Toilet limescale

July 21, 2006 9:51 AM

How do I remove 4 years of monster London limescale from my toilet?

My toilet has probably never been cleaned properly in at least the last 4 years, so it has a 2-3 mm coating of hard limescale all over the bowl below waterline. I've tried supermarket cola, which did nothing. I've tried going at it with a metallic scourer, which broke off some bits, but not a significant amount. What's next?

(I'm moving out and knowing my letting agents they'll charge me for a new toilet if I don't sort this out)

posted by cillit bang to home & garden (24 comments total)

Soak rags in vinegar, then place them on the scaly surface and let them sit for about 30 minutes. This will soften the scale and make it easier to scrub off.
posted by mbrubeck at 9:53 AM on July 21, 2006

You should dump in a gallon or few liters of white vinegar and let sit for two or three hours (or over night). Even better would be to turn the water off to the toliet, usually there is a off faucet somewhere on the supply line, and then flush the toilet so that the bowl is empty. Then fill it with vinegar. It should dissolve that limescale straight away.
posted by sulaine at 9:57 AM on July 21, 2006

Instead of these folky remedies, have you tried actual limescale remover? It's always worked well for me.
posted by reklaw at 9:58 AM on July 21, 2006

Is CLR available in the UK? That stuff RULES for limescale.
posted by deadmessenger at 10:01 AM on July 21, 2006

Vinegar is cheaper and works many times better and faster than any commercial limescale remover.
posted by sulaine at 10:01 AM on July 21, 2006

You want an acidic cleanser for limescale. For the simple approach you could try distilled white vinegar and a lot of elbow grease, I've also seen hydrogen peroxide suggested, but I don't know about a buildup of the magnitude you describe. There are a lot of commercial preparations like CLR - which probably include some added components, maybe detergents and chelating agents, to help dissolve the minerals and keep them in solution, and shopping for these might be the best bet (I don't know if the brands are the same in the UK but it's a pretty common cleanser variety). Again, given the depth of the deposit (3 mm? Damn) whatever the case I think hard scrubbing and multiple applications are going to be required. In future, a moderate program of routine toilet maintenance might be in order. Ick.
posted by nanojath at 10:02 AM on July 21, 2006

A flat landlady I knew used to swear by using a full bottle of bleach -- specifically Domestos.

The acid ideas should work -- e.g. vinegar or citric acid.
posted by Idcoytco at 10:05 AM on July 21, 2006

A gallon vinegar costs about 99 cents (USD). A gallon of chemical-whatever will costs many times that. And vinegar is a highly effective cleaner. So use the vinegar first to remove as much scale as possible.

Trisodium phosphate (in the US, you can get it at hardware stores) is also quite effective, though you have to be more careful handling it than the vinegar.

For truly stubborn, thick scale, I find that a pumice scrubbing stone (about $5USD) works wonders. But despite the claims, it is possible to scratch porcelain this way. So once you've used the pumice to chip away the majority of the scale as large pieces, switch to something gentler (Barkeepers Friend?) for making direct contact with the porcelain.
posted by nakedcodemonkey at 10:12 AM on July 21, 2006

Soak overnight with Coke or Pepsi (in the page, the suggestion comes from a Londoner). The phosphoric acid loosens it up.
posted by plinth at 10:13 AM on July 21, 2006

Acid of course is what is needed, but you need something much stronger than vinegar. The professional approach to this is to use a solution of hydrochloric acid - usually in the form of some commercial preparation like Kick or Zep.

