The Duller is available in a 4 ounce bottle. The standard mixing ratio is 1 1/2ml of duller to a 1 ounce bottle of paint. The mixing ratio of the duller can be customized to the artisan's specific requirements. Well respected shoe painters recommend as much as 4.5 ml of duller per 1 ounce of paint. By making this product available separately, & not incorporating it directly into our Leather Paint, every artist can create a unique custom look. We know of no other source for this essential product.