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Homemade Rokusho : another method


Hi there :slight_smile:
It’s been a long while I haven’t been posting here, but today I just came up discovering something that might be interesting.
(English is not my native language so I apologize for any mistake i could do)

Some time ago i tried making my own rokusho with the methods described here :

That was nice but not really “easy” : since i had no way of finding the reagents arround, i had to dissolve copper in acetic acid, then in nitric acid, and then in hydrochloric acid, and let evaporate each of the solutions. Despite the use of a catalyst (hydrogen peroxide) it took weeks to get my rokusho.

So today I’m sharing another way of doing it faster, i hope you find it interesting :slight_smile:

First of all, we need two reagents : In France i can find them quite easily in hardware or gardening shops.
Those are cupric sulfate and sodium carbonate (not bicarbonate)

First, we mix both powders, about 50/50, in a plastic or glass container. Then, by adding some water, the reagents react to form copper carbonate, sodium sulfate and carbon dioxide. It might contain some traces of the former reagents too.
( 2 CuSO4 + 2 Na2CO3 + H2O → Cu2(OH)2CO3 + 2 Na2SO4 + CO2 )
It takes one or two hours to react, the best is to just let it sit overnight before going to the next step

Since copper carbonate is the only reagent here to be water-insoluble, we simply add more water, stir well and let the powder fall at the bottom of the container to decant it.

We repeat the process until water is quite clear (on the photo is shown the first decantation, it has to be clearer than this, about 4 or 5 times is okay), and then filter or let evaporate to get copper carbonate in powder.

The powder finely ground :

Then, we can use that copper carbonate to make the other reagents very easily :
Copper chloride > mix copper carbonate
with hydrochloric acid.
Copper acetate > mix copper carbonate
with acetic acid (or white vinegar)
Copper nitrate > mix copper carbonate
with nitric acid.
It’s better to saturate the acid with copper carbonate, by doing so we make sure there’s no acid left at the end of the reaction.
Then we let evaporate each, mix each powder together with the remaining copper carbonate, finely ground it and that’s all. The resulting powder is blue or green, depending on the proportions, copper chloride and acetate turn it greener. (Which, in my opinion, is better to achieve good patinas)

I hope you found it useful :slight_smile: Have a nice day !