It is usually thick since it is also usually not all that strong. I think it is often 5/8" though there may be thinner ones.

Most folks want a clear sealer that has some gloss. I recommend MexSeal (or it may be MexiSeal). It will wear out and scratch off, but that's life.

If you want no change in the surface appearance, I WOULD recommend an invisible and permanent sealer that I sell, but that would be advertising, wouldn't it? :^) So try one of the other sealers and be prepared to reseal often. Porous Plus from Miracle will work for awhile.

Mexican pavers or Saltillo tile should have a penetrating sealer applied before installation. After installation and grouting I use 4 coats of Jasco Gloss & Seal for a glossy finish or Jasco Natural Look for a more natural finish. Great results and the finish lasts longer than any other product that I've used.