Trade and Registration Marks
The pressed glass industry was very competitive and once a range or style of glass was popular with the public, all the other glass houses tried to replicate the designs to cash in on the success. Naturally this annoyed many of the large manufacturers like Sowerby and Davidson, so they started to register their designs, which were then impressed with registration lozenges or numbers.
They also patented techniques of making the glass and the glass mixes when making colours. Davidson patented their very successful Pearline range, but that didn't stop Greener, Sowerby and Burtles and Tate from making their own Pearline colour mixes.
For a collector, one of the most fascinating things about pressed glass, is that you can find out the precise date that the design was registered.
These were pressed in the inside/underside of the item, where it stood out against the plain background, without disrupting the pattern (although Davidson used to incorporate the trade mark in the centre of the pattern at the base of some items). Only five glassworks used to trademarks, with only two that is known to have actually registered the trademark.
The Designs Act of 1842, provided a 3 year protection period to stop other manufacturers from stealing designs. In 1850 the Act allowed a period of one year for provisional registrations. This appeared as a lozenge shaped mark with details of the class of registration - pressed glass was III, the day, month, year of the registration with the number of the bundle; with these details the name and address of the firm was also registered. Manufacturers were required to provide sketches of the designs, and some even used photographs such as Greener and Heppel.
There were two cycles of the lozenge marks. From 1842 to 1867 and from 1868 to 1883, with the positions of the numbers and letters changed to differentiate the cycle. At the top of the lozenge, if there is a letter then it is denoting a year and from the first cycle. If there is a number at the top of the lozenge, like the Sowerby example on the left then it is the date of the registration and is from the second cycle.
In 1883, the Patents Design and Trade Marks Act amalgamated all the categories/class and designs into one series which is identified as Rd No. then the number.
When collecting glass the mark can be hidden by dirt or the pattern, so rub your finger around the area to see if there are any marks. Also check under price labels, when I first started to collect glass I bought a piece that was called a "Victorian salt dish" only to find under the label that it said Avon. You only make mistakes like this once!
From 1909 paper labels were used, such as this Davidson label. Unfortunately as people either peeled or washed off the labels this meant that many do not exist any more. If you have any glass with labels on them, do not peel them off or soak the glass as it will slightly increase the value of the glass
The patents that were applied regarding pressed glass, tended concentrate on the new ways of creating moulds, mechanisms for pressing glass, finishing processes and the invention of new colours. Sowerby was the most active when it came to patents applying for 22 between 1870 and 1900. They were granted several patents for improvements for fire polishing, steam controlled pressing machines and colours including Queen's Ivory, aesthetic green, tortoiseshell and rubine. Despite Sowerby's efforts, people know more about the patents that Davidson applied for. Out of the five patents they made, the most popular was the technique of how to make Pearline glass 7 December 1889 and the flower block or dome in 1910, many of which are often found today complete with registration mark.