How grout mosaic tiles (Glass and Slate) [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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03-04-2007, 08:03 PM
Hello --

I have to two types of 1x1 mosaic tiles. One is glass, the other is slate. I'm using them as borders around a recessed shelf and shower. I grouted the shower using sanded grout (from MAPEI). My questions:

1. Should I use the same grout for the mosaic tiles?
2. Would the sanded grout scratch the glass tiles?
3. Should I preseal the slate mosaics before grouting?
4. Should I use the bag technique or the rubber float?

Any other tips?


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03-04-2007, 08:09 PM
Hi Sam, you can use the sanded grout. You can preseal the slate before hand. You'll be fine with a float.

03-04-2007, 08:13 PM
What is the surface like on those glass mosaics? Are they really smooth, or is there a bit of a texture? If there's texture, I wouldn't worry too much about scratching them (glass is pretty hard).

Use a rubber float. A bag would take forever.

03-05-2007, 11:42 AM
The glass is smooth. Should I worry?

Another related question is what the best consistency of grout? The problem I was having with the wall was I would put the grout on my edge of my float and then apply it over the tiles. The grout would fall off the wall (making a mess). I tried making a thicker batch of grout and I had the same problem.

Can someone tell me how thick the grout should be? And how to apply the grout on the wall and how to effectively use the rubber float? It took me forever to grout the shower walls and I have more grout too.

Also, typically how long would a 50sqft area take to grout?

Lots of questions I know!


03-05-2007, 01:28 PM
as a DIY it is a little messy to grout walls,but hey it has to be done,(Gravity is the culprit here)It should be mixed to the consistancy of icing,not runny and not crumbly,usualy the directions on the bag are close ,I know we DIY never mix a whole bag at once,just mix each batch the same,I use a combination of a good quality grout float and a plastic 4 to 6" spreader in combination with each other I will spread some grout with the spreader holding the float against the wall angled up,this catches any that may fall and then I use the grout float first gently to spread it and fill the lines then as usual to pack it in,this has worked well for me with a min. of mess,using the spreader to catch the grout when floating .of course i have only done a fireplace and a couple of backsplashes,and wet bar that was verticle,have a great day

03-09-2007, 09:49 AM
Great info...

Here are my problems:
After the grout hardened... I noticed the grout lines weren't clean (i.e. smooth). Can I grout over them again filling in any holes/bumps? Or do I need to remove the grout first?


03-09-2007, 09:59 AM
Unless you're using an epoxy grout like SpectraLOCK, you can't really grout over grout with any success. You will need to remove most of the grout in order to properly re-grout.

How bad is it? Can we see a picture? I know that I tend to be hypercritical when I'm in the midst of a project, often fretting about things that will largely go unnoticed later.

If you do decide to repair it, try this next time. Set a small amount of grout aside. On your first cleaning, if you notice a hole or a low spot, you can repair it then before the grout sets up if you are careful.

03-09-2007, 10:20 AM

Also, typically how long would a 50sqft area take to grout?

Depends....... :( You have a 1x1 mosaic - lot more grout lines to look at..

I'm gonna go with 2 hours here - start to finish...

Any other guesses out there in Tile Cyber Space? :D

03-09-2007, 02:48 PM
I can be pretty anal... from far you can't tell but if your close (like taking a shower) you would notice certain grout lines have "bumps" and thats annoying the heck out of me.

Another Question:

Whats the best way to remove dried grout from glazed porcelain tiles?



03-09-2007, 06:51 PM
Best way is to do it while you're cleaning the grout.. Second best way is with a scotchBrite or similar pad that is not really abrasive with a little water.. Soon.. :D

03-10-2007, 02:48 AM

LOL I thought I was! But the slate tiles even after applying the seal still has grout stuck on it. I cleaned a good part of it but theres a still plenty that needs to be removed which isn't coming off with water and scrubbing.

Some thoughts...

1. Sanding the grout off...
2. Acid? But I wasn't sure what sorta acid I should use.


Thanks again,

03-10-2007, 08:52 PM
Sam, you might try some vinegar. rinse it well with water afterward. Find a wood towel that's the size of a pencil and sharpen it. You can dig at the grout on the tile surface without hurting anything.

From now on, wash the slate first, it's gonna set on the surface faster than other tiles. Of course you know that now. :)