Flamemaster Part B

I just finished up my tanks. I still have a decent amount of the Part A compound left over, but I'm scraping the bottom of the Part B. I'm sure that's simply because of the sensitivity of my scale, so with each batch I mixed up I probably used slightly more Part B than was necessary. A little bit extra each time over that many sessions adds up. Anyway, I haven't seen any place where I can just buy a small amount of Part B. Do I just need to toss the Part A once I've completely exhausted Part B? I don't need any more sealant at this point, but hate throwing it away since I know there are probably times in the future where it would come in handy.