A fundamental when it comes to welding stainless steel or another high nickel alloy is having something on the back of the weld. This is essential to keep oxygen out and dissipating the heat. If you fail to protect the back of the weld will result in a burn through weld that is sugary and porous.
These properties in your weld are far from ideal, but can be easily avoided with correct backing. Either purging using a inert gas such as argon or the use of Solar Flux is most commonly used. Solar Flux is an extremely fi ne powered, finer than even talcum powered. When this is mixed with alcohol it is suffi cient to block out any oxygen.
The first step in the process of using Solar Flux is to create the substance you will need. You will need to add alcohol or methyl alcohol to the powered to create a consistence similar to cream. You should only mix what you need for the job as the alcohol will evaporate.
Once the mixture has stood for a couple of minutes allowing the chemical reaction to take place, it is time to apply to your welding seem. Using a small brush apply around ¼ inch to the back of the joint on either side. Leaving this a few minutes while the alcohol evaporates, then weld as normal.
After the weld has been complete the Solar Flux will leave a glass like residue on the back. This doesn’t need to be removed but can be unsightly and is easy enough to remove using a stainless steel brush or pickling compounds.