Purity Complex

Pastels are, without contest, the purest medium you can use. Although pastel may technically be considered a drawing medium, it’s often referred to as a painting medium because of how generous and workable the soft, chalky marks are. I say “pure” because of how minimally the binder visually shapes the pigments. When you look at an oil painting, the luscious oil has just as much presence as the pigment itself. Pastels don’t operate in this fashion. The pastel binder has very little presence, only asserting itself enough to hold the pigments into the shape of a stick and to loosely adhere them to the surface. Essentially, the pigments are able to operate chemically and optically with very little influence from the binder itself. Now, I don’t say “pure” as a qualitatively good thing or a bad thing– don't be wooed by the notion of purity as idealistic. For my work, the physical presence of the binder and its countless possibilities for manipulation is pretty essential, as we've been over before. I personally find pastels to be a bit too loose and difficult to have autonomy over. But man, do I love to make them.

Pastels within our contemporary definition, “a crayon made with powdered pigment bound with gum or resin,” have been used for a few centuries, although if you figure natural chalks into that definition, they date back to prehistoric times. If used on archival paper, fixed to the surface, protected behind glass in proper conditions, and stored horizontally, pastel drawings can remain as vibrant as they were the day they were drawn for centuries to come. The binder does not yellow or crack, and high quality pigments should not fade dramatically. Oftentimes, it is the piece of paper that reveals its agedness rather than the drawing itself. The traditional binder for pastels is gum tragacanth (known on the streets as ‘gum trag’), although methylcellulose is often used as a modern substitute.

Left to Right: Gum Plant Engraving 39 published by Blackie & Son in Glasgow, Edinburgh, and London | Gum Tragacanth from Astragalus plant, www.kimiaeetrading.com/products/Tragacanth.html | Powdered gum tragacanth available for purchase, earthpigments.com/artists-pastels/

Left to Right: Gum Plant Engraving 39 published by Blackie & Son in Glasgow, Edinburgh, and London | Gum Tragacanth from Astragalus plant, www.kimiaeetrading.com/products/Tragacanth.html | Powdered gum tragacanth available for purchase, earthpigments.com/artists-pastels/

Without delving too far into the nitty gritty, gum tragacanth is a natural gum that is drained from the sap of the Astragalus genus of shrub-like plants native to the middle east. Like most natural gums, it has a whole slew of adhesive purposes from wrapping cigars, to making edible cake decorations, to binding incense. In the west, it’s notably less abundant than gum arabic or guar gum due to its comparable utility combined with the shaky trade relations with the middle east (both gum arabic and guar gum also come from parts of eastern Asia and Africa as well). It’s a versatile but weak, hygroscopic binder. Hygroscopic just means that it has a tendency to absorb water, which is arguably it's only major archival downfall. To make gum tragacanth concentrate from its powder form, you take 1 part powder and dampen it with pure alcohol in a clean jar. Then you add 30 parts distilled water and let it sit overnight, closed and at room temperature. The next day, you'll have a sticky, coagulated mixture. To finish off the process, you indirectly heat the jar of gum tragacanth by setting it in a warm water bath until the lumps have all smoothed out, leaving you with a solution about the consistency of honey. Gum trag can’t be used in thick films otherwise it'll crack, so to use it as a pastel binder you need to dilute it properly.

Each pigment has different chemical and behavioral qualities, making some very resistant to interaction and others super compliant. To accommodate some of these stark personality differences, we use the binder at various strengths or dilutions. This is not all that dissimilar from adjusting the oil to pigment ratio to make oil paint. Anyway, there’s a range of different dilutions that accommodate the vast variety of pigments for pastel making that all stem from the gum trag, which is too overpowering to actually use at full strength. Here’s a super useful diagram that I drew out while I was first trying to understand the dilutions/solutions, I’m sure you’ll find it easy to navigate:

I'm sorry.

I'm sorry.

