Top End Considerations
The Top End
The top end of the distillation apparatus is the most important part of the still. It consists of a reflux column, one or more condensing elements, and a mechanism to control the amount of distillate returned to the column as reflux.
The design and construction of the top end will ultimately determine the measure of the still's capability.
In this guide you there are two different top end designs presented.
One provides the reflux control by regulation of cooling tubes within the column. This model will be referred to as the Internal Reflux model.
The second still has valves to regulate the reflux. This still will subsequently be referred to in this guide as the Valved Reflux model.
Each design has its own advantages and detractions. These will be explained as we get further into the construction and operation sections.
Top End Materials
It seems natural that a stainless steel boiler should have a stainless steel top end. That would not only look nice but it is also easy to clean, rustproof, and extremely durable.
Here's a picture of what an all stainless steel Internal Reflux still looks like.
This beautiful example was built by Ian Pilcher, a master Australian craftsman, and serious distiller.
But for the rest of us less talented people though, dairy or medical grade stainless tubing and fittings are not easy to find and the parts are horrendously expensive. A small ½" stainless coupling costs as much as $36.00 USD. Regardless of these costs, you will find most of the suppliers will not want to deal with you on such small orders.
The automotive supply stores offer stainless steel T409 automotive exhaust pipe. And while it is less expensive (about $10.00/Foot), it takes a lot of polishing to make it look good, and because there are limited fittings available, this kind of tubing needs extensive welding to fabricate it.
Glass is also a nice material to build a a laboratory still with, but it is very costly, very fragile, and requires expensive custom glassblowing services to complete the fabrication. And while it may be just the thing for small distillations in the laboratory, it is impractical for multi-gallon distillation in the harsh environment of a garage or outdoors.
I've heard of some stills which were made with ABS or PVC plastic piping. These materials are not recommended for this type of still. They are not suitable for containing vapors at high temperatures, and may pollute the distillate.
So what you build the top end with will probably come down to what is available where you live. If you live in the US, and you want to build a still at home , most likely plain old copper tubing will be your best choice.
It’s easy to cut, silver braze, and solder. There are an endless number of standard fittings available at plumbing supply distributors, a wide variety of tubing sizes, it is quite inexpensive (around $1.00-$3.00/ft.) and it really looks beautiful when polished. Some even say it gives character to the flavor of the spirits too.
(Packed reflux column with internally controlled reflux)
For those reasons, the rest of this guide will focus on building a hybrid still with two choices of stainless steel boilers, and two choices of copper tubing top ends. You can mix and match any of the four combinations to suit your needs.