So I have taken on the tedious task of restoring the headlight housings on my 67. I have separated the chrome grille's from the cast aluminum backs. I have polished the fronts of the grille's with buffing wheels on a dremel and chrome polish. I noticed that on the sides of each bar on the grille that there is a hardened buildup of dirt left over from many years of people just washing the front of the headlight housings during car washes. Of course we all know most folks thought of these cars as daily drivers and did not take the time to "thoroughly" clean each bar, front and sides, on the grille allowing the dirt to accumulate over time to the point where it has become a hardened plaque. My questions is, is there a chemical or something I can soak these grille's in to soften the "plaque" to where it comes off easier? because dremel wire wheels are a bit expensive.