I scrape the sediment out into a container that has a lid. Then I use the beautiful gray mixture to coat my plein air boards for a coloured mid value ground. This facilitates a fast pace while painting plein air since a mid value already exists for the painting - just add darkest dark and lightest light.
In this case the sediment is a warm gray. I use left over paint from my palette in the same manner. The result is an array of coloured grounds to choose from. The grays are particularly useful when painting tonally. However, they are brutal when painting the effect of light on local colour. There I most often start with a white canvas which is covered very quickly with flat colours for the major masses.