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Discussion Starter · #1 ·
Hi,

I am replacing some peeling caulk around my tub where it meets the marble surround. After removing the white caulk from some sections, I am seeing what appears to be a different kind of gray caulk beneath it. It doesn't feel like or appear to be mortar. Is this a second layer of caulk, and should it be removed prior to applying the new caulk (GE advanced silicone 2 - kitchen and bath)?

Here are a few photos - you can see the width around the tub varies. It looks like the gray material was used heavily where the gap is larger (roughly 1/4" or less) and so the white caulk in these areas is extremely thin. The gray material was used more sparingly in some of the thinner locations, and the white caulk was thicker in those spots.

Larger gap - with layer of white caulk placed on top of gray for reference:

Rectangle Grey Wood Floor Composite material



Thinner gap - white caulk removed:

Fluid Grey Wood Rectangle Tints and shades


thinnest gap, white caulk removed:

Grey Rectangle Tints and shades Ceiling Glass
 

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What makes you think that it isn’t the thinset used to adhere the tile above? It’s hard to tell from the photos, but in the first photo it looks to be quite thin, like the installer made an attempt to scrape it off after the tile was installed. Is it brittle, like thinset?

(If you post more photos can you put something in the frame to give scale, like a penny. The gap in that first photo looks huge, but according to your text it can’t be more than ¼”)

Chris
 

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if it is soft and spongy - it could be a filler, like backer rod or some other material the installer had on hand at the time.
 

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Discussion Starter · #4 ·
What makes you think that it isn’t the thinset used to adhere the tile above? It’s hard to tell from the photos, but in the first photo it looks to be quite thin, like the installer made an attempt to scrape it off after the tile was installed. Is it brittle, like thinset?

(If you post more photos can you put something in the frame to give scale, like a penny. The gap in that first photo looks huge, but according to your text it can’t be more than ¼”)

Chris
if it is soft and spongy - it could be a filler, like backer rod or some other material the installer had on hand at the time.
It feels a little less rubbery than the silicone on top of it. Doesn’t feel cementitious like thinset and it’s darker than the mortar between tiles. The very thin white caulk in the first photo was scraped off by me - I just laid it on top of the gray material for comparison. I’ll post a few more photos later with some reference objects.

Should I leave it in place before applying the silicone caulk?
 

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Discussion Starter · #5 ·
(If you post more photos can you put something in the frame to give scale, like a penny. The gap in that first photo looks huge, but according to your text it can’t be more than ¼”)
Chris
Here you go. The white caulk is just a loose removed strip from the same area for reference. I'm thinking I should probably leave the gray material in place - thoughts?

Door Ruler Wood Office ruler Rectangle


Brown Wood Coin Gas Tints and shades
 

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If it’s soft I’d dig it out, since that suggests it’s an earlier applied caulk of a different colour. The white caulk doesn’t look thick enough to do a good job sealing water out, so that would give more space to apply new caulk. If it’s hard then I’d leave it in place since it’s likely the thinset used to adhere the tiles (which is different from the grout that was applied afterwards to fill in the spaces between the tiles).
 

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Discussion Starter · #7 ·
If it’s soft I’d dig it out, since that suggests it’s an earlier applied caulk of a different colour. The white caulk doesn’t look thick enough to do a good job sealing water out, so that would give more space to apply new caulk. If it’s hard then I’d leave it in place since it’s likely the thinset used to adhere the tiles (which is different from the grout that was applied afterwards to fill in the spaces between the tiles).
I think it is thinset. I removed more caulk running vertically up the tub corners and the same material was there. Caulked over it and looks great. Thanks!
 
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