Got it? No? Yeah okay I'm kidding. This was me trying to map out and visualize Mark Gottsegen's dilution instructions from The Painter's Handbook. Sometimes the whole "being a visual learner" thing makes better sense out of things, and other times it just makes a mess. The different solution strengths takes a minute to wrap your mind around, but it's pretty straight forward once you do. Pure Gum Tragacanth can be called solution A. You never actually use solution A to make pastels, but you dilute solution A to make solutions B through E. Solution B is one third the strength of A, solution C is one third the strength of B, solution D is one third the strength of C, and solution E is one third the strength of D. I find it easiest to make the dilutions in a relational way, building off the previous solution. If you take 2 fl oz of A, you'll add 4 fl oz of distilled water to make B. If you take 2 fl oz of B, you'll add 4 fl oz to make C, and so on. Essentially, you simply use the solution to wet and make a paste out of the pigment and filler when necessary. 

Pure Gum Tragacanth (A) in jar, and solutions B – E assembled. Notice the visible tone in Solutions B and C (33.3% concentration and 11.1% respectively) compared to the pure water look of solutions D and E (3.7% concentration and 1.2% respectively)

Pure Gum Tragacanth (A) in jar, and solutions B – E assembled. Notice the visible tone in Solutions B and C (33.3% concentration and 11.1% respectively) compared to the pure water look of solutions D and E (3.7% concentration and 1.2% respectively)

For as simple a process as it is to make a pastel, there are more details, nuances, and possibilities than could be imagined or accounted for. From pairing the pigment with the right solution, to finding a suitable inert filler (chalk or clay) to mix in with it, to navigating the ratios of pigment to filler, there's a wide array of variables on the table. A few very general rules of thumb: inorganic pigments can be bound with solutions B and C, with the exception of a few pigments that can be bound with E (or just water alone); organic pigments can be bound with solutions D and E, with the exception of a few that need something stronger like B. Unfortunately, there is no concrete list that exists to pair each pigment with its proper solution. Why not? Because a pigment, even if it is the same pigment with the same index number, is not necessarily the same depending on where it was mined or processed or developed. Even batch to batch in the same location can differ. It'll be similar, but not the same. So even if you find a list, don't be fooled. This is one of the many stopgaps in painting where vested pigment understanding demands itself to be known. I've got your back.

People often have the pureblood mentality that a pastel with all pigment and no filler is the purest and the most desirable. Again with the purity idealism. This is a misconception at best. While in some cases it's true that fillers are an adulteration to paint, in other cases they are inherently necessary for the paint to function and behave as desired. You likely won't need or want any fillers with a lot of the earth pigments, oxides, iron ores, etc. because they are dense, wet easily, and (with some exceptions) turn out pretty well without much trouble. A lot of the organic synthetic pigments are incredibly lightweight, so much so that they create a cloud of airborne particles at the slightest jostling. Having a pastel this lightweight would be inconvenient, and frankly, dangerous because of how readily ingestible the pigments would be. Not good. Using a filler can weigh down the pigment enough to form a solid pastel, and can prevent the pigment from puffing up into the air. You want to add in some filler, but not enough where it'll noticeably tint the value of the pigment. For something like a Hansa or a Napthol, you can add almost 50% chalk to 50% pigment without the color changing much, whereas for something with a lower tinting strength like a Sienna you're going to want to keep it 25% or maybe even less. Navigating the plethora of filler options is tricky– because of how many variables there already are, it's tough to examine the filler choice in an isolated, controlled way. Some of the go-to choices are ball clay, kaolin or china clay, calcium carbonate (coarse natural chalk), precipitated chalk (purified, refined calcium carbonate) marble dust (somewhere in the fine lines between calcium carbonate and precipitated chalk), and blanc fixe (inert pigment aka barium sulfate). Students have asked me "well what's the difference between this filler and that filler?" All bullshit aside, the difference is minimal. Best to get the hang of the process first and hone in on those details later when you've got it down.

Talking the talk is all good and well, but the walk is much more exciting! Here's your supply list for your pastel making setup:

pigment of your choice
filler of your choice
solution
clean disposable work surface (brown paper)
glass palette
palette knives
respirator mask*
rubber gloves*

*no really, be safe.

