Getting residue off enamel on side of a mobile home

Q. A residue has run down on the baked enamel-finished siding from a cooler atop the roof of our mobile home. Various products to remove the stuff have injured the enamel, only partly removing the residue. What will remove the residue and not hurt the paint finish?

Edward W. Venables

Clifton, Colo.

A. From your local janitorial supply company, obtain phosphoric acid descaler, at least 18 percent solution. Following labeled directions, scrub off the scale using a nonmetallic bristle brush. Rinse with clear water.

That ought to accomplish the scale removal while leaving the enamel finish uninjured.

If you can find the specific emission source, try to route the ''stuff'' so it will fall to the ground and not on the siding. Maybe a piping?