My Great-Grandmother said they used to seal the interiors of old wood caskets used for water and other liquids with Pitch. She couldnt recall what Pitch is exactly, but evidently it worked well.
Offered by Ivy.
In Australia most people own rainwater tanks and when they need repairing we coat the inside with pitch, we call it blackjack it is the residue from distilled coal tar, commonly called bitumen used for roads and tarmacs.
Offered by Jan.
My understanding is that Pitch is made by cooking down the sap from pine trees, at least this is one method.
Offered by Ron.