restoring/replacing grout to a white state

[Adam Funk]

The extractor fan installed last summer is doing a great job of removing humidity from the bathroom, so none of the grunge is getting any worse. I'm convinced that if I could get the bath/shower grout back to a white state, I could keep it that way without much work. But getting it back to white is the problem.

Applying thick bleach with a paintbrush, normal bleach with a sprayer, or normal bleach with a rag, & rinsing it off later: mainly whitens the tiles, increasing the contrast.

Baking soda or washing soda, and a scrubbing sponge: no significant improvement.

"Bon Ami" scouring powder and a sponge: slow improvement but very labour-intensive & hurts my wrist (tendonitis).

Spraying distilled vinegar & leaving it to evaporate: no significant improvement.

I tested several attachments for my rotary tool (Dremel knock-off) on a spare piece of tile. The ones that didn't scratch the tile also wouldn't do anything to the grout.

I'm willing to skim the top layer of grout off and replace it --- is there a not too difficult way to do that? Any other suggestions?

Thanks, Adam

[Tjoepstil]

odd. generally chlorine bleach or caustic soda does te trick

try brick acid, rubber gloves and a nailbrush or scrubbing brush

[Martin Brown]

I have used a tungsten carbide bit intended for drilling through tiles as a way of cleaning off the top layer of grout and then added grout reviver for a quick cosmetic improvement of ancient mangy grout.

Any that falls out as a result of being stressed needed replacement.

It is pretty tedious but you can do a decent area focussing on horizontals first and then the verticals. Getting the angle just right is key. And you need a decent grade of tungsten carbide - one cheap and nasty one left dark residues but the real McCoy will cut clean.

Needs a fairly steady hand as the tool will scratch ceramic tiles if you slip.

[RJH]

Tissue soaked in bleach pressed against the grouted areas, then covered in cling film. Leave for 24 hours. Anything that survives that deserves to live.

[Adam Funk]

I haven't tried caustic soda yet, but now that you mention it, I have some in stock, so that'll be the next thing.

I was going to ask if you could still buy that without jumping through a lot of hoops, but I see that various DIY/building merchants' websites have it.

[John Rumm]

Rake out (at least some of) the grout and re-grout it...

Carbide/diamond segment saw on a multimaster type of tool does this easily enough.

About 3/4 of the way down this page:

Or something like:

[tabbypurr]

You're wasting your time trying to clean it unless it's fairly new. Scrape the top off & regrout.

NT

[Peter Parry]

Hydrochloric Acid (brick acid) undiluted will instantly and irrevocably mark many kitchen work surface materials as well as permanently marking stainless steel.

[The Natural Philosopher]

thats what brick acid does. turns the top layer to soluble calcium chloride.

Which can be washed off.

[The Natural Philosopher]

We are talking about a tiled wall dear. Now go back to sleep.

[Roger Hayter]

My tiled walls have s/s coving at the bottom, so I am very glad of the timely warning.

[PeterC]

My bath is old enamel and the trap is chrome plated brass - HCl just loves chromium!

[Adam Funk]

Actually that's relevant information. The walls are ceramic tile with grout, the bath is enamelled steel, but the fittings (shower-bath mixer attached through the bath tap holes, with a flexible hose up to a movable shower head) are chrome-plated, & there's a chrome-plated or stainless shampoo shelf (which I could unscrew & move out temporarily) in one corner. The plug-hole fitting may also be chrome-plated (I'll take a close look in a bit). So I guess I need to be careful not to let it touch any of the metal stuff, & find an alternative (more labour-intensive) way to clean in their vicinity?

[Adam Funk]

I've already got the tool and that kind of blade (from an Aldi set). How hard is it to rake off some grout without damaging the tile?

(I suppose I could practice on the tiled back of the cupboard under the sink, most of which is covered by stuff stored in there.)

[Adam Funk]

I'm afraid I'd klutz that up! I think John Rumm's suggestion sounds like something I could control more steadily.

[tabbypurr]

easy & fairly quick with a hand grout rake. Power tools are much more able to damage tiles, which slows down their use.

NT

[Roger Hayter]

I'm born clumsy, but I've managed to do it with minimal scratches on the tile faces although the tool was an interference fit in some of the grout lines. So it can be done, but you have to take it slowly and an oscillating tool with variable speed is essential. Slow rather than difficult. The grout is much softer than my (porcelain) tiles.

[John Rumm]

As long as the blade is narrower than the gap between the tiles, then there is no real problem IME. Keep the blade perpendicular to the tile, and don't apply to much force.

Unlike a manual rake, if you do cut into the edge of a tile, it will be left polished smooth rather than scratched (much as a rotary diamond tile saw leave nice polished edges)

Indeed, get the practice done on the bits that don't show ;-)

[Adam Funk]

OK, you've convinced me to try it.

That's good advice for almost any DIY.

[Adam Funk]

Thanks for the advice. I'm seeing progress, but it's slow work because too much DIY with wrist action (not for fnarring) can make tendonitis flare up, but faster than doing it all without power (although I did get a little grout rake for some spots).

One good thing I noticed is that if I slip out of place a little, the combination of tool & blade I'm using won't scratch the tile surface if I'm not applying much pressure.