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ELECTROTYPING

 

Another very common electrochemical process of electrotyping, i.e., the deposition of a thick, solid layer of metal on the surface of any object, the form you want to reproduce, copy. The electroplating is used in cases where the metal parts are very complex form and in the usual way (by casting or machining) it is difficult or impossible to manufacture. So sometimes reproduce sculpture model (the chariot of Apollo on the pediment of the Bolshoi theatre made by electroplating); also encode with record-standard metal forms in which it is pressed records, exactly reproducing the finest relief grooves.

If you have no solution for copper plating, then cook it again. Take a piece of wax or paraffin, very carefully flatten its surface, so that it becomes possible flat. This smooth stretch scratch with a inscription, figure or pattern. I advise you to write your initials - then you'll have the monogram. It's best to write with a needle, just please don't leave too deep scratches.

With a soft brush, coat the surface with a pattern of electroconductive powder. You can, for example, crushed in a mortar of a slate pencil or graphite rod batteries. The edges of the picture press to the surface of the graphite-coated, thin bare copper wire (they will serve as the electrodes and connect them together. Wax cast hang in a glass, pour the electrolyte, lower copper electrode and collect the same pattern as in the experiments with applying chrome coating. But unlike galvanothermy it requires much less current, about 5-10 mA. So you have to move the slider of rheostat or find another radioprotective.

Turn on the current and be patient, because this current copper will be deposited on the graphite surface at least five hours, if not more, however, to increase the current is not necessary: the quality of the work will be much worse. Break the chain and remove wax from a glass mold. Carefully lower the wax in hot water-it will melt. And you will get a thin copper sheet with a pattern. Gently tear off his wire-grids. An exact copy of the picture is obtained.

You can now go to a very useful fact: manufacturing method of electrotype unique icons. They will only be in your collection! If in the circle you will make twenty or thirty Souvenirs, they will long remind you and your friends about Hiking, sporting events...

Tips artistic properties will not give: sketch create yourself. No need complex icons: and harder to do, and they look worse. The sketch cut a template out of thin cardboard - it should follow the outer contour of the icon. Place the template on a thin copper or brass foil and carefully cut it so many blanks, how many icons you're going to do.

Your workpiece is soft. It was hard, cover it with a layer of copper in the galvanic bath. In principle, you already know how to do it; here you will find advice in relation to making icons.

Billet poke at the edge with a needle and thread into the hole of thin copper wire. Rinse blanks, clean gasoline and tooth powder, again rinse and hold it in suspension or with tweezers, dip half a minute in dilute, approximately 5%solution of nitric acid. Finally, rinse in running water and hang on a metal rod. The suspension will drop into the Cup with two copper plates as anodes (the icons will cathodes). The pieces of foil should be located on different levels, so they do not obstruct each other. In a glass pour the electrolyte: 25 g of copper sulphate and 1.5 ml of sulfuric acid to 100 ml of water, preferably distilled. The power source is a battery; you can use a transformer with a rectifier. The current in the circuit is about 10 mA per 1 cm2. The thickness of the copper layer should be 0,5-0,8 mm

When copper plating is finished, rinse the parts. If you decided to do on the icon relief image or label, mark them with a needle. The portion of the surface, which coating is not necessary, close thin layer of glue BF, varnish or wax, dip the pieces into the electrolyte and again turn on the current to the exposed areas was covered by a layer of copper is then they will become convex. Then glue or paraffin clear.

If you can engrave on the icon or label image, and be sure to solder on the reverse side of the pin.

Finally, make the icon look elegant. Chemical paint and plating is quite suitable. But even better look icons under the old silver.

Prepare a 2-3%solution of silver nitrate (can be dissolved in water pharmacy lyapisny pencil). Small portions, add hydrochloric acid - 3-4 volume one volume of solution. With loose precipitate of silver chloride drain the solution, the precipitate several times rinse with distilled water, leaking water very carefully, on a glass rod, so as not to waste silver chloride. To the washed precipitate, add small portions of 30 %potassium iodide solution up until the precipitate has dissolved completely. Add water to bring the volume of the solution up to the original. You should have the same amount of electrolyte for silver, how you cooked it for copper plating.

In this electrolyte immerse icons (they will again be cathodes). Anodes can serve as graphite rods, better batteries, instead of pencils, because of their size should be a little more square icons. The current density is small, about 1 mA/cm2.

So on the icons is formed a layer of silver and, of course, it looks like new. But not so the trick to black icons under the old silver... Aqueous solution of potassium sulfide approximately 0.5-1%concentration, heat to 50°C. the Icons in this solution gradually change color - they will become the first grey, then blue and finally black. Rinse the icons and RUB them with felt or sukonkoj. Then the convex part will brighten, the rest of the surface will remain black, and the icons will look exactly as the product of old silver.

O. Holguín. "Experiments without explosions"
M., "Chemistry", 1986

 

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