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Will the Lead Free Solder on a Copper Still Melt When Heated with a Propane Burner?
We get a few emails each week asking this same question. The short answer is no. Heating a still on a propane burner, fire, or an electric hot plate will not melt the solder on a still. The long answer is that every brand of lead free solder should have a melting point between 420 and 460 degrees. When distilling alcohol it is important to know that there will always be liquid in the still. There is not a point in the distillation process when the still will not have liquid in it. If starting with 10 gallons of wash by the end of distillation there will be around 6 gallons of liquid left in the still.
The process of distillation concentrates the available alcohol in the wash. At the end of the run the majority of the alcohol will have been extracted from the wash. The leftover liquid in the still is going to be mostly water with a very low percentage of alcohol. The small amount of alcohol that remains in the still is not worth the time or energy to extract.
The melting point of lead free solder is between 420-460 degrees, there will always be liquid in the still, and water boils at 212 degrees. Since the still always will have liquid in it, the still won't get above 212 degrees. Since the melting point of solder is between 420-460 degrees we can safely say that the lead free solder will not melt.
The only way to melt the solder on a copper still is to "dry fire", or to heat the still without liquid in it. If a still is heated without liquid it will easily get above 460 degrees. This will easily melt the solder and damage the copper still. It is very important to make sure that the copper still is leak free and water tight before distilling. If a leak is noticed always turn off the heat source, empty the still, and repair the leak before continuing.
Even though a fire or a propane burner won't melt the solder on a copper still we always recommend using an electric heat source instead. There are a few reasons we prefer electric:
- It is easier to regulate the amount of heat being applied to the still with an electric heat source. It is possible to fine tune the electric output to get the perfect amount of heat on the still. It is a lot more difficult to dial in the exact amount of heat needed with a propane burner.
- It is safer to use electric because there is not an open flame as there is with a propane burner. If an issue arises during distillation and explosive alcohol vapor is escaping from the still it is safer to not have an open flame.
Always check the label on the solder to verify the melting point, that it is lead free, and that it meets the requirements of the Safe Drinking Water Act.
**Always use lead FREE solder and water soluble flux when assembling a copper still kit**