The Kick that I used om my toilet for example, was 24% HCl
posted by Neiltupper at 10:15 AM on July 21, 2006

Have you tried the product that shares your (user)name?:

"Limescale, rust, ground-in dirt. The're a problem for some household cleaners, but not for Cillit Bang.
posted by Mayor Curley at 10:24 AM on July 21, 2006

For the 'below the waterline' stuff, Steradent. Otherwise, the best limescale remover I've ever used (it got rid of what looked like stalactites from inside a tea urn) is Kilrock, which you'll find in Robert Dyas or other places selling general hardware.
posted by essexjan at 10:33 AM on July 21, 2006

Seconding the hydrochloric acid recommendation - I've used it with great success. And it's fast.
posted by goo at 10:54 AM on July 21, 2006

There is very little phosphoric acid in Coke. There is a lot of carbonic acid - in fact, it's supersaturated. Carbonic acid does eat lime, but it goes out of solution very fast in atmosphere. (That's the Coke going flat, and it's the flaw in the methodology of Mythbusters' "test" of Coke dissolving a tooth. They left the Coke uncapped.)
posted by Kirth Gerson at 11:03 AM on July 21, 2006

Looks like we need the 'eponysterical' tag
posted by mbrubeck at 12:25 PM on July 21, 2006

I'm sure hydrochloric acid works well, but I don't like caustics which are that dangerous. I'd recommend acetic acid or citric acid first, and resort to the heavy artillery only if those fail.

Acetic acid (i.e. white vinegar) is cheap, plentiful, and very safe to use. It may not work, but it should be the first thing to try.

Comet makes a spray bathroom cleaner which is a 6% solution of citric acid. Also safe and likely effective, but much more expensive.

But all of these will require substantial soak time for scale that thick and hard.

I wouldn't think bleach or peroxide would be effective. Scale is carbonate, and I don't see the chemical reaction that would break it down. With an acid the reaction is obvious.
posted by Steven C. Den Beste at 1:26 PM on July 21, 2006

Yes, use a reducing acid like acetic, not an oxidizing acid like peroxide or perchlorate.

Vinegar's only about 0.5% acetic acid by weight, so a bowlful "poops out" pretty fast; if you can get it in a stronger concentration, you'll save labor.
posted by ikkyu2 at 1:36 PM on July 21, 2006

I also have the London creeping scale. I use 'spirit of salts' from a plumbers merchant which is hydrochloric acid and other things. Put it in, leave for 10 mins then scrub.
posted by lunkfish at 2:23 PM on July 21, 2006

With all due respect, both acids and peroxide are "oxidizing" agents. Lye and Potash are reducing agents, but they'd be completely useless here.

The reason an acid works on scale is because hydronium interacts with the carbonate in the scale, causing the acid to replace the carbonate. Calcium carbonate doesn't dissolve well in water, but calcium acetate does, and the carbonic acid fizzes away.

Bleach (hypochlorite) and peroxide do their magic by spontaneously creating oxygen radicals. For some kinds of chemical reactions there's nothing better, but I'll be damned if I can see what an oxygen radical would do to calcium carbonate. Interact with water and then form calcium hydroxide? That doesn't seem likely.
posted by Steven C. Den Beste at 2:53 PM on July 21, 2006

From previous experience with thick, encrusted limescale in a kettle, vinegar does very little, too weak for such a hardcore cleanup. The expensive over the counter limescale removers are probably going to be the only way. Instead of buying bottles and bottles of stuff to try and fill the toilet, or not get too diluted by the water, maybe there is a way to apply a kind of compress to the walls of the toilet?
posted by Joh at 3:10 PM on July 21, 2006

Spirits of salts, hydrochloric acid and muriatic acid are all the same thing. It will clear up your limescale, but it might also clear up your clothes, skin, eyes and/or lungs. Use with caution.
posted by flabdablet at 7:55 PM on July 21, 2006

Don't use your namesake product, whatever you do! It'll remove the limescale, but it will also completely strip the porcelain off your toilet.
posted by jack_mo at 7:19 AM on July 22, 2006

Previous thread
posted by amestoy at 3:33 AM on July 25, 2006

I got the Kilrock from Robert Dyas that essexjan mentioned. It took 2 goes overnight to get rid of all of it, but otherwise it worked brilliantly.
posted by cillit bang at 10:24 AM on August 4, 2006