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Unread 01-25-2020, 06:47 PM   #152
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Join Date: Oct 2016
Location: Central Virginia
Posts: 468
Giving up on silicone

Here’s an update on the silicone problem I was seeing. Well, I dug out the worst of the silicone and replaced it with Mapei color matched silicone. The color matched well. However, in the areas that get hit with the water stream from about waist height down have been pulling away from the tiles. The areas that don’t get drenched are doing fine. It’s as if the water is dissolving out some small amount of substance from the silicone. The areas where I left the Color-rite silicone in are doing the same thing. I don’t think it’s differential movement as the upper seams are fine, as are the seams on the other side of the pony wall which are grouted. Maybe something to with the colorants or the more modern formulation as the upstairs bathroom that I did ~25 years ago and has gotten lots of heavy use is still doing fine. Used the plain white GE silicone on that.

Digging out the silicone was a fun exercise in itself. Used a razor to cut the areas from the tile and a dental pick to dig it out. Some came out in strips with a residue on the tile surface and others had to be picked out bit by bit. Lots of scraping to get the tile free of residue. I also used a Dremel with a small diamond pear bit to get the last bits. Fortunately, when I did the tiling, I used probably more mortar than I needed, so there was good coverage of the Kerdi and I hit the mortar before getting even close to the waterproofing.

The little water that got into the gaps probably took with it some soap scum and crap (I think the hair conditioner is a worse offender than the soap) and started mould sticking to the silicone edge surfaces. The tile was clean.
Anyway, contrary to the TCNA guidelines (as Cx would say “it’s your shower, do as you please”), rather than replace it and wait again, I got a fresh bag of grout (Ultracolor Plus FA) and grouted all the seams where there was silicone. (It came out a tad darker than the first grouting years ago, but certainly acceptable.) If it cracks at least the moisture can evaporate through the grout in the seams and dry out, I think the capillary action kept the silicone moist longer. When the shower was built, I grouted the floor to wall seams and they held up fine so far.

So a roll of the dice to see what comes down the road. Just an update for any future lurkers to be aware that getting the silicone out ain’t no picnic.
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Last edited by Gozo; 01-25-2020 at 08:21 PM. Reason: Auto-spell strikes again
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