Wintering your Flow Hive / Flow Frames

[CheezWiz]

Well,

I happened across this thread where Flow states exactly which plastics are in the Flow Frames:

@Jake

The clear viewing ends of the frames are made from a virgin food grade copolyester. The manufactures have assured us that it’s not only BPA-free, but it is not manufactured with bisphenol-S or any other bisphenol compounds. The manufactures also say that third-party labs have tested this material and the results have demonstrated that it is free of estrogenic and androgenic activity.

The Center frame parts are made from a Virgin Food grade Polypropylene which is also free from any Bisphenol compounds and is widely accepted as one of the safest plastics for food contact. It has also been used for many years in beehives for both Brood and Honey combs.

That seems to indicate PETG on the ends, which falls into number 1 and has a temp range of -40c to 70c, and number 5 (PP) for the comb, which means 0c to 135c.

Everything I can find on PP states that is remains chemically viable at temperatures below zero but becomes very brittle and glass-like. So as long as they are handled with extreme care in the deep-freeze, all should be OK. PP is used for freezing organic samples at cryogenic temperatures.