>Wood frames, after a season or two, space the frames a touch wider than >when new, due to propolis builup. Pierco has thin contact areas to ensure >tight fit -- if the frames are crowded with a hive tool -- so this >widening effect will not likely ocur, making the tolerances more >important? Maybe Murray will comment. > I would agree fully with this. The spacing is definitely just a little bit narrower than the normal USA/Canada wooden frame, even when these are new, although it is very close to British normal. This does make the situation significantly more sensitive to defects in the spacing, hence our experience of bald patches in some cases and brace comb elsewhere. Like Allen, our wooden frames with wire and wax are not always flat and indeed we have some combs which we should be ashamed of. We now operate an annual cull, but there are always quite a few (well, OK, a lot) slip through, and should be picked up next year. We had hoped Piercos would be the answer to this as they would be perfectly flat, and culling the bad ones would just have been a scrape off and return to hive situation done with the hive tool on site. Alas it is not that simple. All current new boxes we are setting up are North American wooden frames with Plasticell or similar foundation. We like it but thought Piercos would save the assembly work. If they can sort out this bowing/warping problem it probably still will. I note that Allen uses Permadent rather than Plasticell. My thinking on using the latter is that the bees draw less drone on it, and controlling the amount of drone brood is part of our strategy for living with varroa. (Hence the comb culling, something we did not greatly bother with before.) I also had a feeling that it would be more rigid and thus warp less in extracting than Permadent, which I must add that I have never used. We have had quite a bit of Plasticell in service in Illinois depth honey supers for some years, and it is as tough as old boots, never budging during even the tangential extracting we have to use for heather honey, and you just attack it with the hive tool if you need to scrape anything off. When we did that with Piercos they often put drone back in place, but with the extended side walls in Plasticell this almost never occurs. I have decided to give the more modern Piercos of the last couple of seasons another chance this coming year, however, but Allens experience, together with that of another Canadian I have heard of this year, suffering (albeit slightly) from a problem I had been led to believe was cured, makes me a little reluctant to splash out in too much haste. Unlike most people on this list, I would have some problem returning defectives from Scotland. Hope this helps, Murray ps. Allen, they never do flatten, and possibly get a little worse. -- Murray McGregor [log in to unmask]