# Cause of blue stain bowl (not just a ring)



## gmaint (Feb 21, 2014)

_Pumice stick are just stone sponges, Used them for the last 26 yrs in apartments with no surface damage.

_


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## tearitup (Jan 4, 2015)

Whether pumice puts visible / almost invisible scratches in porcelain - can't say.
Tons of people say they used pumice sticks & it did dulled the super shiny porcelain - a little or lot. Others say it doesn't.

Either way, it's an abrasive. This blue stain or similar stains often appear to be "soaked in" the porcelain. If so, seems pure abrasives that don't have any additional "soaking" cleaners, can only remove such stains by removing part of the porcelain.


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## Homerepairguy (Aug 1, 2010)

tearitup said:


> We have 2 toilets, his & hers, almost back to back on opposite sides of a wall.
> One gets blue stain in the bowl, the other doesn't.


Are both toilets the same brand and model? Assuming both have been maintained in the same way, I'm wondering if it's the toilet itself that's the source of the problem.


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## PoleCat (Sep 2, 2009)

Our toilet developed a weird blue stain in the channel where scrubbing is less effective. I used muratic acid on it. Right out of the bottle. It took care of the stain. This can be a very risky operation. Hazardous fumes are created and need to be vented outside. The water needs to be removed so it dose not immediately dilute the acid. If you are clumsy you will get burnt.


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## tearitup (Jan 4, 2015)

Thanks.
FYI, here's a similar pic of what we see (the color, anyway).
Unlike the pic, ours isn't the entire bowl (under water line), nor quite as dark - but is same shade blue.

I tried (diluted) muriatic acid on the dry porcelain. But not straight acid & it runs off fairly fast. Possibly, anything that *may* remove this, has to stay in contact for hours / overnight. Likely means pouring it in the full bowl. 
On a small spot, could rub straight muratic - just to see. Leave on V. short time & rinse. 
***ANYONE reading this*, muratic acid is commonly available - hardware, pool supplies; but it WILL burn you / eyes. For strong cleaners (especially "off label" uses), always use protective equipment, good ventilation, etc. NEVER mix products, unless positive that it's safe.

Didn't try straight muriatic, mainly as some sources say even porcelain can be etched by * some * really strong products. It's tough, but not indestructible. I don't know how strong a specific acid has to be, how long it's left on, etc., to etch porcelain.

I could pour one of various acid "bowl cleaners" in the water, overnight. But not till it warms up & window can be cracked. Same w/ chlorine bleach (NOT at same time ).

Problem - I've read many "causes" of this blue stain.
What will clean any stain depends on what caused it. 
A common reason claimed for blue stain is slow corrosion of copper pipes - often said from acidic water supply (we have alkaline).

Only one toilet gets it, AFAIK. There's a reason why - may never find it.

- Homerepairguy - not the same brand johns, but guts are the same, AFAIK. Same fill valves, same type plastic flush valves / rubber flappers. I'd have to check if "tank-to-bowl" bolts are same. Same copper water lines, chrome shut off valves, flexible hose from stop valve to fill valve (rubber w/ steel braid), etc. 
Comment if you have other things to check.

- PoleCat - "channel" - you mean at very bottom on bowl, where bowl narrows to a few inches wide? This stain isn't that deep, but few yrs ago, I had this john outside during remodel. Very bottom had other stains - I poured straight muratic in w/ some water in very bottom. 

Cleaned it, but wasn't covering entire bowl (& was outside).
Yes, could open the window, cover door opening w/ plastic. Hopefully even small fan in window.


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## PoleCat (Sep 2, 2009)

I have treated many toilets with muratic acid to get rid of scale deposits. In our particular case at home I believe (and this is just a hunch) that blue dye in the toilet bowl cleaner we used stained a film of calcium deposit in the trap area. I wet it with acid and left for 30~60 minutes.

I worked at a place that had very very hard water. The scale build up would restrict the channels to the point the toilet wouldn't flush anymore. Muratic acid to the rescue.


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## tearitup (Jan 4, 2015)

SOLUTION:
Unfortunately, this forum doesn't seem to allow adding "Solved" or such to topic subjects.

What finally got the blue stain out was bleach (sodium hypochlorite).*
Straight muratic acid (hydrochloric acid ~ 34%) didn't touch it.
Not everything is soluble by acid.

I removed / pushed at least 1/2 the water out of bowl (maybe 3/4?).
Then slowly poured in clorox until the stains were covered.
Kept door shut & window open.

Took hours of soaking, but it removed all the stain.
Can't say for sure if it actually removed the "deposits" (probably some copper compound), or just bleached the color out.

* NOTE: many consumer grades of bleach used to list the concentration (% hypochlorite) on labels. I don't see that any more. Used to, cheap brands of bleach were much less concentrated. I imagine that's still true.

I used a name brand, slightly more expensive bleach.
For other uses where I've needed to "bleach the color out" of something, including removing algae, etc., bargain brand bleach sometimes didn't work nearly as well. Even full strength. Keep that in mind if trying to remove stubborn toilet stains.


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## David Stachan (Oct 19, 2021)

tearitup said:


> We have 2 toilets, his & hers, almost back to back on opposite sides of a wall.
> One gets blue stain in the bowl, the other doesn't.
> The one w/ stain is hers.
> It's definitely stained into the porcelain, not a layer on top.
> ...


We struggled with exactly this problem for months. Finally solved the problem overnight! We now believe that the porcelain was stained by a blue cleaning fluid. The above article and its comments led to our solution. We drained the bowl and placed flannels soaked in Clorox around the stained area. The next morning 90% of the stains were completely gone and the rest went after we repositioned the flannels. We no longer use blue cleaning fluids. 
In the above case, we are left wondering if a blue cleaner was used in just one of the two toilets?


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