Here we've got a video collage showing each step of the pastel making process. On the top left we've got the pile of pigment, Quinacridone Magenta, that has been mixed together with the filler already. I put about 2 portion of blanc fixe with 3 portions of pigment. After you integrate that together with a palette knife, you slowly add your solution drop by drop, slowly and carefully so as not to over-wet the particulate. I used solution D. You can see in the video clip that the pigment resists the solution– if you dropped water into flour, it would be immediately absorbed. Notice the solution clinging to its round droplet form like little marbles, unable to easily wet the pigment. On the top right, we see the physical incorporation of the solution and particulate. Fold, knead, press, and grind the solution into the pigment as you gradually add it. Again, don't let it get too soggy! You'll know you're ready to form the lump into a pastel if it passes what I call the "touch test"– when you touch your (gloved) fingertip to the paste, it should pigment your fingertip without leaving any actual paste residue. If you pick it up and it sticks to your glove like cake batter, you've added too much liquid and need to add more pigment/filler back in. If you pick it up and it just crumbles apart, just go ahead and add more solution. Once you can handle it without it sticking to your glove too much, form it into an oval-like shape as you see in the lower left and set it onto your clean papered work surface. Finally, roll that baby up as evenly as you can! Or don't– you can square off the sides, roll it into a point, keep it as a big stump, whatever you want, really. 

Recent set of pastels that I made. I gave you my notes on how to make the Quinacridone Magenta– a magician can't reveal ALL her secrets!

Recent set of pastels that I made. I gave you my notes on how to make the Quinacridone Magenta– a magician can't reveal ALL her secrets!

Make sure you leave your pastel in the open air to dry for at least three days. If you close it in a box, a bag, or a locker, it could easily mold– remember that hygroscopic thing? Yeah. But after three days, feel free to put it into a box for safekeeping with your other drawing tools! Another note– take notes. Please. Do it for yourself. As you're making pastels, or really any material, you will always think you'll remember what you did, and I guarantee that you won't. If you make the perfect pastel, you're going to want to remember how you did it! And if you made a total flop of a stick, you're going to want to remember how NOT to do it next time. Science, folks. 

Finally, a little health disclaimer... while pastels are the most pure medium, they can also be the most dangerous. Don't let the lack of solvent put you at ease. Dry pigments are inherently a hazard because it's bad (but easy) for solid particulate matter to get into your lungs. When you make pastels AND when you use pastels (especially high quality pastels that are using real pigments rather than dyes), you should ALWAYS wear a respirator mask and rubber gloves. This is to be taken especially seriously when using heavy metals, which include cadmium, mercury, manganese, barium, lead, chromium, and cobalt, among others. Some of these are incomparably beautiful pigments and I totally get that. You shouldn't compromise your work for categorical suggestions, but you also shouldn't compromise your health for your work. Always wear a mask and gloves, and be sure to clean your work station after each use to take care of any particulate that has piled up.

As always, feel free to write me if you've got any questions or feedback. Happy painting!

Pastel drawings and mixed media works with pastels from the Prints & Drawings Collection at The Art Institute of Chicago spanning from the mid 1800s till the late 1900s. All images are credited to AIC.

1. Adolph Menzel | In a Railway Carriage (After a Night's Journey) | 1851  2. Berthe Morisot | "Self-Portrait" | 1885  3. Edgar Degas | Landscape | 1892  4. Edouard Jean Vuillard | The Avenue | 1899  5. Camille Pissarro | Church and Farm Éragny | 1895  6. Joan Miró | Woman | 1934  7. Max Beckmann | The Bathers | 1928  8. George Segal | Seated Female Nude | 1965  9. Jack Beal | Landscape-Lovegrass | (n.d.)  10.  Wayne Thiebaud | Cakes No. 1 | 1967  11. Jim Dine | Nancy Outside in July IX: March in Paris (Tulips) | 1980