Williamsburg Handmade Oil Colors are ground in pure, premium, alkali-refined and PH balanced linseed oil and made in batches no larger than five gallons at a time. This gives total control over the product, much like the late nineteenth-century French color makers. All the materials are hand measured, and every ounce of paint is scrutinized. The paint is packed in 40 ml and 150 ml non-reactive aluminum tubes. Much of the quality of oil paint is in the grinding. Some paint will feel slightly gritty; some, extremely smooth. Each color is ground to enhance the beauty and luminosity specific to that particular pigment.