Acrylic Painting Technique: Using Clear Tar Gel
by Tesia Blackburn
Clear tar gel is a unique polymer medium that is described as having a long rheology. The term rheologyrefers to the flow of polymers, primarily in a liquid state. What this means when describing clear tar gel is that it is extremely stringy and syrupy. It has a honey-like consistency that makes it wonderful to work with in the studio. I have a variety of ways I like to use it, and I’ll share those techniques with you here.
It’s the perfect medium for creating long lines on a surface. It’s also an ideal medium to add to your paints for creating texture. Clear tar gel can also be painted in layers to create skins that you can then use as collage elements for your art. Keep in mind that clear tar gel dries to a high-gloss finish, making it an ideal medium to achieve a resin-like surface on your paintings.
Acrylic Painting with Clear Tar Gel: Problems & Solutions
The picture at right shows layers that cracked and fogged because I left the window in the studio open overnight. The drop in temperature interrupted the drying process and trapped moisture that created the fog. I was able to repair it, but it took many days of work.
Air Bubbles: It’s important to get far enough away from the surface to achieve a variety of line thicknesses and puddles, but the distance from the surface may create bubbles in the tar gel because it gets aerated. You can pop the bubbles with a toothpick (a laborious process), or you can spritz the entire surface with a fine mist of isopropyl alcohol. Spray from a good distance and allow the alcohol to land gently on the surface of the acrylic. IMPORTANT: Always have adequate ventilation when spraying, and wear an appropriate mask.
Cracking: Cracking occurs when the layers of tar gel are too thick. There’s not a solution to cracking once it’s happened, so modify your technique on future pours. Several thin layers are better than one thick layer.
Drying: There are a number of factors that determine drying time of tar gel:
• Volume of the layer–thinner layers dry faster than thicker layers.
• Air flow and humidity–hot, dry environments promote faster drying time while cool and humid environments slow drying time.
• Surface–absorbent surfaces dry faster because the moisture in the gel evaporates more rapidly while non-absorbent surfaces (like molding paste, for example) will slow down the drying time.
Fogging: If you don’t let a layer of tar gel dry completely before adding a new layer you run the risk of trapping moisture that will then turn into a cloudy fog. If your painting does develop fog, try putting a fan on the back of the canvas to help the moisture evaporate. Sometimes, if you wait long enough, the fog will clear on its own. I’ve heard from one artist that it took three weeks to clear.
• Don’t mix more than 10% fluid paint in to tar gel or you’ll disturb the rheology (stringiness) of the tar gel.
• Don’t use a hair dryer or heat gun to dry tar gel because it will likely cause it to crack or craze.
• Don’t make layers of tar gel thicker than 1/8-inch.
• Do maintain the temperature of the room while the layers dry to avoid cracking.
• Do make sure each layer is dry before applying another layer to avoid trapping moisture that will then turn to a cloudy fog.
Click here to get your copy of Acrylic Artist (Winter 2015). In it, you’ll find a special section from Michael Skalka on how to protect your acrylic paint in the cold, a feature article by Patti Mollica on color value, the work of photorealist Bernie Hubert, and much more.
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