NTC

The National Training Center for Stone & Masonry Trades

Stain Removal Guide

APPLYING THE POULTICE

Once the stain is identified, the following steps can be followed:

1. Clean the stained area to remove excess from the surface.

2. Wet the stained area with distilled water. Pre-wetting fills the pores of the stone with water, isolating the stain, and accelerating the removal by the chemical.

3. Prepare the poultice. If a powder is to be used, pre-mix the powder and the chemical of choice into a thick paste, the consistency of peanut butter. In other words, wet it enough so that it does not run. If a paper poultice is to be used, soak the paper in the chemical. Lift the paper out of the chemical and hold until it stops dripping.

4. Apply the poultice to the stain, being careful not to spill any on the non-stained areas. Apply approximately one-quarter-inch thick, overlapping the stain area by about one inch.

5. Cover the poultice with plastic (food wrap works great). Tape the plastic down to seal the edges. Allow the poultice to dry thoroughly. This is a very important step. The drying of the poultice is what pulls the stain from the stone into the poultice material. If the poultice is not allowed to dry, the stain may not be removed. Drying usually takes from 24 to 48 hours.

6. After 24 to 48 hours, remove the plastic.

7. Remove the poultice from the stain. Rinse with distilled water and buff dry with a soft cloth. If the stain is not removed, apply the poultice again. It may take up to five applications for difficult stains.

8. Some chemicals may etch the marble surface. If this occurs, then apply polishing powder and buff with a piece of burlap to restore the shine.

For further information on stain removal see our book: Stain Removal for Stone and Other Porous Surfaces.