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Removing Mineral Stains

by stevorama » Apr 30th 16 5:24 am

Just got this pot. It appears unused except for mineral deposits around the outside rim of the pot, lid and spout. I've tried a few things, but haven't been able to remove the scale. Searching the forum I've found mention of citric acid, but I'm not really sure how to apply it here. Any suggestions for removing this?

It's a little hard to see in the picture, but it's a light ring around the rim of the pot, lid and a thicker ring on the end of the spout.
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Apr 30th 16 7:10 am
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Re: Removing Mineral Stains

by jayinhk » Apr 30th 16 7:10 am

Citric acid or maybe a baking soda scrub would do it...or maybe you could just live with it? I use a brush on my pots now, but my older pots have calcium deposits. I just treat them as patina. I built them up through use after all!

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Re: Removing Mineral Stains

by stevorama » Apr 30th 16 2:34 pm

jayinhk wrote:Citric acid or maybe a baking soda scrub would do it...or maybe you could just live with it? I use a brush on my pots now, but my older pots have calcium deposits. I just treat them as patina. I built them up through use after all!
I use a brush now too. This pot came like this. I guessing it's from pour tests in the past with really hard water? I tried baking soda scrub. And soaking combined with lots of rubbing with a cloth. Currently trying a several days soak in carbonated distilled water (to get lower ph.)

How would I use ctric acid? Could I just put a solution on those areas without a full soak of the teapot?

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Re: Removing Mineral Stains

by jayinhk » Apr 30th 16 2:55 pm

stevorama wrote:
jayinhk wrote:Citric acid or maybe a baking soda scrub would do it...or maybe you could just live with it? I use a brush on my pots now, but my older pots have calcium deposits. I just treat them as patina. I built them up through use after all!
I use a brush now too. This pot came like this. I guessing it's from pour tests in the past with really hard water? I tried baking soda scrub. And soaking combined with lots of rubbing with a cloth. Currently trying a several days soak in carbonated distilled water (to get lower ph.)

How would I use ctric acid? Could I just put a solution on those areas without a full soak of the teapot?
I would use it as a dilute scrub depending on concentration. I think you'd still need abrasion to get the lime deposits moving. Some pots are stained this way intentionally to look older, but maybe it was just tested or used with very hard water? Try lemon juice maybe (citric acid). I believe that's what people use to remove lime scale from kettles. We have incredibly soft water in HK, so scale is almost a non-issue here, but NY water was a lot harder!

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Re: Removing Mineral Stains

by stevorama » Apr 30th 16 7:07 pm

jayinhk wrote: I would use it as a dilute scrub depending on concentration. I think you'd still need abrasion to get the lime deposits moving. Some pots are stained this way intentionally to look older, but maybe it was just tested or used with very hard water? Try lemon juice maybe (citric acid). I believe that's what people use to remove lime scale from kettles. We have incredibly soft water in HK, so scale is almost a non-issue here, but NY water was a lot harder!
I'll look for citric acid this weekend and give it a try. This is one of EOT 90s teapots. It seems otherwise unused. That's why I thought it might be from pour testing, but perhaps something else.

My home water is good. Deep well water. It will leave slight deposits, but only if I don't wipe them off!

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Re: Removing Mineral Stains

by jayinhk » Apr 30th 16 8:07 pm

Groundwater is usually harder; our water here is from rivers and rainfall catchment.

A new pot with stains? That is interesting. I'd try the lemon juice thing first. You might not need the citric acid!

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Re: Removing Mineral Stains

by stevorama » Apr 30th 16 9:14 pm

jayinhk wrote:Groundwater is usually harder; our water here is from rivers and rainfall catchment.

A new pot with stains? That is interesting. I'd try the lemon juice thing first. You might not need the citric acid!
Yeah, I saw it in the pics before I purchased. Figured it would be easy to remove. I noticed a few of those pots looked similar (in the online pictures.) It's purely cosmetic, but I'm hoping to remove it before I begin seasoning the pot.

Wouldn't the lemon juice leave some lemony fresh aroma??

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Re: Removing Mineral Stains

by jayinhk » May 1st 16 3:54 am

stevorama wrote:
jayinhk wrote:Groundwater is usually harder; our water here is from rivers and rainfall catchment.

