Can anyone give me some ideas on cleaning Pierco plastic foundation. I have a couple hundred sheets that I have cleaned old comb from. I scrape the old stuff off and have tried a power washer on it, have tried a wire brush and several others things. They just won't come clean.The best system I have come up with is to let the sheets soak in water and then use a power washer on them. This gets most of the stuff from the cells but you have to soak it a long time. Any help would bee appreciated.