How to Repair Cracks in Horsehair Plaster

What You'll Need
Plastic sheeting
Dust mask
Work gloves
Safety goggles
Bottle opener
Putty knife
Portable vacuum
Spray bottle
Setting compound
Sanding paper

Horsehair plaster is a type of plaster that has been mixed with actual horse hair, hence the name, creating a gritty, textured look and feel that has been used as far back as the 1800s. It is hard to find this type of plaster in newer, more modern homes since this technique has long lost its popularity due to its predisposition to severe cracking and crumbling with age. However, some older modeled homes still have horse hair plastered walls and ceilings, and some homeowners enjoy the antiqued look of horsehair walls, regardless of the superficial cracking that comes with them. In actuality, small cracks usually do not represent any real architectural damage and can be easily repaired using the right tools and following the proper preparation procedures.

Safety Tips

When performing this type of repair work, you must take extreme precaution due to the amount of loose dust, dirt and old plaster you will be releasing into the air. Older plaster compounds like horse hair plaster may contain many harmful chemicals, such as lead. Because of this, no children or pets should be allowed in the area while work is being done, as it is potentially dangerous to breathe in the loose particles that will be floating in the air. Protect yourself as well before embarking on this type of project by making sure your dust mask, safety goggles and work gloves remain secure during the repair process. 

Step 1--Prepare Room

Remove any furniture from the room you will be working in and put on your dust mask, safety goggles and work gloves to protect against loose plaster and dust particles. Lay down a plastic tarp or drop cloth to protect your flooring. Using the bottle opener, chip out any of the loose plaster you can find in each crack you are trying to repair. Avoid using undue pressure, as this could lead to unnecessary damage and need for further repair.

Step 2--Prepare Crack for Compound

Using the hose attachment on your vacuum, suction out any loose debris from the open cracks in your plaster. When you're done, mist the area lightly with water to reset the plaster. Allow the area to fully dry before proceeding to the next step.

Step 3--Apply Compound

Generously fill the cracked plaster with a quality setting compound. Using the putty knife, smooth the area and scrape off any excess compound before allowing it to fully dry.

Step 4--Sand and Prime

Allow at least 24 hours to pass before beginning the sanding process. Making sure your protective gear is once again in place, use a firm sanding pressure to further smooth out the repaired plaster, making clean swipes with the sanding paper. Once you are finished sanding, wipe the dried compound clean with a damp sponge. Prime the repaired area neatly, allowing the primer to dry before applying a coat of paint for the finished result.