I just finished grouting a 30 sq ft bathroom floor. I used mapie sanded grout straw color. It has been drying for 24 hours. It seems that there is a whitish/biege-ish residue on the very top layer of the grout. If I take a screw driver and scratch off the top layer I can get the normal color. The grout is solid, like a rock. Just has this residue on top of it. I can see it if I get down on the floor and look closely. Has anyone encountered this before and can you recommend a simple way to remove the residue. I have seen suggestions of the use of vinagar and water. I plan on sealing the grout but I want to wait until I have this issue resolved. I used minimal water in the preparation and washing steps, I mixed with a power mixer and let it slake properly with an additional mix after.

Thank you for your help!

Uh, oh, hate when that happens. Try a tooth brush a 50 50 mix of white vinegar and water in an out of the way spot. You want to let the rout cure for about 3 days or so first. Any harsher haze removers and you want to wait up to 10 days. When you are done scrubbing an area, rinse well and dry with a microfiber cloth. If that doesn't work, if the grout returns to its proper color when wet, you could try an enhancing sealer. An enhancing sealer gives a "wet" look. The problem in your case is the completely small square footage. With that in mind, you might be best off with a grout colorant which will both seal and recolor. Also, check your private messages.

Thanks, I have seen that advice around and wanted to vet it with you guys before I tried. I think it will work, just looking at the grout up close, it just seems to be a very thin film. I will wait another 2 days before I try as per your suggestion. It actually looks very similar to the actual color and does not look that bad. So I am hopefull that even with a 50% improvement with the vinegar it will be the correct color. I want it to match the wall tile grout color. I selected the same color without sand for the walls, so I am reluctant to use a colorant. Do you think that regular aqua mix sealer after the vinegar will help it look a little better?

What about this:
StoneTech Professional Restore Acidic Cleaner it says it Cleans away hard water deposits, grout haze, efflorescence & soap scum. From what I read the problem I have is efflorescence .