The chalky residue is probably from the aggressiveness of the brush and the acid. I would use a honing powder to remove the chalky look you may need to start with a 200 grit powder then use a 400 powder, this should bring back most of the color then apply a water based color enhancing sealer.
If you’re looking to add some shine you could use Stone Lok from Richard James Chemical. If you need additional information call me.
John E. Freitag
The Stone and Tile School
I am doing a clean and seal job on a slate floor- I'm not exactly sure what type of slate it is, only that it is a blue/grey color with a little bit of texture to it. We've acid washed it with a green nylon scrub brush. The cleaning process is causing quite a bit of slurry, I believe due to the aggressive brush. Normally I could put a nice solvent based color enhancing sealer on it and it would take the chaulky look away. In this case we are limited to using an immpregnator sealer which leaves the slate with the chaulky look which the customer is unhappy with. Any ideas on how to get rid of the chaulkyness?
Mid Atlantic Stone Solutions
4607 Fayetteville Road
Raleigh, NC 27603
919-772-2155 (Main Office)