We will need:
- Model wax.
- Fireproof gypsum.
- Silicone.
- Tubes of different diameters.
- Wax cutters (several knives).
- Soldering iron.
- Gas-burner.
- Wire with a diameter of about 1.5 mm.
- Boric acid.
- Lemon acid.
- Titanium spoke.
This is the most important thing; some other little things will come in handy as production progresses.
Wax model
So, it all starts with making a model of the future product. For this purpose, hard jewelry wax is used. I recommend using red, as it best shows the small details on the model. I tried to replace it with regular wax, paraffin, even hot glue, and it’s still not clear what. So, all this is nonsense, buy jewelry wax, since only this is suitable for normal work! I purchased a small quantity from China for just a few castings.
To make a ring, you need to find a tube of suitable diameter. Wrap a thread or strip of paper around your finger and determine the circumference. To do this, I offer a table of ring sizes.
We wrap foil around the tube to remove the wax later. And now we cut the wax into small pieces and fuse them onto the tube. Here we picked up a soldering iron and will not put it away soon. The idea is that we form a "ring" of wax on the foil on the tube. We completely fuse the pieces together, not just the edges.
And now comes the process of wax carving and shaping the future product. For this I used small thin knives and needle files. In general, the whole process can be characterized as follows: we remove and cut off everything unnecessary. The wax cannot be cut, it must be scraped off with a blade and a file.
Once the wax is ready, it can be duplicated an unlimited number of times using a silicone mold. Using the same method, you can copy ready-made rings. To do this, place the wax, or some kind of ring, without removing it from the tube, in plasticine formwork and fill it with injection molded silicone. Yeah, injection molded, well, here you can go on a farm and use silicone sealant.
When the silicone hardens, you can remove the tube and wax from it, then cut the mold from the side. Now you can use the same soldering iron to melt pieces of wax into it and get exact copies. This is very convenient, even if you are making a single product, it is worth making a silicone mold, especially if the wax is difficult to repeat. Personally, I was able to properly cast the model only the fourth time.
Plaster mold
Now we attach the sprues to the wax - wire with a diameter of about 1.5 mm, but no more, later you will understand why.To do this, you can add a little wax at the sprue attachment point, and also heat the wire and insert it into the ring. Next, we fix the model on a hemisphere made of plasticine. The sprues should not be made too long or thin. Also, for proper metal casting, it is necessary to connect the sprues together with the same wax. You can also place two models in one plaster mold.
Now plaster. For these purposes, special refractory gypsum with an admixture of quartz flour is used. We farm again and use the usual one. If you don’t have a goal to become a professional jeweler, and just want to cast one or two models, then you can deviate a little from technology from time to time.
We wash the wax with alcohol tincture from the pharmacy, soapy water and plain water.
We also take a pipe with a diameter of about 4-5 cm, cover it with wax and fill it with plaster. It sounds simple, but the plaster must be mixed in proportion; it hardens quickly (5-15 minutes), so stir quickly too; and most importantly, all air bubbles must be removed from it. For this you need a vibrating table, preferably with a vacuum chamber. In general, this is not difficult to make, but do we really need it?
The wax can be coated with plaster with a brush, and then poured into a pipe, but here the strength is lost. I don't do this and prefer the strength of the plaster mold.
When the plaster has hardened, take out the plasticine and sprues; need to get rid of the wax. You can use a water bath, which is correct, and the wax can be collected and used again. But I'm missing it. Since, in any case, the plaster mold must be calcined to remove all moisture. I used the stove at the dacha for this. And it burned for about 2 or 3 hours, I still drown when I’m there.Again, a step away from professional technology, but it works, and all the wax burns out.
Casting
Let's get ready first. We put regular toilet paper in the cup and wet it so that when pressed with our fingers, the water no longer flows freely, but the bottom should still be quite wet. And a titanium knitting needle is needed to mix molten metal, which will not oxidize, except perhaps with titanium. We start by heating the flask with a burner.
Scrap silver is used for casting; I melted down the broken chains. We throw them into that hemisphere and start heating them with a burner. When the metal begins to turn red, add a little boric acid, this is a flux that prevents silver from oxidizing; it generally does not like oxygen in the molten state. The silver is fused into a drop and, due to surface tension, does not flow into the sprues. When the silver has warmed up as much as possible, cover the flask with a cup and press down. The water from the toilet paper boils and presses the metal into the sprues. Then we take out the product.
Processing and polishing
We bite off or file off the sprues and heat the product until red hot and dip it in a citric acid solution to relieve residual stress. And boil this solution. Boiling citric acid works like a real acid and eats away all the slag.
Now the workpiece can be processed with sandpaper. We start with a rough 600 and move towards increasing the grain, I reach 2500. And then we polish with GOI paste.
That's all, you can cast any jewelry this way. In the article I paid more attention to wax and casting, and only briefly talked about processing, since there is nothing complicated or tricky about it.
