Originally Posted by DRAGGER
Medium density polyethylene with U.V. inhibitors and designed for containment of liquids of up to 1.7 specific gravity.
I am guessing that they simply have not tested the product with any alcohol levels higher than that.
PE is pretty tough stuff. It can take straight 100% ethanol and lots of other VOCs. IT's a common material to use when manufacturing laboratory bench top squirt bottles which get filled with all sorts of things.
What the material will do is leach polyethylene molecules from the surface into any fluid inside, which will produce off flavors. You'll smell most strongly when you first open the vessel up.
You can get the majority of it out by filling it with hot water & vinegar and letting it soak. After that, it'll only impart a slight flavor component.
It is a fact of materials sciences that all material have a vapor pressure. Diamond, gold, quartz, steels, the neighbor's cat, all polymers, - all materials have a vapor pressure. Material such as zinc, cadmium and plastics have enormous vapor pressure. Zinc and cadmium have vapor pressure so high that when plated on steel they can protect the base metal even when it's scratched because the atomic particles of the plating floating in the air (desorbed from the surface) a few molecule's distance high, tend to sublime back to the surface filling the scratches in the plating before ozidation can set in.
So you will always have polymer in your brew when using plastic.
I ain't saying that's a bad thing. It's just a fact.
Lots of people have good experiences using plastic fermenters.
If I were looking at a polymer solution I'd get those clear plastic PET fermenting carboys. They are cheap and tend to impart zero off flavor - at least none that the human can detect. PET is the material that soda bottles are made from. It's used exactly because it is so utterly flavor neutral and tough. Polyethylene is not flavor neutral. http://www.homebrewit.com/aisle/1041
If I were not planning to go SST I'd probably junk my glass carboys and get a few of those. Safer, way far safer than glass.
And for those who absolutely friggin HAVE TO HAVE a conical.
Those PET carboys can be inverted and fitted with a valve ( or a long hose with a plug).
And you can have more than one happily fermenting at a time 'cause they are so cheap. http://brewery.org/brewery/library/BrewCapKB.html