Soldering gold objects together, or repairing gold by welding, requires a slightly different approach than working with lead. Even if you have good experience in welding with other metals, you should still read the tutorial to find out what materials and tools you will need and learn which filler material, which torch and which flux is best to use for this job. It is a high temperature soldering, which is technically called "brazing", which is not easy to make. For all of these reasons, you should start with less precious metals and items that don't have sentimental value.
Steps
Part 1 of 2: Getting the Materials
Step 1. Use any type of firebrick
This stand is designed to prevent heat loss and withstands high temperatures. The bricks that are used to build the ovens, the blocks of magnesia or those of coal are among the most used.
Step 2. Buy a filler material for gold
Any metal alloy designed to melt and join other metals is called "solder" or filler material. However, most alloys are not effective with gold. You can purchase a special solder that is sold in wire, sheet or 1mm pellet. It is worth cutting large pieces of filler material into small pellets to do a precise job, and at the same time controlling the amount of material applied.
- A filler material with a high gold content is stronger and requires a lot of heat to melt. This is especially recommended for joining two pieces. Use a "lead" alloy with a "medium" or "high" melting point, or a material of at least 14 carats.
- Solders with a low gold content melt more easily and are suitable for small repairs. Choose a "repair", "low melting point" or less than 14 carat product.
- Check the label before buying a filler material for rose gold, as it may contain cadmium (which is very toxic).
Step 3. Choose a precision soldering torch to melt the solder
A small oxyacetylene torch is a good solution, but butane or high temperature ones are also suitable. Electric soldering irons are not recommended for processing precious metals and other projects where high temperatures are required.
Step 4. Find the right flux
Before welding gold, just like other materials, you need to get a chemical product called "flux", which is applied to clean the surface of the metal and facilitate the process. Get a flux that is safe for gold at a hardware store or a shop specializing in repairs of precious materials. Sometimes you find it under the name of "brazing flux", which indicates that it is suitable for high temperatures. This product is available in liquid form, as a paste or in powder form to be mixed with water to create a dough.
Although brazing is technically a different procedure from welding, even jewelers use the expression "solder gold" instead of "solder". A flux that says "solder flux" might be fine, but check the label to make sure it is suitable for gold
Step 5. Ensure good air circulation in the work area
Use a fan or open the window to create a gentle breeze in the room where you have decided to weld - this will remove any toxic fumes from your body. If the air flow is too strong, it could interfere with the welding and make it more difficult, since it cools the materials.
Step 6. Buy some copper pliers and all the tools to hold the piece of gold in place
Copper does not react with the acidic pickling solution that will be described below, unlike steel. You will also need a tool that holds the piece to be welded in place, such as tweezers. You can also use clamps or a table vise, but do not tighten them too hard to avoid denting the gold.
The pliers or clamps do not necessarily have to be copper
Step 7. Follow the safety instructions
Goggles are a vital device to keep splashes of molten material from getting into your eyes. A wide welding apron is also recommended so as not to burn clothes. Roll up the long sleeves and tie your hair into a ponytail as an added precaution.
Step 8. Prepare a bowl of water and a bowl of pickling solution
The first will be used to cool and rinse the gold; the "pickling" solution is used instead to clean the oxidation residues from the metal: buy it and prepare it following the instructions on the package. Generally it is a powder product that must be dissolved in small quantities in water and heated.
- Never put this acid solution in steel containers or in contact with tools made with this material.
- Never heat the solution in the microwave or in a container that you will later use for cooking. The acid leaves an unpleasant odor and toxic residues.
Part 2 of 2: Soldering the Gold
Step 1. Thoroughly clean the metal
The surfaces to be joined must be clean and degreased, so that they bind chemically. Immerse the gold in the pickling solution for a few moments to remove all traces of contaminants, then rinse it in water to remove the acid. Scrub the surface with a detergent or soap for a deeper clean.
Some people neutralize the acid by putting bicarbonate in the rinse water, but this is not a mandatory step, unless the pickling solution is very strong
Step 2. Fix the gold in place
Place it on the block of refractory material and hold it in place with tweezers or a vise. The surfaces to be joined must be as close together as possible, as this process cannot fill very large gaps.
Step 3. Apply a small amount of flux to the areas to be soldered
This product removes residual impurities and prevents gold from getting stained. Apply it only where the soldering will take place to prevent the solder from invading the wrong surfaces. However, some prefer to spread the flux on the entire piece of gold to minimize the risk of stains.
Step 4. Slightly heat the flux
Use the torch to heat it slightly in the place where you applied it, wait for the water to evaporate and leave only a solid protective residue on the material. This residue avoids the formation of copper oxide. If you have spread the flux all over the gold object, heat it completely before adding the filler material.
Step 5. Apply some solder and heat
Place a solder pellet on one of the ends that need to be joined and heat the surrounding area. If you are using a torch adjusted to the right temperature, you should heat the metal enough to see the filler material that melts without the whole object becoming red-hot. Move the flame back and forth slowly as you apply the heat to heat the entire welding area. The filler material should melt along the gap that separates the two surfaces and joins them.
Step 6. Treat the solder spot with water and pickling solution
When the solder has penetrated the slot and the two surfaces have been welded, turn off the torch and wait for the gold to cool. After a couple of minutes, temper it in water. With copper tools, dip the gold slowly into the acid solution and wait for most of the stains and halos created by the fire to disappear.
Step 7. Make final changes if necessary
Remove the gold from the acid solution and rinse it with water, finally check it. It may be necessary to polish or file the excess filler material and the halos left by the flame, in order to obtain the look you want. The two gold pieces are now perfectly joined by a strong weld.
