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Grouting behind sink not lasting

Posted: Thu Dec 13, 2018 3:19 pm
by Spam Jelly
Hi,

I've had the grouting behind my sink re-done twice, and it looks good for about a month before it starts to deteriorate. Why doesn't it last? Is my contractor using cheap caulking?

Re: Grouting behind sink not lasting

Posted: Thu Dec 13, 2018 3:44 pm
by A. Spruce
Is it grout or caulk? If it's caulk, what kind of caulk is being used?

Re: Grouting behind sink not lasting

Posted: Thu Dec 13, 2018 4:35 pm
by Shannon
If it is grout (its not clear by your post) it could be that they are using sanded grout and that will not work well on such a tight grout line. I personally would use a good silicone or moisture resistant caulk instead but a non sanded grout should work.

Re: Grouting behind sink not lasting

Posted: Fri Dec 14, 2018 12:03 am
by Aaron
Also, you have extreme close-up in your pictures... it would be helpful if you had some zoomed-out pics to understand what we're looking at. Typically grout is for joints between tiles, and sanded caulk (that mimics the grout) is used for 90-degree inside corners (as different planes can shift slightly, the caulk has elasticity).

Re: Grouting behind sink not lasting

Posted: Fri Dec 14, 2018 4:54 pm
by Spam Jelly
Here's another picture of it.

My contractor said he used painter's caulk from Sherwin Williams...

Re: Grouting behind sink not lasting

Posted: Fri Dec 14, 2018 5:07 pm
by A. Spruce
That would be your problem, painters caulk is not "tub and tile", which is specifically formulated for wet locations. Moreover, it is likely that there was moisture in the joint at the time the caulk was applied, which affected adhesion, curing, and durability.

I prefer acrylic latex tub and tile caulks because they are MUCH easier to use, especially for the novice, and, when they fail, they can be scraped out and reapplied. Which brings us to silicon caulk. Silicon is much harder to apply in a neat and clean manner ESPECIALLY for the novice. Silicon is a repellent material, meaning that it resists things sticking to it including new silicon, so when silicon caulk fails, and it will fail, it is extremely difficult to clean the surface well enough to get anything to stick, including more silicon. Even though that new, fresh bead of caulk looks great, it won't be long before it's peeling off because of the previous silicon.

That is why I prefer acrylic latex caulk. If I need something that remains super stretchy, I reach for an elastomeric or beutyl caulk.

Re: Grouting behind sink not lasting

Posted: Fri Dec 14, 2018 5:14 pm
by Shannon
Painters caulk is not the right product. I like products like GE silicones for these areas and that's what I use all the time. I don't see failures.
Spruce says he finds silicone will not stick to old silicone but I have never really found that myself?

Re: Grouting behind sink not lasting

Posted: Fri Dec 14, 2018 5:17 pm
by A. Spruce
Maybe they make it different in Canada than they do here in the States. :P

Re: Grouting behind sink not lasting

Posted: Fri Dec 14, 2018 6:00 pm
by Aaron
There's a "siliconized" acrylic caulk. That's the stuff I like for everything.

That bad joint will need to have all its old caulk removed. Best bet is to use anything that can scrape it out, but not mar the marble. A heat gun might help to soften it to peel it out.

Re: Grouting behind sink not lasting

Posted: Sat Dec 15, 2018 5:54 am
by DanM
I'll throw my vote in with Aaron for the siliconized caulk. I find it a lot easier to work with than pure silicone stuff, and does a better job than regular caulk. Pure silicone is probably a little better for the long term but my joints don't look anywhere near as good, and it drives me nuts trying to apply that stuff lol.

Re: Grouting behind sink not lasting

Posted: Sat Dec 15, 2018 6:49 am
by Shannon
I honestly have never really noticed a difference in applying silicone vs. caulking? I have applied a few 100 miles of both in my life for sure, that is interesting.

Re: Grouting behind sink not lasting

Posted: Sat Dec 15, 2018 12:25 pm
by Spam Jelly
The counter is quartz. Will heating it harm the surface?

Re: Grouting behind sink not lasting

Posted: Sat Dec 15, 2018 12:27 pm
by A. Spruce
Spam Jelly wrote:
Sat Dec 15, 2018 12:25 pm
The counter is quartz. Will heating it harm the surface?
gently heating with a hair dryer shouldn't be a problem. Do a wider area than just the caulk joint to minimize the heat stress.

Re: Grouting behind sink not lasting

Posted: Sat Dec 15, 2018 4:29 pm
by Spam Jelly
After heating it with blow dryer, just peel it off and reapply?

Re: Grouting behind sink not lasting

Posted: Sat Dec 15, 2018 4:46 pm
by A. Spruce
You're probably going to need a razor knife or paint scraper to get it clean, but yes, clean out the old as best you can, clean and dry the surfaces, then apply the caulking of choice.

After you lay the bead, use your finger to lay if off, 3" to 6" at a time, wiping finger off in between strokes. Finish the joint with a single swipe. If using latex caulk, wet your finger before all swipes.

Re: Grouting behind sink not lasting

Posted: Mon Dec 17, 2018 9:01 pm
by Spam Jelly
Ok,I’ll give it a shot soon!