Any way to get grout residue off of hardwood?

December 30, 2010 8:10 PM

Any tips for getting grout residue off of hardwood floors? Some previous owners of my house had carpeting in the living room, and tiles that they placed around the fireplace hearth (tiles were 1/4" thick and brick-like, in case anyone cares). I removed the carpet and the tiles to reveal the hardwood floors underneath, which is in fairly good shape in most areas. Except right around the fireplace where some white residue remains from where the tiles were. Is there anyway to reduce or remove this completely other than refinishing? Or should I just put an area rug over it until that time comes?

Here is a pic of the living room before the carpet and tile were removed. This shows it after with the residue, and here is a zoomed in pic.

The house was built in 1925, and I'm assuming that the floors are probably original, but I could be wrong. I have no idea what kind of finish is on them right now. My aunt sent me a link telling me how to test for varnish and shellac, but when I did the test there was no flaking that would indicate that it had either of those things. Considering we found remnants of green shag around the fireplace and baseboards, I'm betting that the finish isn't modern polyurethane.

I am planning on refinishing eventually, but that may be a couple of years down the road and was hoping I could minimize the residue between now and then.

posted by weathergal to Home & Garden (9 answers total)

It's going to be difficult to get it all out; wood is porous, and it's had plenty of time to seep in. Plus, you may replace the grout with light scratches if you follow my method. I am assuming it is pretty flat on the surface. Any raised elements are a little easier to remove (I like dental picks, but a razor blade could get 3-D residue off).

I would start with a little water and a rough sponge (I use the forest green scotchbrite ones that are thin when I'm cleaning up after any grouting big or small, and have a rough and tough texture but don't have wiry or sharp fibers) for my initial attempts at grout spills and errors. I want the sponge to be damp for the first run, and a little wetter for the second. That will get the easiest residue off. This works much better for new grout than aged grout. The problem with this method is that areas that look cleaned when wet may ghost up again with residue when dry.

Then I'd go for a hardwood cleaner - a cleaner that is designed to work on wood floors. This will get up some more of the residue, and will do it in the most wood-friendly method.

If it was my floor, I'd then try a diluted vinegar wash and scrub (it counteracts the drying effects of concrete products, and might help loosen up some detritus), but I don't actually know what it would do to the floor itself (i.e. like maybe discoloring, ruining a finish)

If that doesn't work, I'd probably go with a rug (or carpet tiles) until I could do refinish in the future.
posted by julen at 9:00 PM on December 30, 2010

Is this grout or cement? This question from my husband, formerly a professional tile guy. At first he said to try vinegar and a green scrubby. But then he said you'll probably need to refinish.
posted by bluedaisy at 9:35 PM on December 30, 2010

Wood scraper a well prepared hand scraper a leaves a smooth finish that will not need sanding.
posted by hortense at 10:18 PM on December 30, 2010

If you do go the area rug, use a pure wool one. It would be a shame to burn your house down with a stray spark before you can refinish the floor.

Also, if you've managed to scrub most of it off but you still end up with grout ghosts that you can see but not feel, try a light rub-over with an oily polish before ripping up the old finish and starting again.
posted by flabdablet at 1:45 AM on December 31, 2010

You have two options -- mechanical and chemical. Mechanical methods such as scraping and sanding would undoubtedly damage the finish, because you'd be pushing around little particles of rock which are harder than the finish and harder than the wood, using tools that are also harder than the finish and wood. Chemical methods might damage the finish, but might not.

Portland cement, which is the binder in grout and cement products, is alkaline, and is broken down by acids. Vinegar is a common household acid and worth a shot, but probably won't be strong enough to solve your problem. If you go to the flooring section of your local Lowes / Home Despot, you'll find small jugs of a stronger acid solution called "grout haze remover." Follow safety precautions (gloves, safety goggles) while working with the stuff. The process will be something like: apply acid, wait, wipe up with damp sponge, repeat.

Like I said, this may damage the finish. But it's worth a shot.
posted by jon1270 at 2:07 AM on December 31, 2010

That's not grout, it's "thinset". Thinset is the "cement" that tilers put down and squish the tiles into. Grout goes between the tiles, once the thinset has dried and the tiles are locked into place.

That being said, I don't know if thinset has a solvent, and I would guess that it does not. You're probably going to need to have your floors sanded and refinished, which will probably cost you somewhere around $2.00 per squarefoot, depending on your location.
posted by Glendale at 6:58 AM on December 31, 2010

If your house was built in 1925, the thinset may contain asbestos. If that's the case, sanding it would be a bad thing.

There are solvents, but I had similar thinset that was untouched by the citrus solvents. I ended up cutting out the wood and replacing it with marble because it was water-damaged in spots anyhow, and removing it entirely was safer than screwing with it.
posted by DaveP at 11:14 AM on December 31, 2010

That's not grout, it's "thinset". Thinset is the "cement" that tilers put down and squish the tiles into. Grout goes between the tiles

Yes, but with the exception of unusual and expensive epoxy grouts, the chemistry of grout and thinset cement is very similar. Acid is the way to loosen either.
posted by jon1270 at 11:39 AM on December 31, 2010

Thanks for all the hints guys! Whatever this stuff is grout/cement/thinset, any suggestions for what to try were welcome.

flabdablet, unless I lose power and have to use the fireplace as a backup heat source, I'm not planning on building any fires at least this year until I can get a glass door installed (when reading this thread I found out that building a fire can actually cool down the rest of the house, and I'm in North Dakota and don't really want that). If I do end up using it I can pull or roll the rug away from the fire.

DaveP, I don't think the thinset has asbestos, since the tiles were not original to the house. We found the green shag carpet remnants right up against the fireplace stones, so the tiles were probably installed at the same time as the white carpet in the first pic, maybe 80s or 90s.

I'll probably try a household vinegar solution/scrubbing first, then the stuff that jon1270 mentioned. Thanks again everyone!
posted by weathergal at 1:51 PM on December 31, 2010