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Blacking of brass:

The metal that most modelers make from all metal fasteners, mechanisms and finishes is brass. Because it is easy to process and we have a wide choice in the market for this metal in the form of wire, tubes, plates and wires. There is also a need to make this shiny black gold metal. But have a natural black metallic metal color. This can only be achieved by chemical means. You can buy a ready-made jar of magic liquid or you can make the solution yourself. Of course different methods - give different results of black effect. I will also share my experience of blacking out "at home" and with the help of an unknown liquid from the store shelf ...

Blackening at home.

To prepare the liquid you will need:
1. A solution of ammonia 20-25%;

2. Copper sulfate CuCO4;

3. Sodium carbonate (baking soda) NaHCO3;

4. 2 glass jars;

5. Dense filter cloth

1. CuCO3 copper carbonate
You can use sulfate, acetate or copper nitrate to obtain it. A solution of potassium or sodium carbonate (soda) is poured into an aqueous solution of one of these salts. The result is a green-blue precipitate consisting of a basic carbonate of variable composition, which is not very important to us in this case. The precipitate is filtered and can be used.

So, to prepare CuCO3 copper carbonate, we will need CuCO4 copper sulfate, which is usually sold in every flower shop as fertilizer or pest control chemicals. And the NaHCO3 baking soda from a nearby grocery store. Glass jar and stick for stirring ...

2. The process of obtaining copper carbonate CuCO3
So first we pour into the first jar half warm water and begin to dissolve the copper sulfate stirring constantly. When crystals cease to dissolve, this means the maximum concentration of it in water. The solution will be transparent and bright blue.

Now we start to pour a little soda, the process will be turbulent and that is why we filled the tank by half. And then just as long as there is a violent reaction. The result is a very liquid turquoise texture. That is why we need to strain it. I used a dried wet cloth. So got CuCO3 copper carbonate, as pictured ...

3. Brass blacking solution
Obtained turquoise lime, it is desirable to dry for the purity of the experiment, but in the wet state everything works. For the work does not hurt the mask, as we will start to use ammonia (which contains a solution of ammonia, in pharmacies in the free sale can buy 10%).

Therefore, pour into the jar ammonia and gradually dissolve the resulting carbonate of copper to a deep blue transparent color. The solution is ready.

The casting process takes 10-30 minutes. That is, you throw details there and go drink coffee.

Not convenient: you have to wait and the solution has a sharp smell.

Blackening chemistry from the store.

Today, on the shelves of stores you can find any chemistry and with different shades of blackening of metal. The only issue is the cost. But the benefits of specialized chemistry are that you instantly get results. You do not have to wait half an hour for the metal to react. And if we use soldering on brass, then we also need to blacken the tin, which is a completely different metal and copper sulfate will not help here. So I prefer chemistry from the store.
Advantages: instant results and more choice of possible cuts and effects of aging.