Venetian Plaster Used to Cover Brick Fireplace

Traditional Venetian Plaster

• Italians traditionally made Venetian plaster from aged, slaked lime and marble dust ground as thin as talcum powder. They aged the plaster in underground pits where it absorbed trace elements from surrounding rocks and combined with water. The result was almost as thin as paint and had to be applied in layers. Use a flexible trowel to apply grassello Venetian plaster, which means “fat” in Italian. Use a rigid trowel to apply the coarser marmorino plaster, which contains marble dust. Marmorino means “little marble” in Italian.

Polymer Based Plasters

• Low-end acrylic plasters mimic the looks of traditional Venetian plaster. Apply them in multiple layers to get the translucent effect of lime-based plaster. High-end acrylic-based plasters go on easily and require few coats. Lime paint, which mimics the effects of Venetian plaster, contains binders so you can brush it on. You burnish it the same way that you would finish plaster applied by a trowel.

Application

• Clean your bricks. Apply drywall mud or joint compound where necessary to build a smooth base. Cover your bricks with a matte primer or lime paint. When they are smooth and dry, use a flexible 6-inch drywall taping knife to apply the plaster. Lightly sand your trowel marks so they won’t show through. Apply from two to seven layers of grassello for a final plaster no more than 1/8-inch thick. Use a rigid trowel to apply a final coat of marmorino, a clear or colored grassello or a nearly clear material called lucido. The more you polish the plaster, the shiner it will get. If you want a high gloss, sand it with steel wool or fine sandpaper. After the plaster has dried for a few days, seal it with wax or a synthetic sealer.

Special Effects

• If you apply different colors, thin spots will show through when you burnish the plaster. Add antiquing material to make your plaster look aged or distressed. Add different colors to imitate marble or stone. Add extra darkness just above the firebox and in the crevices of your bricks to make them look as if they have accumulated soot for years.