Every time I read about someone's experience with the tried and true homemade seam sealer consisting of a 50-50 mix of silicone caulk and odorless mineral spirits, there's inevitably a comment about the difficulty the author encountered mixing the two ingredients.
It's true. The two chemicals don't readily dissolve into a uniform mixture, but there is a way to make it happen with little time or effort. Here's how:
Chuck a finish nail, I think I used a 10 or 12 penny size, point first into a variable speed electric drill. The kind that plugs into a wall is preferred because they generally spin faster. Now, bend the nail slightly so the head is roughly 1/8 to 1/4 inch off center.
Place the ingredients in a shallow vessel which you can make by cutting off the bottom 2 or three inches of a soup can, and stir with your drill-nail-stirrer. It's best to plunge the nail into the ingredients before starting the drill spinning to avoid splashing. If air is getting entrained into the mixture, you're spinning the stirrer too fast. If after a minute, you don't have a uniform mixture, you may have forgotten to plug in the drill.
A one inch disposable foam brush makes an excellent applicator. Proceed without dawdling. The mixture will begin to set up in maybe five or ten minutes.

