Hi Steve, A good test of plastics for caps is to put it in a microwave oven. If it gets warm it is no good as a cap dielectric. Never tried this myself,I got it from the archives.But it seems to make sense. I might sell some of my surplus caps at the testlathon, as I am sold on the mmc design. cheaper quicker and easy to replace. can I say more? Let me know off list if you are interested. cheers bob golding