A Recipe to Make Your Own Natural Rosin Soldering Flux
To provide a safer alternative to the chemical-laden stuff, catsndogs came up with a recipe for rosin flux that uses natural ingredients.
Soldering is likely the most common skill among makers. With the exception of some basic components that fit together with special connectors, almost every electronic project requires at least some soldering. Most people start with a soldering iron and through-hole components, then move onto more advanced hot air soldering with SMD (surface-mount device) components as needed. Rosin flux comes in handy for both types of soldering, but the chemicals in commercial rosin flux can cause health problems. To provide a safer alternative, catsndogs came up with a recipe for rosin flux that uses natural ingredients.
Hopefully you’ve already stopped using lead solder, but your rosin flux may still be dangerous. Different formulas exist, but typical rosin flux contains several chemicals that may be toxic. Reports on the dangers vary, but exposure to rosin flux fumes can irritate the nose, sinus, eyes, throat and skin in the short term. Long term exposure may even result in asthma or dermatitis. It may be possible to reduce those symptoms by using natural ingredients. The chemicals in commercial rosin flux exist to either lower costs or improve performance, but aren’t completely necessary.
This recipe calls for pine resin. You can collect that yourself if you have pine trees nearby or you can buy rosin from a music shop. With either, the goal is to refine and filter the substance to produce clean rosin flux of the desired consistency. You can achieve that by mixing in alcohol (many different types work, including standard rubbing alcohol) to lower the viscosity enough to strain the resin through a coffee filter into a clean glass jar. Repeat that process until you have nice, clean resin that is free of particulates. Then either add alcohol or let the alcohol evaporate until you reach the desired consistency. Sealing the jar will retain that consistency.
When you’re ready to use the rosin flux, you can either apply it with a brush dipped in the jar or with a large gauge syringe. When you’re done soldering, alcohol will clean the resin right off the PCB. Rosin flux helps you produce good solder joints, so this recipe lets you continue to do that with less risk to your health.