Mar 18th 20 9:19 am
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Iron vs Silver II (Brewing comparison)

by umijoshi » Mar 18th 20 9:19 am

Following up on my previous post I would like to share information about brewing different teas with water boiled in an iron kettle vs a silver kettle. The test was conducted on Thursday March 12th 2020 from approximately 8:30am until noon. I would like to state that I tried to be unbiased here in the sense that I didn’t have a favorite to win.

I started by re-doing a comparison of the straight boiled waters again to set my bearings:

Silver Water:
No aroma. There is a white softness to the otherwise perfectly transparent water, perhaps it is due to calcium build up on the silver. In the flavor I feel that it has a film to it, again perhaps due to calcium build up. The water feels soft and easy to drink.

Iron Water:
Aroma has a salty minerality. The flavor is noticeably different – it has a very strong rocky, dusty, brown sandy quality to it. The aroma reminds me of a humidifiers air which I suppose makes sense due to humidifiers generally having a heavy calcium buildup over time.

In direct comparison — anyone could tell the difference I would think.
My 3 biggest take-aways from comparing the water would be:

1) Texturally the silver water feels very smooth and ’rounded’ due to the filmy coating it leaves behind. Iron water feels sharper or edgier.
2) Flavor difference is unmistakable. The distinct sandy notes that the iron water gives is akin to the sand used to cast molten metal in a sand mold (the kind of thing you do in shop class when you’re 11 years old~) The flavor of the water is like the aroma of that sand.
3) The iron rich water has a finish to it, it lingers and leaves an irritating dry feeling in the throat. The silver water is pure, I don’t feel there is any finish at all.

If I was just drinking water, I would prefer to drink silver. Anyone could taste the difference between the two if they were lined up like this, and I am confident I could pass a blind taste test of the waters 100% of the time.


In tea, I have compared a Sichuan Chinese green tea called Meng Ding Gan Lu, Taiwanese Red Oolong Tea called Mi Xiang, and a Ceylon silver tipped black tea. All teas were tested with the following parameters: Ratio of 4.4g:330ml (1:75), 2 minute steeping time, rolling boiling water.

Meng Ding Gan Lu Green Tea:
The color of the silver tea is yellower. The iron tea is greener. The clarity of both teas is pretty much the same. The aroma of the iron tea is smoother, softer. Both teas have a cooked yellow lentil quality to them but the iron water smells more ‘cooked’ and deeper. The silver tea seems to have more aromas, especially hitting ‘high notes’. The iron teas aroma is more homogenized and pleasant. The silver tea has more clarity in the flavor and seems more ‘lively’ overall but finishes with more noticeable astringency. In comparison the iron water seems somewhat dull but fuller in flavor and the finish seems longer and more pleasant.

Conclusion: In Meng Ding Gan Lu silver rich water has more upfront flavor but iron has more backline finishing power and texture. I give the victory to iron.

Mi Xiang Red Oolong Tea:
The color of the silver tea is definitely darker and much browner compared to paler orange iron tea. Iron has much better clarity due to the lack of color. The aromas are quite different. Silver was much more molasses-y and in the direction of pumpkin pie, I described the aroma as tangy, brown, sweet, spicy vs the iron teas aromas of ‘beauty oolong’ akin to high quality Oriental Beauty and extremely fruity in the direction of pink grapefruit juice. Based on the large difference in color and aroma, I would think I was drinking two completely different teas. The flavor of the iron water is smooth, gentle, fruitier and more honey-like. The flavor of the silver is more intense, drier, astringent, deeper in the caramelized flavor zone with strong molasses notes.

Conclusion: Wow. I am not sure which is better but they are quite different, this was very surprising. I guess iron? That level of sophistication to compare this to a high level oriental beauty is high praise.

Silver Needle Ceylon Black Tea:
The color is about the same, the silver is a bit darker, a bit redder. The aroma of the silver tea is more appealing, is has more character and distinctive notes especially ones comparable to mulchy autumn leaves. The difference in aroma is subtle though, especially compared to the previous two. Flavor wise the silver tea is clear and simple, astringency stands out. The iron water has more sour flavors but a much more impressive finish. The major difference between both metals in this black tea was in the finish. I would say Iron wins.

Reflecting on the test over all, I would say it was a success. I have formed some opinions based on this which I will carry towards the future to help me deliver the specific flavors I want my customers to experience.


The TL;DR take aways:
– The sandy aroma and flavor of iron rich water is not detectable (at least not by me) in tea
– Silver will consistently brew a darker colored tea than iron 3/3
– Aromatically 2/3 teas were better with iron water
– Silver has more clarity of flavor and is consistently more intense than iron 3/3
– Finish quality and length are consistently better with iron 3/3
– Astringency was consistently more obvious with silver water 3/3
– 1/3 teas showed a massive difference in flavor and aroma, 2/3 was somewhat negligible, so depending on the tea being used there is a varying effect of the water
– Iron was my preference 3/3
– I believe it would be worthwhile for a serious tea institution or brewer to experience their selection of teas with both waters to decide which to present to their customers and to choose them case by case.
– Since astringency is a controllable factor heavily influenced by temperature I would say that brewing tea with iron water is ‘easier’ and that by changing parameters such as temperature might make silver the winner. However in this test, all parameters being equal, I think silver lost.

Apr 6th 20 2:17 am
Posts: 49
Joined: Jan 7th 14 7:41 am
Location: Calgary, Canada
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Re: Iron vs Silver II (Brewing comparison)

by umijoshi » Apr 6th 20 2:17 am

A new study I have read lines up with my recent conclusions, I felt its quite interesting as well:

The study:
The Influence of Water Composition on Flavor and
Nutrient Extraction in Green and Black Tea by
Melanie Franks, Peter Lawrence, Alireza Abbaspourrad and Robin Dando ... -00080.pdf

From 4. Conclusions:
"The high mineral content of the tap water used in this study led to
inferior extraction of catechins in green tea, and thus, produced an infusion that was less bitter, and also
perceived as sweeter than the same tea brewed in bottled or deionized water, with an accompanying
higher degree of liking for green tea when brewed in this manner. For tea drinkers consuming green
tea for either flavor or its health benefits, our results highlight that the type of water used to brew tea
is clearly important, and suggests that those seeking greater health benefits should use a more purified
water source to brew green tea, while those more concerned with flavor may prefer to use water from
the tap."

The iron tetsubin coated in calcium precipitate would cause more calicum to be dissolved into the water used for tea, inhibiting extraction of catechins giving a better flavor

The silver kettle not giving the water additional minerality would extract more catechins and thus produce a tea with more bitterness/astringency/EGCG and health benefits

Which could perhaps being easily formed into a sentence...
"If you want health benefits from tea use silver, if you want a better flavor use Iron"