The Compleat Distiller

THE COMPLEAT DISTILLER 81
Sealing large containers
One of the most difficult jobs anyone can face is to provide a good, gas-tight seal for a lid on a large
container like a boiler.
You can buy excellent "band" clamps with matching seals, just like those used for stainless steel
couplings, and they offer a quick and effective solution, but are not available everywhere. What are the
alternatives?
Home made seals or gaskets
The first step in sealing a pot is to make an effective gasket for the lid. You are very unlikely to find a
ready-made seal just the right size or shape. It used to be that the only solution was to make a flat
gasket out of paper, rubber or soft metal, or to resort to crude (but effective) measures like flour paste.
Today, Room Temperature Vulcanizing (RTV) silicone sealants are readily available, and they make
the job very easy. These sealants are often intended for outdoor use, and may contain toxic chemicals.
You want the kind marked “acceptable for food contact” or "aquarium grade", which is clear and not
colored.
To make an RTV gasket for a pot, first clean the mating surfaces with acetone to remove all traces of
grease or oil. Smear the top edge of the pot with petroleum jelly, and apply RTV liberally to the outer
edge of the lid. Put the lid firmly on top of the pot and wait for the sealant to cure (24 hours is best).
This makes an excellent, semi-permanent seal that remains attached to the lid. Of course, by choosing
where you put the petroleum grease, you can make it stick to the pot, or make it so it comes free as a
separate item. Since the sealant is rather weak by itself, we recommend leaving it permanently
attached to a strong surface. If it ever becomes damaged, it can be removed with a razor blade.
Clamps
Now that you have a gasket, the lid needs to be
securely clamped to the pot, especially if it is also
supporting a long top-heavy column, which could
easily topple over.
Fig. 7-10
You can rivet brackets onto the sides of the pot, and
use these to secure clamps that hold the lid on, but you
have to make sure that the rivets don't cause more
problems than they solve. Solid rivets used to be
common, and good kitchenware still uses them.
Modern "pop" rivets will hold the brackets firmly in
place, but are unfortunately hollow and not gas-tight.
If you do choose to use them, plug the holes through
the rivets with self-tapping screws.
If the pot comes with handles, then all your troubles are over! You can easily make the sort of clamp
that is used to secure inspection hatches onto whiskey stills. This clamp is simply a bar (or shaped
plate) that crosses over the top of the lid and which, when screwed down using the handles as anchor
points, presses the lid down firmly and evenly onto the top of the pot. No handles? Rivet or braze on
your own supporting handles or brackets!