What should I do if there is ash on the tiles of the balcony bathroom?

It is actually normal for the gaps between the tiles to have traces of cement, and if the color is very uniform and the gaps are not large, it can also achieve an aesthetic effect, especially if your tiles are plain, it is necessary to distinguish them in this way.

If it is ugly, it should be caused by too large a gap, you can refer to the effect of other people's installations to see if the quality of the project is not up to par. If it's a construction quality problem, go to the home improvement company to complain and ask them to rework!

But in my experience, the traces of the gaps in the newly pasted tiles are more obvious, and they will become less and less obvious over time.

If you are saying that the cement can not be wiped off after drying on the tile, it is very easy, many chemicals can be cleaned, and now many cleaning products that have been prepared and packaged are very convenient to use.

I know what you said, in the past, when our unit was renovated, it was also like this, and then it was scraped off with a small greasy knife, you can also try it, it will not hurt the tiles!

The gray has penetrated into the tiles, and it can't be erased

This is a matter of ceramic quality, and it has nothing to do with the builder

Buy a bottle of hydrochloric acid and wash it, and then rinse it twice with water.

To scrub with diluted oxalic acid (tile cleaner). Don't forget to protect your hands and wear rubber gloves when scrubbing. Apply it to the cement area with a brush first, and wipe it off with a dry cloth after 3-5 minutes.

Buy a pack of white cement or grout, and re-hook the seam.

It can be treated with caulk, and the usage is the same as cement. Specifically deal with such issues.