“How To Make Oil Pastels” by Kenneth Leslie -exerpt from Oil Pastel: Materials and Technique for Today’s Artist
What You Will Need:
Blended White Beeswax
A large can that fits in an old pot, to serve as a double boiler
Large palette knife
Soft clay or homemade modeling dough (see recipe below)
Plate glass or plexiglass on which to grind pigments
Rubber gloves to protect hands from hot drips
(Recipe for modeling dough)
1 1/2 cups flour
3/4 cup salt
1 1/2 cups water
1 1/2 tablespoons cream of tartar
3 tablespoons vegetable oil
Mix all ingredients together in a pot over medium heat, stirring constantly, until mixture is thick and no longer sticky. turn out onto waxed paper to cool. If stored in a sealed container in the refrigerator, the dough will keep for months.
WARNING: Many of the ingredients are highly flammable, especially the wax, mineral spirits, and oil. Most pigments are toxic in some way, and many people are highly allergic to them. Wear proper mask to avoid accidental inhalation of pigment dust. Do not mix oil pastels with improper equipment orin an inappropriate space. Do not try this in your kitchen – only a well-ventilated studio, when you are fully alert. Unless you are experienced, use only the safest, least toxic pigments. Stay away from cadmium, lead, arsenic, and other highly toxic pigments.
Instructions for making oil pastels:
1. The first thing you must make are molds for the molten pastel mixture. Heavy duty aluminum foil works well. Tear off a 20″ by 6″ sheet and fold the length in thirds, for a thick, stable wall. Lay the foil flat on a table and place a dowel that is the thickness of the desired pastel in the middle. A broomstick works quite well. Bring the ends of the foil up to meet, and roll them together back down to the dowel, to make a strong, sealed seam. Slip the foil tube off the dowel, and implant it in a lump of modeling dough or clay, to hold it upright while pouring into the molds. You will need several molds, enough for the volume of pastel you are making. Other shapes (square, triangular, and so on) are also possible, folded without a dowel, if the seam is well sealed.
2. Prepare a can for pouring molten pastel by bending the lip into a V with a pair of pliers. This will eliminate the need for a funnel later. Pour the dry pigment into the can. Because you’ll be adding more ingredients, and you will want to avoid spills, fill no more than a third of the can. Make a paste by gradually stirring in as little turpentine as possible.
3. Dump the pigment paste onto a palette — plate glass or plexiglass is best. With a large palette knife, grind the paste until it has a smooth consistency with no lumps. Return the paste to the can, and cover it to keep it moist.
4. Break up the beeswax into chunks and put it into a clean can. Put the can into a pot containing a few inches of water. If the can floats a bit, spill out some of the water in the pot, to be sure that the can of wax sits on the bottom. Put the pot on a hot plate. Don’t use a burner with an open flame, because that poses too much of a fire hazard; an electric hot plate is safer to use. On medium heat, slowly warm the water bath, until the wax thoroughly melts. You can stir it to separate the chunks.
5. Remove the can from the water bath, and carefully pour in stand oil at a ratio of one part oil to three or four parts wax by volume. Too much oil will produce a stick that won’t harden, but you need enough to make a creamy pastel. The cold oil may solidify some of the wax, so return the brew to the water bath until it is smooth again.
6. Remove the oil/wax concoction and pour some of it into the can of pigment paste. Again, varying the proportion of pigment to oil/wax will give you different results. The matter is further complicated by the fact that various pigments absorb oil differently, as discussed earlier. Any good handbook on artists’ materials will list the absorption ratios of pigments, which will serve as a guide for how much oil/wax you will need to mix in. Start out with equal parts pigment and medium. The brew should be as thick as you can make it without being grainy from too much pigment. The more oil/wax used, the more transparent the pastel will be, allowing more of the paper or undercolors below to show through. If you don’t use enough oil/wax, the pigment won’t bind together sufficiently and the resultant stick will crumble when you try to use it. (If you don’t like the consistency of the finished sticks, simply melt them down again and adjust the recipe.) Reheat the brew in the water bath, and stir it until smooth and creamy.
7. Using the V lip bent into the can, it is fairly easy to pour the mixture into the molds. There will be some spilling and ripping, so be sure to work over newspaper or a drop cloth. Keep one gloved hand on the mold as you pour, to be sure it won’t tip over. After the pastels have cooled and contracted for a few minutes, “wells” will form in the center, which can be refilled with more molten pastel.
8. Allow them plenty of time to cool — several hours — or they will crush when you try to use them. You can speed the cooling up a bit by putting the sticks in the fridge. When cold they will still seem quite soft, but after a week or so, they will cure a bit more. If you have poured without drips, the same mold foil can serve as a wrapper. Peel off only an inch from one end. If the mold foil is messy, remove it and replace it with a fresh foil wrapper. Store extra sticks in their foil with the ends crimped down to keep them fresh.