Quick Answer

Use PCD tooling or coarse metal-bond segments on a floor grinder to remove old glue, then one medium-grit pass to clean the residual film. PCD (polycrystalline diamond) discs shear thick adhesive without loading, while a medium metal disc cleans the last film so tile thinset bonds properly. The floor must end clean, flat, and free of residue.

Why Glue Is Hard to Remove With Regular Grinding

• Adhesive gums and loads resin and fine metal segments.
• Heat from grinding melts glue back onto the concrete.
• Old glue hides low spots that appear after tiling.
• Leaving residue causes tile delamination later.

Tool Selection for Glue Removal

Adhesive condition	Best tooling
Thick carpet glue (2-5 mm)	PCD tooling such as the WerkMaster PCD Tooling for Coating Removing (JOY-WM-PCD1R1)
Thin residual film	Coarse metal segments (30-50 grit)
Mixed glue and mastic	PCD first pass, metal second pass
Very large areas	Heavy grinder with triple-head plates

Step-by-Step Removal Process

1. Test a 1 sqm patch to check glue thickness and hardness.
2. Run PCD tooling at low-to-medium speed with light pressure — let the diamonds shear the glue.
3. Vacuum continuously; glue melts if it builds up heat.
4. Switch to coarse metal segments like the Diamond Trapezoid Grinding Disc (JOY-TP-R3) to remove the remaining film.
5. Check for residue with a damp cloth — a clean surface shows no dark film.
6. Do a final medium pass to open the surface for thinset.

Common Mistakes That Ruin the Subfloor

• Grinding glue that is still soft — it smears instead of shearing.
• Heavy pressure, which heats and re-deposits the adhesive.
• Skipping the test patch, then discovering the glue is not grindable.
• Leaving a glossy patch that thinset cannot grip.

Frequently Asked Questions

Q: Can PCD tooling remove all types of glue?

A: PCD shears most mastics and carpet adhesives. Some rubber-based glues need chemical softening first. Test the patch to confirm.

Q: Do I need to grind after PCD removal?

A: Yes, a coarse-to-medium metal pass cleans the residue film so the surface is porous enough for thinset.

Q: Is chemical remover better than grinding?

A: Chemicals work on thin films but take time and leave residue. Grinding is faster and more predictable on large floors.

Q: How much glue can one PCD disc remove?

A>Varies with glue and floor, but typically hundreds of square meters when used at the right speed and pressure.

Conclusion

Grinding is the fastest reliable way to remove old glue before tiling. PCD tooling clears thick adhesive, and a medium metal pass leaves a clean, grippable surface. Contact JOY TECH with your glue type and floor size for a PCD-plus-metal tooling package.