Topic: Victorian glass density values (Midlands makers)

[tropdevin]

I am trying to find out more about the density (or specific gravity SG) of the glass used by various manufacturers in the Midlands area in the 1840 - 1900 period.  My reason is to try and track down the probable makers of a couple of designs of paperweight.

I have measured the SG of over 150 Old English paperweights in the last couple of years, and know the typical ranges of SG for paperweights believed to be made by Richardson, Arculus / Walsh Walsh (1900 onwards), Bacchus, Islington (and also 1950-1970 Whitefriars).  I have measured a couple of Richardson family bequest items in Broadfield House, and these are consistent in value with their paperweights.

I have seen some SG figures for uranium glass published by Barrie Skelcher in 1998, but those are the only public domain measurements I have managed to track down.

Does anyone know of published SG measurements for Midlands manufacturers pieces made 1840-1900, particularly from the following:

George Bacchus & Sons
Webb & Sons
Joseph Webb
Osler
Chance
Stevens & Williams
John Walsh Walsh
Davis, Greathead & Green
Thomas Hawkes
Hodgetts, Richardson
Rice Harris / Islington
Boulton & Mills

Any help gladly received!

Alan

[Frank]

Try the Society of Glass Technology.

But it is unwise to assume the same formulations were used for all types of glassware produced, or throughout such a long period.

[tropdevin]

Hi Frank

Thanks for the suggestion.

I was not intending to imply that there was a single glass mix in any particular factory (what is probably most relevant to my research is clear lead crystal glass); or that it remained constant throughout the period I have defined (I think there was a tendency in some firms to reduce the amount of lead as financial pressure increased); - or indeed that the batch was the same day to day(as a shovel full too many or too few of some ingredient went into the batch by mistake)!

But any information would be helpful - the measurements I have made to date do show that useful information can sometimes be obtained from measuring the SG.

Alan

[Frank]

Googling gave one surprising result:

Glass - broken or cullet	1290-1940 kg per cubic metre
Glass, window	2579 kg per cubic metre

http://www.simetric.co.uk/si_materials.htm

and

Glass min.	2.4
Glass max.	2.8
Glass crystal min.	2.9
Glass crystal max.	3
Glass plate min.	2.45
Glass plate max.	2.72

http://www.postdiluvian.org/~mason/materials/specific-gravity.html

Then

http://links.jstor.org/sici?sici=0885-2731(194901%2F02)39%3A5%3C684%3ATVWRTT%3E2.0.CO%3B2-%23