vac pots
Otto Schott was a German chemist who developed borosilicate - heat resistant glass that is essential for making vacuum coffee makers that last. As a matter of fact, Jenaer Glas, the household division of the Schott company, made their own vac pots - the Sintrax.

Schott, Sintrax, and the Bauhaus connection

The earliest Jenaer Glas vacuum brewers must have been traditional designs, based on a technical filter appliance for chemical laboratories.
In 1925 (some sources say 1923), Gerhard Marcks - a pioneer of the Bauhaus school in Weimar- redesigned this product for use on gas stoves, or electric heating plates. Unfortunately, I don't have any pictures of either the earliest versions, or of the Sintrax as designed by Marcks.

The designed remained the same for some time, until in the early 1930's Wilhelm Wagenfeld joined the Schott company. Apart from a wide range of household glassware, including an all glass tea-set with his famous, and very beautiful teapot, Wagenfeld also "redesigned" the Sintrax coffeemaker, by giving it a new straight wooden handle. The reason was actually a rather practical issue - the original design by Marcks featured an angled handle that often got burned when used on a gas stove. Wagenfeld's solution was simple: make it a straight handle. Although Wagenfeld is often named as the designer of the Sintrax he really only created the handle:

Pre-war Sintrax

This type of Sintrax was available in 3 sizes - 0.5, 1.0 and 1.5 liter. They're relatively hard to find items, and often go for insane prices. Mine is the one liter model, but it has the same funnel as the 1.5 liter size - all parts are still original, and the vac pot is in near mint shape. As you can see, the Sintrax has some interesting features. Like the Cona's the design is almost all glass, including the filter, the lid for the funnel, and the stopper for the jug. The filter is an odd contraption; a sort of a glass sieve.

Pre-war Sintrax - parts

These Sintraxes were produced until the beginning of 1938. At some point in time, the Jena co. released an electric stove to go with their vac pot, I have no date here, nor a name of its designer.

After the war

Production of the Sintrax was resumed some time after World War II - presumably 1948, or thereabouts. These "new" models can be identified by the "Schott & Gen. - Mainz" logo, as opposed to the indication "Schott & Gen. - Jena" on the pre-war models.

The new model is more smoothly curved, and IMO far more elegant than its predecessor. It also got another handle, this time made of plastic, and angled again. The post-war Sintraxes were available in a number of sizes, ranging from liters to 1.5 liters. The ones I have are the 1 liter, and the liter model:

Post-war Sintrax

The most striking difference between the old Sintrax, and its successor is the gasket - or rather, the lack of one. There is no rubber sealing part of any kind. This feature is clearest in the picture below:

Post-war Sintrax - parts

As you can see the rim of the jug, and the mating part on the funnel are ground glass (which looks very much like 'frosted' glass). The ground glass itself does not form anything like a decent seal, but water held between both parts sort of works as a seal - albeit slightly sensitive to irregular boiling.
In 1960 the final curtain fell for the Sintrax coffeemaker.

After all this history, you may be curious as to how it actually performs. Can it make a good cup of coffee?

The answer is: yes, it can.

Yes, it can, but not without some hassle, and occasionally, disappointment.
If both sides are properly wetted, and the water is distributed evenly, the gasketless design can be said to work ok at best. The glass "mesh" filter isn't too good either. One will need to grind rather coarsely, and even then it will let quite a bit of finer particles get through. To get a good brew with the coarse grind, and also to get a decent vacuum to get that brew downstairs at the end of the ride, you'll need to let it boil for quite some time - maybe up to five minutes.
A third downside is the amount of water left in the jug when brewing, which will dillute your coffee far too much, unless you use the vac pot at full capacity.
Last point is the hassle of cleaning - it's almost impossible to remove the last grinds stuck in the filter, and the area underneath it can't be reached at all.

If you're just looking for a good every day brewer, this is not going to be the one you're going to like best. To be honest, even the Bodum Santos would be a better, and probably much cheaper choice.
On the other hand, although the Sintrax may not be the greatest vacuum pot you can find, it is definitely one of the most elegant glass siphon brewers ever made, and this is the reason I have a special fondness for the gasketless series. (So if anyone has one of these cluttering their kitchen, and gathering dust - you know where to find a warm, and caring home for it - just drop me a line.)

Sintrax style vac pots

There is little information about the Roki, another 1930s vac pot that occasionally props up on auctions, usually wrongly using the name Sintrax. Although it resembles the Jenaer vac pot, and was probably styled after it, there are some distinct differences. (If I can get a picture of a Roki, I'll see if I can put it up soon.)
For one thing, the Roki has a different handle - resembling a Cona stand bend an odd shape. Also, these vac pots have a cloth filter, much like the Hellem vac pots.

I've been told that other coffee makers resembling the Sintrax' were sold in department stores in the early 1990s - at least in Australia. These had plastic filters discs like to those found in the Bodum Santos. They had disappeared by 1994, probably due to lack of sales. Unfortunately, I've very little information on these - I don't know whether these were in fact made by Schott, or by an Asian (?) company, possibly under license.

With thanks to the Schott company for providing some of the historic information presented herein.

Curious? Want to know more? Ask!