Richard Nakka recently added a page to his site about harvesting aluminum flake from paint. Actually, there are several new additions to the igniter page that I found intersting. I'll defer to Richard's page about the usefulness of flake aluminum as a thermic agent for igniters and the harvesting details.
I haven't had much time to devote to rocketry lately, but this technique seemed so simple and the cost was so minimal that I decided to give it a try. One thing that I noticed was that the lip on the paint can made it difficult to get all of the slurry out of the can and it was difficult to determine how deeply to insert the siphon. Too deep and you just sipon out the actual aluminum. I ended up transferring the slurry to a baby food jar for the 2nd acetone wash. Not only was it easier to get the slurry out of that container, but being clear glass I was easily able to see when the aluminum had settled. It was also easier to see the placement of the turkey baster used to siphon out the acetone ensuring that a minimal amount of aluminum was siphoned out. I ended up with a yield of 34 grams from a half pint of Rustoleum 7715 aluminum paint which is easily enough for 50-75 igniters.