Dating plastic tokens

[plasticman]

The 'fiber' mentioned by Peter is 'vulcanised fibre' made by converting cellulose fibre with zinc chloride to make a sheet material from which tokens, gaskets and even suitcases were made. Some transport tokens were made from them - listed in the Smith range of token catalogues where you can also find tokens in many plastic materials (and metal of course) from Celluloid to polystyrene, although most of them are just described as 'plastic'.

I understand that there is a report on the Ceylon coin in the National Archives at Kew, London. I shall view that next year !

Colin

[Figleaf]

I feel production method and material are clues to dating the tram/bus tokens and it looks like you know much more about plastics than me or Dustin Hoffman. Hoping you can enlighten me.

Peter

[plasticman]

Peter, you are correct in saying that material and method of production are indicators of date, but I wish it were easy ! Celluloid sheet was skived off a block (like making wooden veneer) and you can sometimes find parallel fine lines across the token surface - that's a giveaway and indicates pre 1940 and probably 1920s. Blank discs were cut out of the sheet and then stamped in matching dies. At the other end of the time spectrum, since the 1960s most tokens have been injection moulded which leaves a tell-tale edge mark where the molten material was injected into the closed mould - the sprue mark. Some softer tokens were injection moulded in cellulose acetate from the 30's to the 50's but most modern tokens are made from polystyrene. The trouble is that between the two world wars other plastic sheet materials were used with various stamping technologies.
An FTIR spectrophotometer with a good database is useful but not infallible !
Colin
p.s. For anyone that is puzzled by the Dustin Hoffman reference, think The Graduate 

[andyg]

this post (tucked away in the transport token section)

http://www.worldofcoins.eu/forum/index.php/topic,24184.msg159987.html#msg159987

explains the manufacture of some of these in the UK a little.

[Figleaf]

Thanks, andyg, I am thinking of fashioning a "token production" thread out of this fascinating material.

Plasticman, there are other clues for dating the tokens, such as denomination (decimal or pre-decimal), tariffs, lower government reforms, changing the name of regions and transport company history, so production method and material would fit right in there. Taking 1910 (thinking of Ilkeston) as the start of plastic tokens, what do you think of this table:

Approx. Period	Material	Clues and characteristics
1894-1940	Celluloid	Thick, parallel surface lines
1945-1960	Cellulose acetate	Thin, smooth surface, seam
1960-date	Polystyrene	Thin, sharp profile, seam & sprue

* Updated in view of comments below.

Where would vulcanised fiber and bakelite fit in? I am not seeking perfection, just a guide for the un-initiated.

Peter

[plasticman]

 Celluloid is incredibly inflammable and dangerous to use so when cellulose acetate sheet became available in the 20s it gradually replaced the cellulose nitrate but was still referred to as 'celluloid' hence some of the comments in the Priscilla Langridge piece. Few tokens were made from the original Bakelite material phenol formaldehyde because of colour restrictions but the colourable urea formaldehyde was extensively used in the 30s-50s
I shall ponder over this as I am away now for the next few days.
colin

[andyg]

Taking 1910 (thinking of Ilkeston)

There are some tokens of the "Glasgow Tramway & Omnibus Co." which ceased to exist (they became Glasgow corporation) in 1894

The British Museum has some from the Montague Guest collection, gifted in 1907 from Newcastle and Tynemouth.
http://www.britishmuseum.org/research/collection_online/collection_object_details.aspx?objectId=81498&partId=1&searchText=newcastle+corporation&page=1

Manchester's ½d and 1d were first issued September 1904.

[Kushi]

Not a few tramway and bus depots suffered serious damage when the stockpile of celluloid tokens in the offices caught fire.