This is really off topic, but I thought since several people here are experienced with grout and paints ect, this would be the place to ask. I have searched around on google but didn't find anything really to answer my questions.
We just laid brand new tile in our bathroom and grouted it. I am pleased with how the project turned out overall. Very unpleased with the color of the grout. It is much lighter than the color sample and really just turned out a gray color-should have been a deeper taupe color with a green hue. I would like to change the color of the grout. I found a product made just for this, but they don't have a color available that matches my tile right. After reading through dozens of reviews on several sites, I am inclined to believe this grout 'stain' as it is called, is nothing more than glorified paint. By glorified, I mean it contains mold inhibitors and something to prevent fading of color from UV rays. I found a bottle of it at the local Habitat for Humanity store and read on the label. It is water clean up and dries quickly. I opened the bottle and smelled it and it really did not have any odor. SO. My question is, do you think it would be ok to use a high quality flat finish exterior paint to color my grout lines? I am thinking that would also have the UV protection and the mold inhibitor (which I don't think is necessary unless you were using it IN a shower anyway?). I was thinking of slightly thinning it with water so the pigment would color the grout but would also be absorbed by the grout, not just sit on top like a layer. I plan on using a small art brush to apply it. After this all dries for a day or two, I'd like to seal the grout lines with a regular tile sealer. If I botch this up my husband will KILL me! And this same tile is going to go through the ENTIRE house-one room at a time in a slow motion DIY fashion! I covet any advice.

I don't have an answer for you but I'll send Becky a link to this. She is a very talented and gifted artist and has painted many things but not sure if that includes grout. We'll ask her though, huh?

You might ask Gordon, he does so many different projects on houses, he might have an idea.

Well, I hope I can help.

The first thing I would do is test some behind the potty, okay?

BUY patio paint from Hobby Lobby, Michaels, or JoAnns. It's an acrylic made for outdoor use and so it should hold up great. Exterior Flat will also work.

Use it watered down just like you thought....good thinking!!! But test it behind the potty. After a couple of days, pretend you're going to mop the floor and make sure it doesn't all come off!!! It shouldn't.

I hope this helps!

Thank you, I will check out Hobby Lobby-I didn't think of that!
And also didn't think of the washing thing either!

Thank you Becky - I knew you would know what to do

my pleasure!

If you haven't sealed the grout yet, you could wet and only towel dry the tiled area leaving the grout dampened again, and then take any latex paint color you like and a small brush and create the effect.

The secret is to SUPER thin the color to make it more like a water color wash and clean wipe the tile edges as you go. Let the color soak into the water based grout until you achieve the desired hue and let dry for a few days. This is when you would want to re-clean the floor and add a grout sealer.

Great input David!!

well unfortunatly I do have some grout painting experience..first I'd want to know if the grout was a sanded grout or not... as it is a floor does it have a wide grout line or thin... like 1/8 " or so...wider lines are often sanded grout... and the size of the tile...to figure if it would be too much work..sounds like biggger tile though..
taking out the grout isn't all that hard ...a diamond blade in an angle grinder or roto-zip makes short work of it.. I recently used it to channel out some 1/2"grout lines line to run a water line to a refrigerator across a kitchen.. where they had a lovely big sub zero unit.. but no way of getting water it over to it... in an all concrete building.. with a passage way on each side... they had it like that for years as noone could help them.. one line of grout took 5 minutes to clear..digging through to the slab and then 1/4 ' into it..I ran the 3/8 " water line then regrouped.. for your regrouting just going 1/8 " through the old grout would be plenty to get a new grout surface to stick into...
as far as painting.. I laid a rubble granite floor here at home out of 3/4 to 1 1/4 " hunks of stone.. so it was deep and wide.. and needed a sanded grout..so I thought I'd use some.. but the color wasn't dark enough.. so I repainted with an thined out oil paint.. it wipped off the tile easily.. with thinner and hung into the grout fine for the last 20 years.. the grout will stain but you do need a binder in the pigment to get it to stay in there through washing and use..
often in cleaning up the origional grout they hhave left a slight sub surface radius.. you could try floating a tiny bit of a grout with an epoyx to just top this off...Lowes sells the epoxy kit for thheir grout.. but you can use it instead of water with any grout.. clean up quickly per instructions with vinigar/water... as it in the tinyest of amounts will stick to anything... almost forever...
have you got a close up picture of the grout line you have.. and one of the floor?

I am just doing ceramic 12x12 tiles and sanded grout with 1/8th inch lines. I bought a latex exterior paint and just used a small brush and just painted the grout. It wicked up almost instantly and wasn't excess wipe off. That was yesterday. I only did half of the bathroom floor because it is slow tedious work! Hope to finish the rest later today. I ordered some water based 20 yr grout sealer and will seal over the grout lines with that. I figure if there are areas that need touching up from time to time, a weekend will do it every few years and the paint is cheap, so I think I will be pleased with it.

Gordon your floor looks really shiny, how did you manage to use a sanded grout and not scratch it? We laid a shiny porcelain tile in the shower and used unsanded grout there with 1/8th inch lines. I love the really shiny tile in a shower.

it's a high polished granite to start with..
I got the stone over the fence where they had dumped it.. from hhaving cut thhe nice counters out of the center of the slabs.. and have had ten for twenty years as a floor.. yes they are compleatly withhout scratching... it's some hard stuff.. and all of it a bit different..from type to type
your project seems to have gone on real well... congratulations... good work guys

That floor is beautiful Gordon

I will post pics of mine later when I am done. Thanks guys for your advice, I appreciate it!

Gordon, that is a gorgeous floor!!