Pool Plaster Disc Grit Guide
Matrix non-corrosive diamond pool plaster discs are designed for controlled correction of rough plaster finishes. Use this guide to select the grit for the surface condition. For the surface-correction process, see How to Repair Rough Pool Plaster Surfaces.
Pool Plaster Disc Comparison
| Grit | Best For | Surface Types | Notes |
|---|---|---|---|
| 50 Grit | Heavy scale and very rough plaster | Marble, quartz, pebble | Coarse cut; use only where more aggressive correction is necessary |
| 70 Grit | Moderate roughness or blending after 50 grit | Marble, quartz, pebble | Medium cut; refines the coarser scratch pattern |
| 120 Grit | Final smoothing and surface refinement | Marble, quartz, pebble and other compatible plaster finishes | Fine cut; refines remaining texture after initial correction |
Choosing a Grit Sequence
Start with the least aggressive grit capable of correcting the roughness. Test a small, inconspicuous area first. The existing finish must be sound and suitable for abrasive correction; polishing is not a substitute for repairing damaged plaster.
- For very rough plaster or heavy scale, use 50 grit where necessary for initial correction.
- Use 70 grit to blend the 50-grit scratch pattern, or as the starting grit where it provides sufficient correction.
- Use 120 grit for final smoothing and refinement.
Not every surface requires all three grits. Remove no more material than necessary and inspect progress between passes.
Tool Setup and Use
- Tool: Use a compatible 7-inch variable-speed polisher or sander.
- Maximum speed: Do not exceed 3,000 RPM, or any lower maximum specified for the tool, disc, or backer pad.
- Backer pad: Use the MA7529 7-inch hook-and-loop backer pad.
- Technique: Keep the pad flat and use light, even pressure. Work in manageable sections, approximately 5 ft × 5 ft, and inspect regularly.
- Residue and heat: Remove residue between passes and monitor for overheating. Switch off the tool before inspecting or rinsing, and keep electrical equipment clear of rinse water.
- Safety: Follow the tool and disc instructions. Use appropriate personal protective equipment and effective dust control. Use GFCI protection with corded equipment.
Dry Use vs. Wet Use
Dry use is recommended with suitable dust control. Wet polishing may help keep the disc cooler and extend its life, but requires equipment specifically rated for wet use and must follow the equipment manufacturer's instructions.
Wet polishing does not mean operating a standard polisher underwater or in a filled pool. GFCI protection does not make a tool suitable for underwater use. Have a qualified pool professional assess safe drainage before undertaking work that requires an empty pool.
Non-Corrosive Diamond Matrix
These discs use a non-corrosive diamond bonding matrix for pool plaster surface correction. Surface refinement does not replace balanced water chemistry or routine pool maintenance.