If the product smells like old model airplane glue, then the proper thinner would be toluene (aka toluol) or, preferably, xylene (aka xylol). You might get away with methyl ethyl ketone (aka MEK) or lacquer thinner. Or you might get a mess. It's hard to tell without trying.

But don't buy a $5 can of solvent just to thin a $1 bottle of head cement. It's cheaper and safer just to buy a new bottle of head cement.

And don't use nail polish remover as a thinner. The nail polish remover contains acetone, but also water and oily additives. The water and additives will do some nasty things to your head cement!


Tom