It never dries. Or at least it can seem that way, if you ever worked with genuine Van Dyke Brown, a bituminous earth designated as Natural Brown 8 by the Color Index. Week after week can go by, and even the lightest touch of a finger on the thinnest of films can come away with a wet smudge of a deep dark blackish brown. It’s enough to push many a painter’s patience to the brink, and is a quality that has been bound to this pigment for as long as it has found a place on the artists’ palette, stretching back to the 17th century.
When confronted with this problem, a paintmaker only has a few options at their disposal. Certainly you can leave the paint as it is, although in many ways you are simply pushing the problem downstream and forcing artists to wrestle with the disparity of a paint that might take months to dry in a thicker application. Another possibility would be to abandon the pigment all together; to convert it to a mix of synthetic or natural earths blended with black. But to do so is to turn one’s back on a unique material that has threaded itself through so much of art history, and appeared in such a wide range of paintings forming the backdrop of our craft. Or you might try ramping up the addition of metallic driers in the hopes of coaxing the color into line. However, you soon find there is a limit to the improvements you can achieve before equally increasing the risk of cracking and surface defects. Not an option we would entertain.
In the end we went in another direction altogether, using a solution that has a long history of its own going back to at least Rembrandt’s day: namely, to leverage the powerful drying action that certain pigments are known to have – in particular the umbers. Start with a pure Van Dyke Brown and add 10% Raw Umber, and the initial film that never dried for weeks will now be locked down in a couple of days. Along the way, however, the masstone and tint are clearly impacted and its not clear if the gains are worth it. Slowly reduce that blend to a mere 2%, and the film will dry in a fairly reasonable 6-10 days with barely a perceptible change in color or handling. Reduce it even further to 1%, and the drying time starts to lengthen out again and even a paper-thin film can easily take a couple of weeks or more to set-up. Which gets you right back on that edge of a judgement call – when is long too long a time?
So it’s a balancing act, and a good lesson along the way in just how reactive and powerful a catalyst some pigments can be. If you look at the dry time chart at the end of our recent article Weighing in on the Drying of Oils (http://www.justpaint.org/jp25/jp25article3.php) you can see that a thin film of our Van Dyke Brown should dry in 5-14 days depending on conditions – approximately the same rate as our Cadmium Reds. We feel that makes sense and is in keeping with the traditional way painters dealt with this problem in the past. But if you ever have a desire or need for a Van Dyke Brown that takes longer to dry, or contains no Raw Umber whatsoever, just let us know! We regularly make custom paints for those in search of unique colors or formulations.
For more information about this or anything else, give us a call (800-293-9399 / 607-847-8843) or drop us an email techsupport@WilliamsburgOils.com