The particular family of natural bituminous earth that we use in our French Cassel Earth is a notoriously slow drier. How slow? We are literally talking many weeks for even a paper-thin layer to become fully touch dry. Readers might recall that we wrote about a similar issue with Van Dyke Brown, which happens to be made from the same type of pigment. Borrowing the same traditional technique we used there, we have decided to remedy this by blending a very small smidgen of Raw Umber (less than 1%) into the mix, which brings the overall drying time down to less than a week. This addition is essentially unperceivable in terms of the color or handling and allows us to avoid using high levels of cobalt-mangenese driers.