I moved into a house that has about 800sq ft of 12" X 12" tera cotta (I
think) tile floor. Some of the areas with high foot traffic are not sealed
anlonger. This is obvious after damp mopping and seeing the places where
the water "stains" the tile until it dries completely.

In places with no foot traffic the surface finish seems like a "semi gloss"
finish.

Questions that I hope you can help me with...

Do I need to "strip" off the old sealer before applying new? If so, what do
I use?

How can I tell the type of sealant used before? e.g. water based or ???
something else?

Obviously the floor needs to be clean - is there any other surface prep?
Will the new coating of sealant adhere to the old?

Do I need to use more than one coat of sealant???

What brand sealant have you found that works the best? Is the most durable?

Any other tips/hints would be much appreciated..

Djay