Using physical, manufacturing related diagnostic features, most utilitarian bottles can usually only be accurately placed within a date range of 10-15 years (i.e., 1870-1880 or 1885) . Like many industries making the leap from manual craftsman production to industrialization and automation, technological advances in bottle manufacturing were not immediately accepted by glass manufacturers or their workers.Acceptance often occurred over a period of many years or decades in some cases.Use the larger number if there appears to be two different serial numbers on your machine.
A substantial amount of bottle type specific information must be reviewed by a user to increase the probability of dating accuracy.
But any technique, once developed, can be used right up to the present - as many collectors know who have been so unfortunate as to rely too heavily on a popular termination date as sure evidence of true antiquity..." (Toulouse 1969b).
In short, there was (and is) nothing to stop a glassmaker from using an obsolete method in the production of a bottle.3.
On some of the older models, which might have the brand name painted onto the finish of the machine, the lettering might be too scratched or faded to read.
Consequently, you may have to try to use the model and serial numbers as you go through the process of dating the machine. The serial number will not be the same as the model number.