. The level of craftsmanship and care that went into these paintings is just astonishing.

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