How to Seal Plaster Fireplace Glaze

Clean the outside of the fireplace using rough scrub brushes, soft cloths or other materials suitable for the material used. If a heavy plaster was used, you may need to rub slightly. Do not create so much friction as to wear off the finish. If only glaze has been painted onto your fireplace, use a very soft cloth to remove dust accumulation.

Create a safe paint area around the fireplace to avoid drips from your sealer. Place painters tape on all adjoining walls and edges touching the fireplace. Plastic drops and tarps and cloths placed on the floor protect your flooring.

Roll on a clear, water-based polyurethane sealer. Use a water-based sealer because an oil-based sealer has a stronger odor, clean up is time-consuming and the finish yellows over time. If rolling over a smooth surface, use a smooth or sponge roller. Rough surfaces require a rough roller. Light layers of sealer are needed. Do not apply thick, heavy amounts to avoid drips and a cloudy hazy appearance. Allow to dry for about 2 hours. Add additional layers for more protection against wear and tear.

Slowly take off all painters tape. Remove tape slowly to avoid causing distress to the glazed fireplace. Remove all drop cloths and painters cloths. Clean all rollers and tools so you can use them for your next paint project.