Need advice for inconsistent grout color

[Wakesurfer]

I am FINALLY in the grouting phase of my garage tile floor project. The whole garage is primarily grey, including the tile, so we decided to use a blue grout to add some color. The grout is C-Cure #86 ("Ocean Blue"). It's a medium blue sanded grout (3/8" joints). Here is the problem:

We have been doing 1/2-2/3 of a 25# bag at a time to keep the work manageable. We are mixing the grout using a sealant (replaces water in mix) recommended by our supplier. We noticed some color variations between the 3 batches we have done so far. The batches have gotten darker! At first I thought it was the difference in cure times and we just needed to let the grout dry completely. However, if I scratched the top surface of the most recent (darkest) area, the underlying grout is much lighter and almost a perfect match to the light areas. It seems as though a thin layer of pigment leached to the top during the cure! Unfortunately, any method I have tried to remove the layer has resulted in too much material removal and too rough of a surface. I will have to regroup those areas! :-( Here are my questions:

1). Did I fail to be aggressive enough with my sponge cleaning of the grout joints? Did this lead to a thin layer of pigment leaching to the top?
2) The only thing that was different between batches was that I let the 3rd (darkest) set a bit longer than the earlier two before sponge cleaning. I did this because it seemed to allow me to be more aggressive with cleaning without risking removing too much material.
3) What tips do the GJ Pros have for removing (sponge cleaning) the grout from the tile? I have done tile before and read/watched dozens of books and videos, but I've never worked with a grout colored like this!
Thanks!

 

[duneslider]

Its hard to say what exactly is going on but it is always tricky mixing partial bags at a time. The grout itself needs to be mixed dry first to make sure the pigments are distributed evenly, it can settle in the bag.

You didn't wash to aggressively though, too much washing will lead to lighter colors, or you did wash the first ones too much and the later ones not as much. I have found extreme colors like red, blue, etc to be more difficult. It takes a lot of pigment to get those colors.

I wash with sponges and usually follow up with a quick drag with a microfiber towel, that picks up the haze really good.

You might need an acid wash to help even out the grout colors. A call to C-cure might help too. I am not too familiar with that brand and what they would recommend.

 

[rsanter]

When done, paint or stain the grout with the stuff used to recolor exsisting grout.
It will also act to seal the grout

Bob

 

[duneslider]

Does it all look the same color when you get it wet? Typically, inconsistent grout color is a direct result of poor washing technique. Some grout brands are worse at this than others. It can also depend on how wet the mix was when mixed, and how quickly the substrate pulled the moisture out of the grout. I have stopped using "standard" grouts because of inconsistent results. There are better grouts out that prevent coloring issues.

I would look at grout staining as a last option. It is not the easiest to put on and is more expensive than other options.

If it is consistent color when wet you have a good chance that an acid wash will make it consistent. See what C-cure recommends. I usually started with a vinegar/water mix.

Or you can seal it with a color enhancing sealer and that will make it look darker like it does when it is wet.

 

[Wakesurfer]

Thanks for the advice everyone. Yes, the color is consistent when wet and the area underneath the very thin top layer is consistent (lighter blue). I used a grout removal tool to clean out the darker areas so I can re-grout, and the layers below the top all match very well! I'm guessing it is my washing technique/timing that is the problem. I'll call C-Cure to check, because this color is specifically listed as one not to acid wash/clean.

 

[Wakesurfer]

***Update:***

After a lot of research and work, the main culprit was...surprise, surprise... our technique! The lighter areas were where we did too large of an area and more sponge cleaning was required. This caused more efflorescence in those areas. The fix was to use an acid wash (as recommended by the manufacturer, contrary to the labeling!). This really helped smooth out the color gradients.

A word of caution, mix the acid wash to a very mild mixture. Initially, we were too aggressive and actually caused one area to discolor. We had to remove the grout and re-grout a section. That process totally sucked!

 

[duneslider]

I doubt it was efflorescence but regardless I am glad you were able to get the results you hoped for. Now get it sealed before it gets messed up!

Over washing is one of the biggest mistakes made with grout. The second is improper mixing. Both can cause the coloring issue and both are easy to do wrong.

 

[Wakesurfer]

Hopefully sealing this weekend!