Thanks, bobad; the notion of food grade mineral wax hadn't penetrated my grey matter.

And, in Foolestroupe's defence, he may have been confused by the use of acetylene to induce ripening in pineapple plants. I don't know if it's still done but, in times past, a small granule of calcium carbide would be put in the head of the plant; water would react with it and produce acetylene.

Cheers, Rowan