Ceramic tiles are covered with a glaze which basically is a coating of glass
like material that is melted onto the tiles in a kiln. Nothing should cause
the surface to have "watermarks" on the glaze as it is impervious to liquids
or anything that can soak into the surface.

However, if the tiles are thin and porous as some real cheap tiles are, you
possibly have a water problem behind the tiles. If they were not installed
properly, possibly not using a water proof backing, there could be water
penetrating the grout lines, especially if they were not done right. This
water could be soaking into the tiles from behind and showing up as wet
marks behind the glaze. As the water evaporates or is absorbed uniformly
throughout the tile or into the backerboard the wet marks will dissappear.

I don't think anything will cure this other than a total tear down and
replacement with cement backerboard, waterproof membrane, thinset mortar,
good quality tiles and a good grout. You may find a lot of mold growing in
the wet environment behind your tiles.

"1969Benz" wrote in message
ups.com...
Hi all,

Just bought a house that was "refurbished" by the previous owner. I
think she did all the work herself, or with the help of a builder
friend. Unfortunately, now it's my responsibility to fix bits of it
up that weren't done properly. After a couple of weeks I started to
notice that the shower wall tiles, after a long-ish shower, were
showing grey watermarks that started from the grout line and headed
toward the centre of the tile. Tiles are white by the way. The
watermarks varied in size from about thumbprint size to around double
that.

I've Googled for hours and been reading this newsgroup for the last 2
or 3 hours as well and am still not 100% sure how to proceed. And, I
should own up at this point, I've already removed ALL the grout (not
the caulk) in the shower and done it over once, including using a
paint-on sealer on the new grout a couple of days after the grout was
installed (?) - which didn't improve the problem!

It IS possible that I screwed up the mixing process for the (unsanded)
grout and made it too hard - it ended up sort of like putty and I was
told it should have been more like toothpaste.

My question is this: Should I attempt to do the job again, assuming I
can do a better job mixing the grout, or is there a bigger problem?

I'm not a home-handyman by any stretch of the imagination, but as this
is my first house I wanted to have a go at fixing a problem myself. I
haven't seen any other post about re-tiling or re-grouting that
mentions watermarks (darkened areas) on the tiles themselves, only the
grout lines. I think the tiles are reasonably new, within the last 6
months or so. The watermarks disappear after a few hours, but I still
worry that it can't be good for them to be appearing in the first
place.

I haven't called a professional because, just having bought the house,
money is still a bit tight.

All advice appreciated.

Cheers,
Ben.