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Short Summary
Main recommendation: Use a different-colored cement (gray) when grouting a white grout job, so you can spot and fix every gap and leftover cement before finishing, since mismatched whites will show discoloration and texture differences later. The video demonstrates mixing, applying, and polishing unsanded grout (a Mapei polymer product) over a waterproofing membrane.
Key Points
- Clean tile lines and remove cement stuck between tiles during installation before grouting, which reduces later touch-ups.
- Grout is about 50% application and 50% preparation.
- Gray cement reveals missed spots that white cement would hide, and mismatched white tones would otherwise show up within about six months.
- Unsanded grout is tricky to mix; too much water early on makes it unrecoverable, so add water gradually.
- Use low-speed mixing to avoid color streaks from separation, such as red streaks in brown grout.
Details Worth Noting
Concrete instructions:
- Mix unsanded grout by adding a small amount of water at a time, mixing for about two minutes with a low-speed mixer, and checking for dry spots. Avoid over-watering, which leads to a soupy mix that can take three to four hours to evaporate/firm up.
- Work time for standard grout is about 20 to 30 minutes to apply and roughly an hour to wash off. Unsanded grout is firmer and harder to manage, so apply it promptly.
- Apply grout by starting at the bottom of the wall and working upward, then work from the top down at an angle, pushing back and forth into the grid lines in different directions to fill the joints fully.
- Remove excess grout from the wall as you go, since less grout left on the wall means less to wash off.
- For inside corners, use the rounded edge of the float on the wall that went in second to leave a concave fill rather than scraping grout out.
- Polish with a damp grout sponge (cheap, roughly two dollars at a hardware store), wringing it out so it's barely wet, using circular motions. Use each sponge for only one cleaning pass to keep it clean.
- Inspect for holes, dirt, and high spots, and use a grout remover tool to clean stray cement from affected areas.
- Clean the tub or work area so grout dropped there can be salvaged and reused.
- The project in the video was split over two days: demolition through tile on day one, grouting on day two.
- Gray cement reveals problems, but it means you must fix all of them before the client sees the job.
Bottom Line
Grouting quality depends as much on prep and inspection as on the application itself, and using a contrasting cement is a practical way to catch defects before handoff.
