Removing Black Mastic From Particle Board

With careful work, you may be able to restore your particleboard.

Black mastic is a strong adhesive used to adhere tiles to particleboard flooring. If you remove your tile to find black mastic beneath it, it's a good sign that you're dealing with old tile. Newer mastics are tan in color and much easier to remove. One of the only ways to remove black mastic without getting rid of the particleboard itself is to apply a mastic remover. However, while effective, these harsh solvents produce noxious chemicals. Take care to read all of the label's safety precautions before proceeding with the removal.

Things You'll Need

• Fan
• Gel mastic remover
• Paintbrush
• Putty knife
• Rag
• Solvent
• Water
• Trash can with liner
• Towel

Instructions

1. Maximize the amount of ventilation in the room. Open all of the windows and place a large fan in the door to increase airflow.

2. Paint the remover onto the mastic with a paintbrush.

3. Leave the remover on the mastic for the amount of time recommended by the manufacturer or until it softens to a gel.

4. Scrape the softened mastic and remover off the surface of the particleboard with a plastic putty knife. Hold the putty knife at roughly a 30-degree angle to the particleboard to avoid gouging the surface. Dump the excess goop into a nearby trash can.

5. Moisten a rag with the neutralizing solvent recommended by the manufacturer. Wipe the scraped surface down with the neutralizing solvent. Rinse the rag as often as necessary.

6. Wet a clean rag with water, wring it out and wipe the surface clear of the solvent used in Step 5.

7. Wipe the surface dry with a towel.

Tips & Warnings

• Before you apply the mastic remover to the entire surface of the particleboard, test the removal method on a small, inconspicuous section of the particleboard. If the board warps or chips, stop using the mastic remover.

• You may have to remove the particleboard altogether. The only other alternative to chemical removal is sanding. However, some older formulations of black mastic are made with asbestos. Call a contractor to test the mastic for asbestos before attempting to sand it away.

• Apply the mastic remover to 4-square-foot sections of the floor at a time. Working within a limited area will make it easy to apply and remove the product within the time limits set by the manufacturer.

References

• Armstrong: FAQs - Subfloor Preparation (Technical)
• Titus Restoration: Mastic Removal
• RadonSeal: Frequently Asked Questions
• City of Portland Online: Adhesives, Sealants, Primers and Paints