And while I was searching for more information on Sodium Acetate for the previous post on sealing concrete, I came across a way of simulating the natural patina that appears on rocks that have been exposed to air  – especially desert air.

What interested me about this information was that you can obtain different colours by varying the dilution and mixture of different metal sulphates and acetates.

Go to :: http://www.patentstorm.us/patents/5308646-description.html ^{[LINK BROKEN]}