While there is abundant information on Thonet furniture available on the internet in German as well as a few other languages, there seems to be a lack of English sources. I therefore decided to publish a translated and updated version of my very first blog post on how to identify Thonet furniture. While this article will help you tell apart a real Thonet from its many competitors, you might still wonder which exact model you are holding in your hands. To answer this question feel free to browse through my other articles (in German) or to send an e-mail to firstname.lastname@example.org.
Luckily, there is not only a large number Thonet catalogues that survived the ravages of time, which now serve as an excellent source of reference, but the Thonet Brothers were also very rigorous when it comes to hallmarking their products. If no label or stamp can be found on a chair, the probability is high that it was not made by Thonet. However, it is not uncommon that early chairs, which were still made from at least partially laminated wood, bear no hallmarks at hall. This can also be true for other pieces of large or very small furniture that were manufactured later, such as tables, rocking chairs or doll funiture. It is of course also possible that labels get lost over time, due to restauration etc., which is why it makes sense to always look at a number of specific constructional details as well.
The information contained in this blog post comes partially from my own observation and primarily from the literature that is available in German.
On its very early chairs Thonet used stamps that were embossed into the bottom of the seat frame. Stamps such as “Thonet Wien Gump. 396”, “Thonet Wien”, “GB. Thonet Wien” or “GT” can be found on these. While the former was used on chairs that were still made from laminated wood, the others can primarily be found on partially or fully massive furniture.
Much later, Thonet used stamps that can often be found in combination with one of the paper labels (see below). These stamps can be found in natural as well as black and white colour.
Thonet started to use paper labels at the beginning of the 1860’s. The first label, which was used until 1881, has three variants, called label 1a, 1b and 1c. These can be distinguished by the way in which the curls are crossing each other, as well as the thickness of the print. Label 1a was used between 1861 and 1870, label 1b and 1c between 1870 and 1881.
Between 1881 and 1919 Thonet applied the second version of the paper label, which also makes it the most commonly used. There are a number of variants such as for the Hungarian (“TT” instead of “GT” for „Thonet Testvérek“) or the Russian market. Moreover, special labels with a completely different design exist, such as for the French market.
After World War I, Thonet started to use a simplified version of its label, which no linger made reference to Vienna and only included a T instead of GT in the ornament.
Black stamps on a plate
Around 1880 Thonet started to mark its chairs with a black stamp „Thonet”, later “Thonet Austria”, that was placed on top of a plate cut from the seat frame. The first plate had a diameter of 40mm and was later enlarged to 62mm. Sometimes the stamp can be found in combination with numbers, whose prupose is still unknown.
Letters and other stamps (symbols, numbers etc.)
It is quite common to find letters and other symbols embossed on the bottom of the seat frame of early chairs. According to a common theory, the letters indicate the factory in which the chair was manufactured (e.g. K=Koritschan, B=Bistriz, W=Westin). However, there seems to be no reliable evidence to support this view. Moreover, Arabic or Roman letters can be found on some chairs. These most likely were meant are to help with the assembly of matching parts, e.g. when several chairs were shipped as parts in one container.
Selected constructional details
If no labels or stamps can be found, it is sometimes still possible to identify a chair manufactured by Thonet. Some early chairs have legs that are drilled through the seat frame. This detail can however also be found on chairs by other, less known manufacturers and therefore only serve as an indication.
Another sign are the braces that buyers could order as an option for their chairs or that were a standard feature on some chairs starting around 1875. On Thonet chairs these are usually flush with the seat frame, this is however not necessarily the case with later makes.
There are of course many other details that help to tell apart a genuine Thonet from one of its competitors such as the construction of the seat frame (laminated, three layers, enforcements etc.) as well as stylistic aspects such as the capitals and overall appearance. These however only provide a certain level of certainty, which is why there are not described here. I am however happy to answer any remaining questions via e-mail (see contact details baove).
See e.g. Von Vegesack – „Das Thonet Buch“; Ottillinger – „Gebrüder Thonet“.
 Ottilinger, p. 109.
 Ottilinger 114 f.
 Source: Wienermöbel.ch