Grout shading problems over Kerdi [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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11-25-2009, 07:28 PM
I have installed 11 kerdi stalls in the past 5 months, and have been having problems with quite a bit of shade variation in the grout on the walls. All were stuck with either Mapei/Kerabond - unmodified, or Hydroment/Ditra-Set. Tile used in all, while from different manufacturers, A.O. or Portinari, were all talc bodied (white) glazed ceramic. Grout used has been unsanded from the big four in my area (central Maryland), Tec,Mapei, Laticrete and Hydroment. Colors range from light(Mapei/straw) to dark (Hydroment/summer wheat). Blotching shows up within 24 hrs. Leaving the installation alone for 28 days, enough time for curing, does nothing to resolve the issue.So far the only thing that has worked ,has been to scratch out the darker joints and re-grout. Joints are clean prior to grouting. Blotching occurs in approx. 3% of the joints. Water used to mix/wash comes with me to the job from home, as it has for the last 26 years. Houses are new construction, with "good heat", (no salamanders or propane bottles) from the furnace. Shower floors are 2"x 2" w/sanded grout, no problem. Jacuzzi tubs over backerboard, no kerdi, are same wall tile/grout combo, no problem. Have been using the kerdi system for 5 years now, have approx. 50 installs, with only only occasional minor joint shading. Anybody else had this one? Any advice would be helpful. Thanks

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11-25-2009, 07:46 PM

I dont have the problem with what you are saying and have done a good amount of Kerdi showers.

you might want to try the Laticrete 1776 Addmix ( instead of water next time.

LATICRETE 1776 Grout Enhancer
Designed for use with LATICRETE 1500 Sanded Grout or LATICRETE 1600 Unsanded Grout. LATICRETE 1776 Grout Enhancer, when used in place of water, eliminates shading and blotching caused by minerals and organic particles commonly found in domestic water. Inhibits the growth of stain-causing mold and mildew in the grout joints with Microban antimicrobial product protection. ASTM C627 Rated “Extra Heavy” Service.

11-25-2009, 08:14 PM
are you using grey thin set with a light colored grout? Maybe or not the problem .

I have had better grouting exp. since changing to white a few years ago.

11-25-2009, 08:24 PM
Welcome, Steve. :)

How long do you normally wait after setting the tiles before you grout?

11-25-2009, 08:28 PM
First off I'm gonna suggest you try Laticretes' Permacolor grout, its nice grout especially in the color consistency dept. My first thought seeing you're using soft bodied absorbent tile is that the joints are setting up quickly on you and you are washing them aggressively thus washing some color outta the grout.

Shower floors are 2"x 2" w/sanded grout, no problem.
The floor tiles are probably denser,the joints easier to cut down, less washing, better color.

I know you are a pro but are you getting ahead of yourself spreading the grout? I use unsanded grout only when I have to,sanded being first choice.

I know sanded grout paired with a soft bodied tile, if timed just right, is gonna yield a dream come true grout job. :)