I have been installing various ceramic/porclain tile for many years and have used several different kinds of sealer. Thi Old Grout is by far the best sealer on the market. We used it last year on our new home and today it looks as new and bright as the day we applied it. I am getting ready to re-do the grout on our other home in CO which has about 500 SF of 18" Italian porclain that has darkened and stained grout that is only 3 years old. I wish I would have known about This Old Grout. We tested a few tiles with the sealer we had left over from the new house and it looks terrific over the old stuff. We have found that applying this product over older grout that it's easier than trying to clean the heavily stained older grout - and looks much better, especially over a period of time.