der-seemann wrote:Sorry, but most plastic bags are made of PE (or PP). Both are good to use with sodium hydroxide as long as you don't use too high temperatures (PE) or too high concentrations of sodium hydroxide (PP).
I guess I am a bit late and the party is already over/got canceled. Just for reference, I would like to add some information.
Even though plastics may be labeled as PE or PP, that does not mean that polyethylene and polypropylene are the only ingredients or constituents. Apart from the additives such as polimerizing agents, manufacturers also add various types of functional additives like stabilizers, plasticizers and fillers in order to create plastics products with different performance characteristics. Plastics that are intended for use with watery food stuffs only are often quite different from plastics that are intended for use with fatty food stuffs, because fats can leach additives from the plastic that would remain untouched by water and water-solubles. Plastics that are intended for use with solvents, or for use with strong acids or strong bases may have different requirements and characteristics in turn.
Taking
any plastic and expecting it to not interact with any part of an extraction cannot be considered to be generally safe.
Regardless of the above, plastic bags are usually not mechanically robust. They tend to tear and rip easily, which can be a major hazard when containing corrosive substances. Do not use them for primary containment.
IMHO plastic bags do have a valid use for containment: Put your extraction liquids in glass jars or bottles, then wrap these in firm cloth, to contain the sharp glass shards that result from accidental glass breakage, and then finally place the cloth wrapped glass in a plastic bag (or two nested bags), to contain the liquids from seeping out.
BTW, the idea behind the tek you posted is sound, though not completely original. You are basically proposing a STB tek with integrated mini-A/B. Don't be disappointed if your first essay is not yet the golden version, most of the published teks are the result of many rewrites and polishings or are rewrites and polishings of earlier teks.