The can of bitumen mastic says I can add up to ten percent solvent to make the mastic easier to apply. Applicable solvents list follows. The problem is the mastic is so stiff tat if I put a stick vertically into the mastic it doesn't fall - just stands still so it's unclear how I would mix the mastic with the solvent such that it mixes uniformly and the process takes reasonable amount of time.
What's the procedure for such dilution?