Pastiglia – say what?

July 15, 2019

I’m currently involved in a project that calls for sixteen panels to be pre-textured before commencing to paint them. All of the paintings are to be executed on hardboard, so I’m starting with a firm, inflexible surface. Six of these panels will be painted with either oils or acrylics so I was able to use acrylic modeling paste for them. Here below are a few images of these already completed panels: source image on the left (duh), impasto-ed panel on the right.
This one serrendipitiously contains three figures (like a panel in a comic strip).

The second one is pure textured wall modeling.

But for the other ten panels I planned to be using egg tempera or encaustic so I needed to prepare their surface with traditional (white chalk and hide glue) gesso. And although I could apply acrylic modeling paste to the traditional gessoed surface, it would not be absorbent to the egg tempera or melted wax later on. So hmmmm… what to do?

I’ve seen, of course, that Medieval and/or Renaissance painters would sometimes pre-texture their grounds before painting on them but it took some diligent research to find out more about their technique. My two main resources were Cennini’s “The Craftsman’s Handbook” (translated by Daniel Thompson) and Thompson’s own “The Practice of Tempera Painting”. There I discovered a technique called “pastiglia” which appeared to be what I was looking for. Cennini briefly describes using gesso to model figures and ornaments upon an already gessoed panel (pg. 76). Thompson provides a little more detail (pg. 34-35). Both suggest using gesso and a brush to model low relief forms. In addition, Thompson suggested adding a little color to the gesso so you can actually see what you are doing (!!). Good idea, Daniel, I might take you up on that. But most of the information (and use) seemed to relate to decorative frame elements which was not exactly what I had in mind. No matter. I had found the term and now I could google it.

Strangely enough, there was not much out there in internet land. But there was a wikipedia page. I’m thinking this lack is due to the fact that pastiglia is not a technique practiced by many modern or contemporary painters. Most painters paint on flexible surfaces these days: the bigger the better. And they use acrylic gesso to prime their canvas. Which, while all of that is OK, it just means that these older techniques are not only out of vogue; their internet-memes are simply out of time. Luckily I was able to watch a three part you tube video of a guy making a frame using pastiglia. It was instructive methodologically and emboldened me to go ahead and just go for it. Two tips I received from the video, transfer your design beforehand and instead of using a brush, pick up a syringe or two of different sizes to better control the flow of the pastiglia over the gessoed panel. So I went to my local pharmacist and got myself supplied. Now I was ready to go.

Using the “find edges” feature of an image manipulation application I turned the colored photographs I had into black and white designs. I then printed them out to size and got ready to turn the printed image into “carbon-paper”. Note to self, never, ever, forget that photography renders the three dimensional phenomenal world into two, so “finding edges” is helpful but it cannot distinguish between a shape and a shadow. I had already used this carbon-paper technique for the acrylic panels, so I knew where I was going, but instead of covering the back side of the paper with charcoal, this time I chose yellow ochre pigment. The reason for this was simple, previously, the dark carbon lines were great for setting out the design on the acrylic panels but afterwards it required a few coats of acrylic gesso to reclaim the whiteness of the surface. I didn’t think that I would have that flexibility after the pastiglia treatment, so I opted to use a light tonality that would provide hints but also would not be too disruptive to the final painting. Here below some images of my yellow ochre transfers before modeling.

Now it was time to set to work. I don’t have images of the progress of all the modelings. Suffice it to say that it succeeds in layers so patience is required. I found it best to work up one area and let it dry (about 24 hours) before working on the area adjacent to it. Or sometimes, if there was a shape that was on top of another shape, I modeled the rear form first and then the second on top of it. Relative to my source image, if it was complex, I had to select the most important shapes and let the rest go. Here below are some completed pastiglias. The surface is far more delectable than the photos can suggest since it is basically white on white. Source image to the left, pastiglia to the right. Some draping fabric and tiles:

Men’s heads: