Q. I have slightly off-white tiles in my small shower. The grout between the tiles doesn’t stay white. Three years ago, I cleaned it. It was a horrible job. Then I covered it with a sealer, another terrible job as it dripped onto the tiles and stayed there. However, the protection it gave the grout lasted until now. Recently I had somebody clean the grout and seal it. In a little better than a month, some of the grout is getting “black” once more. Is there a “painless” way to clean the grout? And what’s the best way to seal it?

STEFFI RATH, Woburn