Cobra Study oil colour in Burnt Sienna 411 is a semi-opaque colour with excellent lightfastness ( and ). About Cobra Study Cobra Study is a water-mixable oil paint that offers the same fantastic results as traditional oil paints, without having to use harmful solvents. Cobra Study is made with the same high-quality pigments, and yet, with Cobra Study you can paint at an affordable price. This is because we offer only a selected number of colours and use less pigments that are not as finely milled as those used in the Cobra Artist series. Can be mixed and cleaned with water. Created with high-quality pigments. Affordable alternative for the Cobra Artist series. Available in 40 semi-transparent, semi-opaque and opaque colours with the highest degree of lightfastness ( and ). Cobra can be used in conjunction with traditional oils and when mixed at a ratio of Cobra 4:1, the mixture will retain its ability to be thinned and cleaned with water.