What would cause grout to immediately discolor and fail to harden?
Yesterday was the third time I regrouted a section of a shower floor. All of the grout starts out light gray, but several hours later the problem spots are still gray while the rest has dried white.
The discoloration occurs at the angle between wall and floor, and the tiler left a rather large, deep gap to be grouted. I figured such a large section of grout just needed a longer time to dry out, but weeks later it was still gray and not fully hardened. Each time it has been easy to dig out and not at all brittle.
This time I’m going to try filling the most of the gap with some kind of caulk, in the hope of sealing off whatever is causing the problem. It may take care of the problem, but I’m still curious as to what in the shower could affect grout like this. Soap scum?–cleanser?
Janet
Replies
I'm wondering if maybe silicone caulk was there before. Was it tiled before? Maybe old grout sealer ran in? Just guessing, someone who knows more about tiling may have a better answer.
Janet, all I can think of is that maybe your grout cleanup was done with too wet a sponge. Along the walls/floor area lead me to this conclusion. Too much water could wash away the cement from the grout. If you're using this shower b/4 the grout cured, then maybe soap or detergent could be a problem.
How wide are the joints and did you use sanded or unsanded grout?
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Yea, sounds like you keep saturating the crack w/ water when you're sponging. In any case, you shouldn't be grouting the floor-wall transition...you should be caulking it. Clean it out real good and dry it w/ compressed air or a good shopvac. Stuff backer rod in if it's deep and use a good polyurethane caulk (tool w/ mineral spirits). High quality silicone sealant is fine too, but it tends to get filthy here and is hard to clean.
> you shouldn't be grouting the floor-wall transition...
> you should be caulking it.Oh, I didn't know that. Good thing you saw my questions! Thanks.Janet
I couldn't find polyurethane caulk at the local Ace Hardware. Is this something usually purchased by builders? What brand do you use?Janet
Home Depot and Lowes carry colored caulk in the tile dept that matches many of their grout colors. A real tile store will carry caulk in every matching color."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
What is the secret to applying caulk? My caulking is a mess.Frustratedly yours,Janet
Put it on as smoothly as possible the first time. Don't wait until it starts to skin over. Don't try to apply cault to more than about 5 lf before tooling. Tool it with something ... a finger, a spoon, or heaven forbid a real caulk tooling dealie (looks exactly like a Wilton cake decorating knife) .. and be sure to lube the tool with water for latex or solvent for silicone."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Is the gap supposed to be slightly OVER-filled with caulk? I.e., in the attached drawing, is A better than B?Janet
A is exagerated, but that is what I would try for, more so than B."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
>What is the secret to applying caulk? My caulking is a mess.I like to first shoot all of the caulk in the tube into an old sweat sock. Then I use the sock as a grout bag of sorts to force the caulk into the cracks. The sweat somehow modulates the caulk and keeps it friable. I use the palm of my hand, or some other piece of silverware to 'smooth it'. Spit or brown shoe-polish works best for this part of the job. Also, you should know that old tubes of polyseamseal are the best. The older the better.Clean up any excess with Pam and toilet paper.Good luck.
I'm very interested in what you say about the silicon caulk getting fithy, as I have this same problem. It draws dust and hair from everywhere in the house!I can't believe I never thought to try a different material - duh! - I gotta think more outside-the-boxI'll look today for some poly caulk - are there any flavors you like for a simple white?Thanks!
Edited 6/3/2007 8:44 am ET by JasonD
I use PL cuz its all I can get around here.The stuff is messy though. Use the full masking method and tool w/ mineral spirits on a (gloved) finger..then pull the tape.
A large section for grout as you put it......needs "sanded" grout and the more water you add the weaker it will become as well as dry uneven in color.
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My first question would be:
What are you using for grout?
Are you mixing "dry powder" grout with water, or are you using a "premixed" grout that comes in a resealable plastic tub?
Is there any plumbing in the wall above the floor area where you're having trouble? Could be that someone nicked a pipe with a nail or screw and you have a slow drip.
Also, if you end up caulking, for filling deep gaps use backer rod in the gap prior to caulking.
Mongo
My caulking secret is to mask both sides of the joint, leaving about 1/16" of the surface visible. Use a backer rod if the gap is large enough. I find backer rod @ Lowe's in the weatherstriping area. Caulk supposedly can flex better if it only has two points of contact. Hence the backer rod. I then fill the gap with plenty of caulk. I keep a paper towel on hand, and wipe the grout smooth to the desired level (wiping my finger off on the paper towel when there is excess grout) and then remove the masking tape. Smooth the caulk one last time w/ my finger and I'm done.
A perfect caulk line every time!
Ott
A bucket and a sponge is better than a paper towel, and it gives you something to wet your finger.
Bryan,I certianly agree, but lots of times I'm using silicone. Which isn't very sponge friendly.Ott
For silicon I found that those blue shop towels (the paper ones in a roll) work pretty well, with mineral spirits.
I used to use the blue towels as well, now I just buy the box of 300 towels available @ Lowe's. They seem to be everybit as tough as the blue towels and I don't lose track of the box like I used to lose the rolls.Ott
Should I use caulk instead of grout in the vertical corner where tiles walls meet?-------Ott,Thanks for tip about masking tape. It looks much better now. I also used an ice cube to smooth the caulk. Don't know if that's better, but cleanup is certainly easier.Janet
Yes, because you are dealing with two different planes."Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt