Use is straightforward. The first cleaning is in the left-most jar. After using a paint brush comb put it in the middle jar and then finally the right most jar. As you use them, the left most jar will become the most soiled. When it is really soiled, discard it and move all the jars one slot to the left. Clean and refill the soiled jar and it now becomes the right-most jar. So essentially you always have a jar that is almost pristine. This helps really keep your brushes clean. I've found that if I can let the jar settle for a week that the solids fall to the bottom and then I can pour the paint thinner thru a filter and reuse most of it indefinitely.