I need a little help. I have the data sheet for a couple different types of paint that call for mixing by weight. How does that work. I have one that says 15 parts to 1 part. I need to mix small quantities and can't figure this one out either. 15 ounces to 1 ounce gives me a half a quart of paint and I don't want to shoot a whole quart but don't know how to extrapolate this down and have a correct mixture. Do you use a scale that measures in grams. Slicksand by evercoat is one of these and the other is a ppg product.