Jan 8th 16 11:59 am
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Re: What kinds of kettles were used historically?

by .m. » Jan 8th 16 11:59 am

William wrote:Silver kettles aren't made out of pure silver... the silver is mixed with other metals...
One can say this about most metals. When talking about tea, tin/pewter comes certainly to mind for its historic use, but nowadays the most important would be stainless steel, which can sometimes impair a slight metallic taste, depending probably on the composition.
My dog would not like to drink his water from one stainless steel bucket yet he would happily drink from another one. While i don't really know why (aside from that he was a notoriously difficult creature (but then who isn't)), it could be that he didn't like the taste.

Personally, I'd be perfectly happy with a sterling silver kettle ;)

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Jan 8th 16 12:18 pm
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Re: What kinds of kettles were used historically?

by Drax » Jan 8th 16 12:18 pm

William wrote:
pedant wrote:e come mai?
:lol: :lol:

Silver kettles aren't made out of pure silver, because it would melt. In order to avoid this, the silver is mixed with other metals, that usually spoil the flavours of tea. Even if just for luck, the effect was good, a couple of people involved in metal industries warned me of possible health issues related to silver nanoparticles, so no reason to take any risks, at least for me, considering the myriad of alternatives.
Wow. I'm not even sure where to begin. Ok, let's start with the obvious misinformation about melting points.

Metal, MP in C, MP in F (from this site)
Aluminum 659 1218
Silver (pure) 961 1762
Silver (sterling) 893 1640
Stainless Steel 1363 2550

Silver isn't going to "melt" when heating it on a stove. Further, mixing silver with other metals (such as copper, to make sterling silver) actually lowers the melting point, so again, your statements were incorrect.

And finally, "silver nanoparticles" are very different from a fabricated piece of silver. I would need to see some sort of science article (and not heresay) if you're going to claim otherwise.

Jan 8th 16 3:34 pm
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What kinds of kettles were used historically?

by PAQF » Jan 8th 16 3:34 pm

+1

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Re: What kinds of kettles were used historically?

by William » Jan 8th 16 3:45 pm

Drax wrote: Wow. I'm not even sure where to begin. Ok, let's start with the obvious misinformation about melting points.

Metal, MP in C, MP in F (from this site)
Aluminum 659 1218
Silver (pure) 961 1762
Silver (sterling) 893 1640
Stainless Steel 1363 2550

Silver isn't going to "melt" when heating it on a stove. Further, mixing silver with other metals (such as copper, to make sterling silver) actually lowers the melting point, so again, your statements were incorrect.

And finally, "silver nanoparticles" are very different from a fabricated piece of silver. I would need to see some sort of science article (and not heresay) if you're going to claim otherwise.
1. To some teachatters (even myself) happened to have silver kettle that deformed (the lower part) because of the lower melting point, especially those made in Japan whose purity is usually around 95% or so. Of course it couldn't totally melt in any way, nobody uses a source of heat equal to or exceeding of 900 degrees centigrade; this doesn't mean that silver kettles will not deform on the lower part over the course of months/years, especially on stove/hot plates.

2. Silver mixed with copper or aluminum actually spoil the flavours of tea, if you can't detect it doesn't mean it's not true.

3. I am not in metal industries nor a scientist, but due to the qualified sources, I thought fair enough to share it with other teachatters, even just to make recognizable this aspect.
PAQF wrote:+1
Thanks for your interesting and important contribution to this discussion, my friend.

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Re: What kinds of kettles were used historically?

by wyardley » Jan 8th 16 7:03 pm

I have personally seen a melted silver kettle (melted on a regular stove, if memory serves), and I know that this problem is part of why you don't see silver kettles used with charcoal stoves.

Of course, I think there are two different questions here; one is "what type(s) of kettles were considered ideal historically", and the other is "what were used historically".

I have seen copper or bronze (not sure exact composition) Chaozhou style kettles, designed for use with small charcoal stove, but I'm not sure how far back these were used.

Jan 25th 16 1:39 am
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Re: What kinds of kettles were used historically?

by PAQF » Jan 25th 16 1:39 am

William wrote:
PAQF wrote:+1
Thanks for your interesting and important contribution to this discussion, my friend.
Actually, it was not a brilliant contribution. My apologies. :oops:

I was a bit sceptical about the whole issue so I asked a collegue from my Department that works in Gold Chemistry and, to my amazement, he pointed me towards a paper (in a reputed scientific journal).The article details are:

Generation of Metal Nanoparticles from Silver and Copper Objects: Nanoparticle Dynamics on Surfaces and Potential Sources of Nanoparticles in the Environment
Richard D. Glover, John M. Miller, and James E. Hutchison
ACS Nano 2011 5 (11), 8950-8957
DOI: 10.1021/nn2031319


In lieu of the contents here is a short summary:
  • The authors observed the spontaneous formation of silver nanoparticles from every day objects (an earing, an spoon and a fork) in humid environments and water. Similar observations were obtained when using a wire of copper.
  • The process was observed at room temperature.
  • The mechanism of the formation of the nanoparticles seems to be related to the metal redox properties. The mechanism is complex but it involves (i) the oxidation of the metal (Ag --> Ag[sup]+[/sup], Ag[sup]+[/sup] is soluble), (ii) diffusion, and (iii)reduction of the metal and formation/growth of the nanoparticles.
The paper did not examined if these nanoparticles constitute a health issue.
Last edited by PAQF on Jan 25th 16 2:18 am, edited 2 times in total.

Jan 25th 16 2:11 am
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Re: What kinds of kettles were used historically?

by PAQF » Jan 25th 16 2:11 am

Continuing with my previous message.

I will be weary of labelling silver kettles, silver tableware or copper tea caddies as a potential health risk. After all, we have been in contact with naturally occuring nanomaterials for millennia, though we were not concious of it till a few decades ago.

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Jan 25th 16 8:12 am
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Re: What kinds of kettles were used historically?

by William » Jan 25th 16 8:12 am

Thanks for your contribution, but so far the thread looks dead! :D