I remember experimenting on the concrete globs left on a brick, it really
went to work there, bubbling and so on. I would get a library book on pottery,
mine are long gone or I could help you with this formula.
Copied from "The Gentleman's Guide to Passages South"
Muriatic acid (HCI) mixed with lots of water will:
1. eliminate rust stains on carpet, clothes and gelcoat chalking when mixed
with 1:10 in a spary bottle
2.make your corroded 12 volt deck sockets work instantly if sprayed into
3.keep your coolers and heat exchangers (diesel engines) bright and new
inside when mixed 1:8 (stainless and copper only, not aluminum)
4.Keep your head (boat john) clean and unclogged by calcium buildups when
5. become part B of two part teak cleaners when mixed 1:4 with water. Plain
old lye crystals (small can of toilet bowl or drain cleaner) and water become
part A (NaOH). be sure you have pure lye and not some explosive mixture.
The above is what ocean cruisers could not do without.
Forget US products once one leaves the States, Bon Ami, Mr Clean and Dow do not
exist. This is not battery acid, it more what is sold today as scum and calcium
deposit removal. Of cource any muriatic mixture should not be allowed to sit too
long without being flushed away with salt or fresh water.