I often see announcements of copper pots that condition:
"no lack of tin", "tin in place", "tin natural oxidation, no worries to cook", etc ...
Indeed, over time, tin becomes dull gray, stained, it is a natural action on tinning that does not pose a problem for cooking. If you buy a copper pot of this type, simply clean it well.
But ... traces of limestone, fat, calcination, oxidation, often in the form of crusts (very fine), can hide the real state of tinning.
To detect this one must have a professional eye.
In photo 1, you see a pot bought in a flea market. We see that there is no lack of tin and it seems in a good state to cook.
But this does not tell us if the tinning is correct below the spots and "crusts".
In photo 2, I apply a hand cleaning that is equivalent to some acid cooking such as tomato sauce.
In photo 3, after the rinsing, we can already see on the right that the bare copper begins to appear. There are black "crusts" all around at the top and next to the rivets.
In photo 4, I redid a cleaning, we see the black "crusts" that disappear and do not show more bare copper.
In photo 5, finalization with a final cleaning. The black crusts are almost totally gone.
From the first cleaning (photo 3) it is clear that the tin layer is weak on the right. With the last cleaning (photo 5), all the "crusts" black almost disappeared. This last cleaning does not show much more bare copper than the first cleaning.
Visually we know that the time has come to make a new tinning.
When we buy a pot like this, we can not know how long tinning could be faithful.
It is not clear exactly how long it has been used.
We do not know the thickness of the tin layer.
It is not known if this pot was stored in the humidity.
What many people do not know:
We do not know if this pot was stored in the cold. For example in a cellar, an attic, a garage, a barn, outside on the edge of a window with a plant in it!
For how long ? 1 year, 2 years, 10 years, 20 years, 50 years ?????
The action of the cold on the tin can be devastating without being noticed visually. Below -13°C the mechanical behavior of tin begins to change.
In the north of France it will be easy to have winter periods down to -10°C, -15°C, -20°C.
In the south of France it will be more rare!
Below -50°C tin can turn into powder! But we do not meet this type of temperature at home!
In the case of this pot, I can tell you that tinning will not last long! The action of the acid cooking, the friction of the utensils will quickly eliminate the too thin layer of tin which remains on the right.
Nothing is win in advance by buying a used copper pot. We can do a very good purchase and cook only a few times before we see the bare copper. This is the case of this pot.
But we can also do a great deal and cook for years! Everyone's lucky!
My advice will be to choose a used copper pot that does not show "crusts". That these "crusts" are black (Do not confuse with black dots in "hollow" that can be found on new tinning. Some copper pots that have worked a lot have been hit by utensils, knives, etc ... So hollows and it is very difficult sometimes for the tinsmith to remove them. Very very difficult. This is why sometimes in new tinning we can still see some black point without gravity for cooking.), white, brown, gray, we do not know what is hidden below!
And even worse, green "crusts" !!!!!!!
In a used copper pot, prefer smooth tinning. Even if it has spots, if it is dark.
Absolutely avoid a pot with "crusts". Tinning is a wonderful material for cooking. It rarely sticks to food and is very easy to clean. So when there are "crusts" it is either because it was stuck on the bare copper, or because the former owner was not very careful in his cleanings!
To all Copper Lovers ! Regards, T.J.
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