Heavy Duty Descaler

Pretty feeble but cheaper - combined with table salt it might be OK.

White vinegar and table salt would make a bit more sense. That generates a trace of hydrochloric acid which is a much more active descaler.

You probably want to use hydrochloric acid (aka brick acid) though to remove bad limescale. It might attack the glaze if left in too long.

This looks about the best buy on Amazon to me:

Under no circumstances combine it with bleach or you will be choked by chlorine gas!

I use spirits of salts, which is strong hydrochloric acid. It has to be handled with care and gives off choking fumes, so is best poured while wearing a suitable, preferably full face, respirator. Never found anything to beat it for removing scale though.

Citric acid is a less powerful version of hydrochloric, but minimal safety issues (you can buy it food grade that's safe to eat, I usually get 1kg bags) and it comes in anhydrous granule form. I normally mix up a saturated solution in hot water or sometimes pour the granules onto a wet surface. It can need a little scrubbing at times though.

Theo

Maybe one of the HG products

I though white vinegar and baking powder was meant to be the solution for a blocked sink waste????

patio acid, rubber gloves and a club hammer and cold chisel. The problem is that the acid gets neutralised at the surface, but breaking off the surface speeds everything up. Takes a day or so to clean

If it is a difficult problem to make go away, replace the toilet... Not that expensive and can be a fairly quick and easy job.

Domestos sell a "Zero Limescale" toilet cleaner which contains hydrochloric acid and is highly effective. Use it a few times instead of a regular bleach cleaner.

I bought a gallon of Red Phosphoric acid with a nice smell off Amazon for £15. It does the job well.

Also good for removing rust.

IME while the supermarket products work they tend to err on the side of safety which reduces their effectiveness - what's needed is strong acid. I used to use brick acid (AKA muriatic acid, hydrochloric acid, often with an added surfactant) but recently I got some anhydrous citric acid that works pretty well and is less hazardous to use. With the brick acid for heavy deposits I used to drain the U-bend and apply it neat, with the citric acid I can just tip in some of the crystals. With either you'll get faster results if you scrub the surface periodically to allow the acid to penetrate, the usual caution to use skin and eye protection obviously applies.

Where did you see that? It's more-or-less chemically impossible to generate a stronger acid from a weaker one in an aqueous solution.

Have you got a ref for that? From what i understand, porcelain is a vitreous aluminosilicate. It can be attacked over time with strong alkalis, but acids do not affect it (other than HF, which is a very special case).

That's a good general rule in case you have some conc sulphuric acid to dilute, but with other acids it really makes no difference.

Indeed. Do it all outside or be prepared to flush the loo pretty quickly!

Aside: hydrochloric acid and many strong descalers discolour Chrome: Do not use on taps

DAMHIKT

Many thanks for all the replies :-)

I found HG de-greaser excellent for the kitchen when I first moved here so I will give the HG gel a try, I'll move on to successively more powerful (and lethal) stuff if necessary.

Just to say I remember the point about adding acid to water and nit vice versa from chemistry lessons 60 years ago, we were told always add the strong to the weak.

Stops it from boiling off and splashing.

Yes but but but: the fumes can cause iron to rust, chrome to be stripped, etc. And because it's fumes, pouring gently and accurately isn't enough, they *will* spread.

Not saying you are wrong, mind you, just that it really does need care, and not just for personal health and safety. It will eat away limescale in minutes that days of vinegar won't strip...

Thomas Prufer

So possibly not too good for cast iron soil pipes?

reminds me of the theatrical landlady's sign: "If the chamber pot is used during the night, do not replace under the bed, lest the fumes rot the springs."

It will be diluted as soon as you flush it into them.

All plastics and ceramics in my WC, even the flushing lever is plastic.

Hence the full face respirator I wear when using it. Although, if I didn't have one, I would probably just pour it at arm's length and hold my breath. :-)

There was a TV programme where the criminal dissolved a body with concentrated hydrochloric acid. They were detected because of the cough they got from inhaling the fumes. It is not nice stuff, but is useful when used with care.