Let the tile set for 24 to 36 hours, and follow the clean sponge/clean water procedure again. You then use a clean, dry rag to wipe down the tiles, and another clean dry rag to polish off the haze.
If you let haze removal go for six months, the sponge and water technique won't work, and you'll need a commercial cleaning product instead.
If you know the name of the tile manufacturer, you might want to contact it to find out what is recommended for the tile so it won't be damaged.
If you buy a grout haze remover at the hardware store, test it first in an area that is somewhat hidden from view in the event it damages the tile.
Follow the safety directions on the product - wear gloves, long sleeves, and safety glasses - while you are working.
Q: We live in a home that was built in 1939. The bathroom has a tub and a separate shower.
The walls of the shower are completely tiled in subway tiles, which are in good shape, and still secure after all these years. The grout is in good shape also.
However, some of the tiles are discolored. At first, we thought this might be mildew, but treating the tiles with mildew remover or bleach did not remove the discoloration.
On closer inspection, it appears that the discoloration is behind the glaze, which would explain why the bleach did not work. No tiles other than those in the shower are discolored.
We had several contractors in to look at the problem, but once they saw it was wet bed construction, they never even gave us an estimate - not only were they not interested in replacing the entire shower (which we were ready to do in desperation), but they did not suggest replacing individual tiles either, a difficult job because the grout lines are very narrow at 1/32d of an inch.
Also, we were concerned that replacement tiles would be a different shade compared with tiles that were in place for more than 70 years.
