Quick Answer

Polish concrete to 150 or 200 grit before applying dye - not to high gloss. Dye needs an open, clean surface to penetrate; a floor polished to 800 grit will not absorb dye and will show it as a sitting film. Grind through 30/40, 60/80, 150 metal, then use a ceramic transitional pad to open the pores, vacuum thoroughly, and apply dye. After dye dries, continue through 400, 800, 1500 and 3000 to polish the color in.

Why Dye Goes On at 150 Grit

Concrete dye (both acid-based and water-based) works by absorbing into the cement paste. At 150 grit, the surface is open and porous - the dye sinks in 0.1-0.2 mm. At 800 grit, the surface is densified and polished shut; dye sits on top and looks painted. The industry standard is 150-200 grit for dye application.

• Too coarse (30/40) - dye pools in deep scratches, looks streaky.
• Just right (150-200) - even absorption, uniform color.
• Too fine (800+) - dye does not absorb, wipes off.

Pre-Dye Polish Sequence

You are not polishing for gloss at this stage - you are profiling the floor for dye. Sequence: 30/40 metal (remove laitance), 60/80 metal (open), 150 metal (uniform scratch), then a ceramic transitional pad at 200. Stop. Vacuum with Hepa, blow compressed air into pores, then apply dye.

Surface Prep for Even Dye

Blotchy dye almost always comes from uneven surface prep. The slab must be uniformly rough before dye. A copper-bond transitional pad at 200 grit evens out porosity differences between troweled and ground areas. Do not densify before dye - densifier closes pores and blocks dye absorption. Densify after dye is dry.

Common Dye-Prep Mistakes

• Polishing to 400 before dye - color sits on top and wears off.
• Densifying before dye - pores closed, dye will not absorb.
• Missing vacuum - dust blocks dye absorption in patches.
• Dyeing a wet floor - water dilutes dye and causes streaks.
• Skipping the 150 grit - 60/80 scratches show through the color.
• Applying dye when the slab is above 25 C - it dries too fast and streaks.
• Walking on the pre-dye floor - shoe prints block absorption and show as foot-shaped patches.

After dye dries and densifier cures, finish with resin polishing pads at 400, 800, 1500, 3000 to bring the color to a wet look.

Frequently Asked Questions

Q: Can I dye a floor that is already polished?

A: Yes, but you must re-grind it back to 150 grit first. Dye will not absorb into an 800-grit polished surface.

Q: Should I densify before or after dye?

After dye. Densify closes pores once the dye has absorbed. Densifying first blocks the dye.

Q: How long after dye can I polish?

Wait 4-6 hours (or overnight) for water-based dye to dry. Acid stain needs 24 hours and a neutralizing wash before polishing.

Q: Why is my dye blotchy?

Either the surface was not uniformly ground, or dye was applied too fast. Re-grind to 200, re-vacuum, and apply dye in two thin coats.

Conclusion

Dye lives or dies by surface prep: 150-200 grit, uniform scratch, no densifier, perfect vacuum. Then polish the color in through 3000. JOY TECH supplies ceramic transitionals and the full resin pad set for dyed floors; tell us your dye type for the prep sequence.