A riveted copper pot is beautiful to look at and will give you many years of enjoyable distilling hours.
However, as copper contracts and expands quite a lot with temperature changes it sometimes (but seldom) may cause leaking around seams and copper riveted joins that have not been soldered.
Three ways of sealing the leak:
1. The traditional way:
To fix this leaking is fairly easy and the sealing technique has been used for a few hundred years to seal pots with no leakage through even the tiniest openings caused by copper expansion/contraction. You wil note that all new rivited copper pots do have a "sealant paste" on the inside of the pot. It is completely inert and should not be removed. If you accidentally removed it and your pot starts leaking, stop the leaking as follows:
Make a thick paste (to brush on) with:
- Gypsum chalk (finely ground into a powder) or even plaster of paris.
- Linseed oil
At some gypsum chalk into a small container and add a little linseed oil. Mix well until it becomes a smooth but thick paste.
Clean the inside of the copper pot along the join line with clean alcohol. There is no need to remove the old sealant.
This "sealant putty" can now be painted on the INSIDE of the still where the leaking occur.
Leave it to dry for at least 72 hours and the "painted putty" will form an excellent inert seal. Little pieces that might come off during distillation will be discarded with the stillage after distillation.
If the putty does not want to dry, heat the copper pot slightly (to about 65C) for a few hours to speed up the chemical process to cure the putty.
A seal like this will last quite some time (years) and if necessary, just paint over it in the event that it starts leaking again.
An interesting fact: This putty made with linseed oil and gypsum powder, was also used to glaze windows. The most famous example being in the home of the original Kennedy family in the US. The putty used in their windows are painted with linseed oil every five years and today, after a quite a few generations, the putty is still flexible and seals superb. No other caulking sealant (including silicone) has yet been manufactured that has proven itself as good as this putty recipe!
2. A bit faster:
If, for whatever reason it is leaking (very rarely) along the rivited joins, you may try the following: Fill your still with clean water to about 50mm above the riveted join. Then add about 40g rye flour per liter water in the pot (available from health shops) and bring it to boil while stirring. The Rye flour will seal even the smallest leak. After this "sealing boil", do another one or two pure water distillations to get rid of the "rye" taste and thereafter us it as normal. You may also try the seam sealing recipe to produce watertight joins between riveted joins.
3. The permanent way:
...and off-course you may solder the leaing area with lead-less 97/3 solder (available at all harfware stores - ask for solder to solder drinking water copper pipes)