There’s three types of tiles you mostly find in client’s home. One is porcelain, two is ceramic. Those two tiles are manmade. They’re made in factories. They always have a seal porcelain finish on the top.
Those tiles should only be cleaned and never sealed. The top tiles that must be sealed are natural stones. Some of them are as followed marble, slate, travertine in a lot of the other products, like a limestone, they should always be sealed. When you take a shower, each time you take a shower with heat and humidity and water, it does continue to thin out the sealer.
You should always seal your showers and or your stone every three to five years. You should also. Consider doing your vanities as well, because if you have a lot of products, toothpaste, that could easily etch your showers. Another thing, again, as I said before, you should never use anything kind of acidy for your cleaning products always result to a very good natural stone cleaning product.