Suggest you post this at www.johnbridge.com where they deal with thinset and tile and mortar.
Someone was helping us remodel and used thinset as the base and mortar. The pavers are set and we are trying to clean off the excess thinset. Now we realize they should have used mortar. Grooves look good but there is splatters of thinset. Also it is milky on the brick where some had been wiped when wet.
Ideas? Inside house.
Try a 50-50 mix of vinegar and water, let it sit, then scrub with a scrubby. If that doesn't work, increase to 100%. www.johnbridge.com is good for tiling questions.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014
Any homestore or tile place will have an acidic grout/mortar haze remover. It is best used before things set up too long.