grout color problems

[steve_j]

I finished grouting the ceiling, walls, and floor of a mortar bed shower several weeks ago. The grout lines on the horizontal surfaces of shelves in the shower had some efflorescence on the grout so I decided to use sulfamic acid and clean the whole shower thinking I would avoid any possibility of color variation by doing so. However, after the thorough cleaning and a very thorough immediate garden hose rinsing I have some troubling color variations in the wall and floor grout that did not exist before the acid wash and rinse. The ceiling and wall grout is custom building products sanded "light smoke" and the floor is custom building products un-sanded "haystack".

The color variation in the floor grout is localized and initially I thought it was moisture as it is the same color as when the grout is wet/saturated. But as of today it has been a week from the water deluge so it should have dried out by now. I held a hair dryer to the area for a while to check for moisture-no luck.
The color variation in the wall grout is primarily in the horizontal grout lines and looks like water drop stains. Where did I go wrong and how can I fix this problem before sealing the grout?

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[John Bridge]

Hi Steve,

Acid cleaning requires scrubbing of the surface, either with a stiff brush or some other agitator. You can't just put the acid on and rinse it off. I suspect you still have some deposits on the surface of the joints and that this is causing your color variations.

I'm going to move us to the cleaning and restoration forum. :)

[steve_j]

John, thanks for the reply and moving the post to the proper location. I failed to mention in the initial post that I used one of the blue tile scrubbing pads to go over the tile and I used a scrub brush on the grout lines with the acid. I have a few pictures but I couldn't figured out how to include them with this post. I'll post them when I figure it out.

[steve_j]

Following is a link to a picture of the floor. If this works I'll do the same for the other two pictures.

http://www2.freepichosting.com/Images/31751/3.jpg

[steve_j]

Here is the other floor picture and the wall picture.

http://www2.freepichosting.com/Images/31751/4.jpg
http://www2.freepichosting.com/Images/31751/5.jpg

[doitright]

Hi Steve, Welcome :)

Thanks for the pics. It looks like acid burn to me. It's usually caused by not prewetting the grout joints sufficiently, and having to work on a vertical surface (concentrated rundown). :(

The best solution I know is to use Aqua Mix grout colorant. I would try to blend the area 1st, and see how good the colors come together, then you might get away with sealing the rest of the joints. Otherwise you'll have to do at least the whole floor and the whole wall where the problem exists. The only other way is to remove the grout and regrout the bad areas.

[John Bridge]

For some reason I can't bring up the pictures.

[kemguru]

Hi Steve :)

No pics here, too :(

Is the color (discoloration) the same through the joint? You can scratch a little discolored are to see if it goes deeper.

If not…

Another acid wash may clear it up. You would need to use Phosphoric or one of the new hybrids, such as TYW Tile & Grout Restorer. These are stronger than Sulfamic, but if you pre-wet the surface and scrub with a nylon brush, it might work. If you rinsed the Sulfamic off as fast as you claim, and it is acid burned, the burn should be topical.

If all else fails, follow John K’s advice. You could recolor (stain or seal) the wall joints, but NOT the FLOOR JOINTS. Stain/colorant will seal the floor joints too well, drastically decreasing the vapor transmission properties of the grout. Water will find its way under your tile, so it needs to find its way out. ;)

[steve_j]

John K. - Thanks for the reply. I'll look into the Aqua Mix fix. It sounds like it'll probably work weel on the walls since the color variation isn't as extreme as the floor. Acid burn never ocurred to me. I guess I assumed the whole idea behind using sulfamic acid was that it was a mild acid solution and couldn't become too concentrated since only so many crystals dissolve in water. FWIW I followed the sulfamic acid directions to the letter. Soaked the entire shower for a good hour before application and thoroughly rinsed immediately after I finished a wall. The floor in particular received the best soak and rinse since it collected and drained all the water.

John B. I'll try to take some more pictures at a lower resolution so that I can use the browse attachment feature instead of links. The links worked fine yesterday, but they don't work for me either this morning.

[kemguru]

Well…

I don’t think its acid burn, but I haven’t seen the pics. ;)

Sounds like you did just fine. Sulfamic is pretty weak, but it’s still a possibility, especially with certain colors of grout.

So you used a lot of water, eh? Could it be moisture under the joints? Are the discolored areas getting lighter with time?

[doitright]

Hi Tim :)

Thanks for the save! I forgot this was a shower floor. When you see the pictures, you'll see the situation. I've dealt with this problem before with my helpers (when left alone too long :D ).

I don't think any further cleaning, with any type chemical will help this matter. There I go thinking again, I could be wrong! :fim:

[steve_j]

Here is a picture of the floor-resized and saved with a lower resolution.

[steve_j]

Here is the wall.

[steve_j]

I scratched at the joints and the good new is the discoloration on the walls is skin deep and can be cured with a little elbow grease and a rough towel or rag. The problem areas on the floor are a little more than skin deep but definitely not through the joint. Should I just scratch through the discolored areas or is completely removing the grout and then re-grouting the best way to go?

[John Bridge]

Steve,

I can see on the walls that the acid solution dribbled down and left its trail though the horizontal grout joints. That's just a matter of better contolling your process. Start at the top, of course, and work your way down, rinsing and cleaning up as you go.

The floor grout appears to have drawn bad stuff from the mortar below. I would scratch those joints out and re-grout them. :)