Rye flour paste is the traditional method used by moonshiners to seal seams on copper moonshine stills.
If a still has not been sealed properly, vapor will escape from the joint. Alcohol vapor is explosive at high concentrations. So, always seal your still and never distill indoors.
Once the boiler reaches 115 degrees apply the flour paste to the still
As the still heats up the rye flour paste will cook onto the still creating a seal at the joint
Keep an eye on your still to make sure that alcohol vapor is not escaping from any joint. Re-apply paste if needed.