Triplex Glass Manufacturing Date Codes

Triplex Glass Date Codes (prior to Jan 1969)

Cars made in the 1950’s to the late 1970’s can be dated by the ‘TRIPLEX CODE’ etched into the toughened glass. Note that it dates the GLASS, so is only an indication of the cars age, assuming the glass is original.

Year code

The year code can be found in the Nine letters make the word TOUGHENED. One dot below a letter gives the year of the decade:


  • T = 1
  • O = 2
  • U = 3
  • G = 4
  • H = 5
  • E = 6
  • N = 7
  • E = 8
  • D = 9
  • No dot = 0 (or possibly a dot under a space after the last letter)

This code also works if you have a TRIPLEX curved windscreen with the (also Nine letter) word LAMINATED instead of TOUGHENED.

Quarter code

To further determine the approximate month of production, just look for two dots in the TRIPLEX logo on the glass.


One dot above T, R, E, or X gives the quarter of the year the glass was manufactured:

  • T = Jan, Feb, March,
  • R = April, May, June,
  • E = July Aug, Sept,
  • X = Oct, Nov, Dec.

Example: say your car is from the 50’s, then TRIPLEX TOUGHENED, with one dot over the ‘R’ in Triplex, and the other under the last ‘E’ in Toughened, indicates ‘April/May/June 1958’

image        image

Date code 2nd quarter 1959              Older example from the 30’s.

Triplex branded Glass (after Jan 1969)

The year indication is still identical to the TOUGHENED or LAMINATED system, but the month code changed. The month of manufacture is now indicated by the dots over the word TRIPLEX:

image     image        image

August 75                                                                Later logo with unknown Date Code system

History of UK Glass Manufacturers for the Automotive Industry .

British Indestructo Glass Ltd (to be investigated)

Pilkington (now owned by Nippon Sheet Glass Co., Ltd).

In 1929 Pilkington and Triplex formed a joint company to build a works at Eccleston, St. Helens. Pilkington gradually increased its shareholding in Triplex until by 1965 it became the majority shareholder.

In Pilkington’s Queenborough factory on the Isle of Sheppey in Kent the original glass products were made under various brand names like Triplex, Sigla, Bilglas or SIV. Today they can still supply products with the original trademark. The Queenborough factory has made classic windscreens for the aftermarket since the late 1950s, and still retains the vast majority of the tooling produced ’’in-house’’. The range consists of over 2000 parts including, AC Ace, 1953/63, Mercedes 220 1961/71, Aston Martin DB 4 1958/65 and MG’s to name a few. The specialist factory is certified according to BS EN ISO 9001: 2000 ensuring that all legal requirements are met.

Triplex Safety Glass Co. Ltd. (Est. 1922).

Hythe Road, Willesden, London, N.W.10. “TripleX” laminated and toughened safety glass, both plate and sheet, Multi-ply and bullet-proof glass, Curved safety glass, Shaping, forming and manipulation of “Perspex” and other thermoplastic materials. Trade names: TripleX, Triplite, TriFlex.

image Tudor Safety Glass advertisement, 1956.

Tudor Safety Glass Co. Ltd. (Estd. 1935).

Spring Place, Kentish Town, London, N.W.5. Two toughening, ten bending furnaces: electricity, gas. Laminated and toughened safety glass, machinery glassware. Trade name: Vinylex. Tudor has been taken over by Triplex Safety Glass some decades ago and thus belongs to the Pilkington Group of companies.

One thought on “Triplex Glass Manufacturing Date Codes

  1. Paul

    I found the monthly date code system for the TRIPLEX glass actually changed in Jan 1968 and not Jan 1969 as posted. Many examples of the 1969 Monthly system are found on the 1968 Cars


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