A new pot with stains? That is interesting. I'd try the lemon juice thing first. You might not need the citric acid!
Yeah, I saw it in the pics before I purchased. Figured it would be easy to remove. I noticed a few of those pots looked similar (in the online pictures.) It's purely cosmetic, but I'm hoping to remove it before I begin seasoning the pot.

Wouldn't the lemon juice leave some lemony fresh aroma??
Sure, but that should dissipate quickly. You could dissolve a vitamin C pill in water too I guess...ascorbic acid.

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Re: Removing Mineral Stains

by stevorama » May 6th 16 5:34 am

Soaked the pot for several days in citric acid solution. Took it out periodically to rub it with a coarse cloth and check progress. No change! Well, maybe a slight improvement, but not certain. Gave up today and finished with a baking soda scrub. Managed to remove the deposits on the tip of the spout with fine grit sandpaper tonight, but didn't want to risk that on the rim of the pot and lid.

Maybe this was something from firing and not mineral deposits.

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Re: Removing Mineral Stains

by jayinhk » May 6th 16 6:15 am

stevorama wrote:Soaked the pot for several days in citric acid solution. Took it out periodically to rub it with a coarse cloth and check progress. No change! Well, maybe a slight improvement, but not certain. Gave up today and finished with a baking soda scrub. Managed to remove the deposits on the tip of the spout with fine grit sandpaper tonight, but didn't want to risk that on the rim of the pot and lid.

Maybe this was something from firing and not mineral deposits.
I would've just lived with it. Perhaps the sand got fused to the clay...

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Re: Removing Mineral Stains

by stevorama » May 6th 16 2:34 pm

jayinhk wrote:I would've just lived with it. Perhaps the sand got fused to the clay...
Yes, just living with it is the next step. :wink: And it is a nice pot to live with. Given the price I was surprised there was this issue, but then I suppose the value is primarily in the clay, vintage and overall quality.

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Re: Removing Mineral Stains

by jayinhk » May 6th 16 3:22 pm

stevorama wrote:
jayinhk wrote:I would've just lived with it. Perhaps the sand got fused to the clay...
Yes, just living with it is the next step. :wink: And it is a nice pot to live with. Given the price I was surprised there was this issue, but then I suppose the value is primarily in the clay, vintage and overall quality.
I guess you could've returned it before all of the attempts at removing the stain/residue/whatever it is. EoT might still take it back...who knows? I'm using an 80s F1 pot right now that has chips and lots of internal staining, and it still has an aroma of something tea/herbal that I can't get rid of, but boy, does it ever make good shu!

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Re: Removing Mineral Stains

by stevorama » May 6th 16 5:51 pm

jayinhk wrote: I guess you could've returned it before all of the attempts at removing the stain/residue/whatever it is. EoT might still take it back...who knows? I'm using an 80s F1 pot right now that has chips and lots of internal staining, and it still has an aroma of something tea/herbal that I can't get rid of, but boy, does it ever make good shu!
I don't want to return it. Like I mentioned it's a good pot! I'm just learning more about yixing and what determines value and also what I value. Now, onwards to pairing and enjoyment of the teapot!

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Re: Removing Mineral Stains

by pedant » May 6th 16 5:53 pm

just fyi to anyone reading this in the future, another thing to try is vinegar -- distilled white vinegar from any grocery store.
works the same as citric acid (except temporarily smelly until you rinse it out), and it might be easier to find.

yeah if an acid soak didn't get rid of it, it isn't mineral stains from water.
that stuff will easily dissolve in acid without any scrubbing -- pretty quickly in warm or hot solution, but perhaps overnight at room temp.

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Re: Removing Mineral Stains

by stevorama » May 6th 16 6:21 pm

pedant wrote:just fyi to anyone reading this in the future, another thing to try is vinegar -- distilled white vinegar from any grocery store.
works the same as citric acid (except temporarily smelly until you rinse it out), and it might be easier to find.

yeah if an acid soak didn't get rid of it, it isn't mineral stains from water.
that stuff will easily dissolve in acid without any scrubbing -- pretty quickly in warm or hot solution, but perhaps overnight at room temp.
I considered the vinegar. The citric acid was available in bulk at the local health food store. Easy to find online too.