Avoiding and dealing with limestone buildup inside kyusu

[Cifer]

Hello everyone,

First, some background info:

I live in an area with fairly hard water (about 250 ppm). I use spring waters with a hardness of 63 ppm or less to brew teas in my unglazed kyusus, but hot tap water with a hardness of about 250 ppm to rinse out the leaves and clean the pot, followed by a quick rinse with filtered hot water with a hardness of 140 ppm.

And here my questions:

1. Since 140 ppm is still fairly hard water, I'm wondering whether it would be better to use cold water to clean the kyusu because, as I understand, water leaves behind more lime when it evaporates. The reason why is use hot water is because the kyusu dries much quicker after, but I'm not sure if there would be a noticeable difference between long-term limes ale buildup depending on the temperature and evaporation. Does anyone have experience with this, or any insights?

2. As all water contains some minerals, I presume that no matter what, sooner or later lime will build up in the kyusu from the 60 ppm water I use to brew in it alone. If I'm right, what is the best way to remove lime without making the pot unusable? I've heard vinegar is the most foolproof method as it evaporates and leaves behind no unwanted scents or tastes. At the same time, I've heard some people say that it left behind an odour, and I can't tell if that's nonsense (read: scientifically impossible), or not.
Is it the best option? Is citric acid an option at all or a bad idea?

Thanks a lot!

[Bok]

I use citric acid to good effect.

[wave_code]

second what @Bok said. I have really hard water here so I try and keep it out of my pots, but sometimes using the 'good' water to clean something out gets excessive, or the water is out. I usually do hot rinse, try to get as much of it out of the pot as possible or dry it out with a towel, and sometimes also give a final little 'rinse' with my good water. But I still every once in a while will give a pot I use a lot a citric acid soak just to re-set things if I feel like the clay isn't performing right.

[Cifer]

Thanks a lot, I'll try citric acid if I ever need to descale a ceramic pot.

Do any of you have experience with citric acid vs. vinegar? Is one better/safer than the other for ceramic pots?

[polezaivsani]

@Cifer, you most certainly want to use citric acid . I used a rather thick solution of vinegar on one occasion. It had little to no evident effect beyond what citric acid would have, and then I've been airing out the smell for something like a month. A lighter solution would vaporise completely faster, but I haven't seen it do anything citric acid won't be up for. Also all this is thoroughly covered in the cleaning topic here if you fancy.

[pedant]

no need to get citric acid if you already have white vinegar (distilled vinegar). rinse thoroughly, and the smell will go away quickly.

running boiling water through it should help it air out even faster.

[pedant]

I've been airing out the smell for something like a month.

interesting, what kind of teaware? haven't had this issue

[polezaivsani]

@pedant, that was me cleaning a lovely f1 hongni pot. Soaked it 70% acetic acid for half a week for no apparent effect other than the stinging smell.

[pedant]

pedant, that was me cleaning a lovely f1 hongni pot. Soaked it 70% acetic acid for half a week for no apparent effect other than the stinging smell.

huh, i wonder why. it's always removed scale fine for me. even in tea kettles. i used to use it all the time before i bought an espresso machine (and then i got a lifetime's supply of citric acid).

also, wow... 70% acetic acid is really strong! where'd you even find that?

[polezaivsani]

huh, i wonder why. it's always removed scale fine for me. even in tea kettles. i used to use it all the time before i bought an espresso machine (and then i got a lifetime's supply of citric acid).

Sorry for a clumsy explanation—it had no effect beyond what citric acid would have. I used citric acid first, and then, being irked by one pesky spot or a tad overly pedantic (pardon my french), tried acetic as a means of last resort. And then some physical pecking with a (not really) electron microscope in hand. Did a good number ritual offerings to gods of rock (or, not to offend the religious folks here, where they stoned gods?) afterwards to put the perplexed shuiping back into good shape.

also, wow... 70% acetic acid is really strong! where'd you even find that?

$1 piece in a spices section at a local grocery . Here where a bunch more jokes about tsars and hazardous chemicals that could land one in prison, should the locally grown apparatus ever run out of heretic passages in native language.

[.m.]

I can't imagine how simple rinsing with hard water could create limescale buildup. Is that an actual issue, or just a precaution?

[teatray]

As all water contains some minerals, I presume that no matter what, sooner or later lime will build up in the kyusu from the 60 ppm water I use to brew in it alone. If I'm right, what is the best way to remove lime without making the pot unusable? I've heard vinegar is the most foolproof method as it evaporates and leaves behind no unwanted scents or tastes. At the same time, I've heard some people say that it left behind an odour, and I can't tell if that's nonsense (read: scientifically impossible), or not.
Is it the best option? Is citric acid an option at all or a bad idea?

I think your presumption is not necessarily correct. The 63ppm (presumably ph ~7) water could very well leave no limescale at all, that is calcium, etc. could prefer the solution & not form deposits, esp. since you're not heating it in the pot. (It could even be that it doesn't form any in the kettle.) The higher-TDS water (which would probably deposit a good amount in a kettle), when used for rinsing only, may not be much of an issue--it's not for me. Though I do often boil & fill the teapot with good water after rinsing (for hygiene/quick drying, removing tap water taste, etc.), esp. with teaware I care about.

[Baisao]

Not all minerals lead to lime scale. It’s primarily calcium carbonate. This is why water softeners can exchange the calcium for sodium yet not have scale accumulate.

I use 20% acetic acid in my photo chemistry and it is hot stuff. I can smell it though the chemical resistant lid of the glass bottle. It stinks up my chemical storage space. Glacial acetic acid is nasty smelling stuff so I’m not surprised the odor lingers.

I used to clean dozens of Tokoname bonsai pots each year for shows, both glazed and unglazed. All of them would develop severe lime scale deposits.

Cleaning dozens of planters each year is a strong motivator to find an effective and safe solution. Here’s what didn’t work: acetic acid (no effect), citric acid (no effect), CLR (limited effect and hazardous), baking soda scrub (no effect), 3M foam sanding pads (damaging).

The best solution I found was to use a paste of walnut powder and water, scrubbed with a Magic Eraser. It takes effort but not much. The abrasive is harder than lime scale but softer than the clay and glazes.

[wave_code]

pedant, that was me cleaning a lovely f1 hongni pot. Soaked it 70% acetic acid for half a week for no apparent effect other than the stinging smell.

huh, i wonder why. it's always removed scale fine for me. even in tea kettles. i used to use it all the time before i bought an espresso machine (and then i got a lifetime's supply of citric acid).

also, wow... 70% acetic acid is really strong! where'd you even find that?

Also tried vinegar on two different pots- never again. Both were very absorbent clay and it took a very long time to get rid of the effect of the vinegar.
For citric acid personally I just use the powder form you can buy at the grocery store here for descaling your kettle, eyeball measurement.

[debunix]

I will now have to find a different purpose for some distilled white vinegar that I bought for cleaning teawares, after a wonderful experience using citric acid to de-scale in electric kettle, that had stopped properly sensing temperature because of the thickness of the scale on the bottom of it. It is now shiny and clean on the inside, temperature control and function are now back up to snuff. And there was no blast of undiluted vinegar stink involved, or any trace of citric acid taste in the tea I prepared today.