The question of replacement glass arises in most sections on the forum from time to time. An outline of the suppliers used by Jaguar and the standards to look for may help in making an informed decision on whether to go for OE Jaguar or aftermarket if you are unfortunate enough to have breakage.

Many years ago I managed a Windscreen manufacturing plant in the UK for a period of five years. Output was split about evenly between OE (for Ford and a number of small British motor manufacturers) and aftermarket replacement. Details may have changed but the fundamental process is the same.

On our XK8's, windscreens are LAMINATED, side windows and rear screens are TOUGHENED. LAMINATED consists of an interlayer of PVB (PolyVinyl Butryl) sandwiched between two layers of float glass; TOUGHENED is a single sheet of thicker float glass. Both manufacturing processes involve heat and pressure. The main difference being TOUGHENED is rapidly chilled to create a surface tension which makes it more resistant to breakage than the original untreated FLOAT. LAMINATED is cooled slowly passing through a graduated furnace called a Lehr. When broken, LAMINATED glass cracks but is generally held together by the interlayer; TOUGHENED glass shatters into tiny pieces.

Why use different types? LAMINATED is better suited for curved screens installed in a surrounding frame or bonded into an aperture. It also meets very tough requirements to resist penetration in the event of impact. TOUGHENED (as well as being cheaper to produce) is the preferred solution for flat and opening windows. LAMINATED can be worked after the production process is ended (cut or polished). TOUGHENED must be fully worked before the toughening process. It will shatter if subsequently cut or polished. The polished edge on your door glass is done before toughening. Heated front windscreens have the very fine electric elements embedded in the interlayer. Heated rear screens have the heating elements screen printed on the inside surface before the toughening process.

FLOAT glass is the highest quality. It is produced by 'floating' a continuous ribbon of glass on a bed of molten tin. (we're talking major scale here - the ribbon is 5 Metres wide and half a Kilometre long). This produces an absolutely flat, fault free sheet. The older PLATE glass was produced between rollers. This created an uneven sheet which had to be polished but was never as flat as FLOAT.

The largest UK float glass manufacturer is Pilkington plc in St Helens. The largest UK automotive glass manufacturer is Triplex Safety Glass (a subsidiary of Pilkington). Triplex use FLOAT glass manufactured by Pilkington to manufacture windscreens. PVB Interlayer for the European market is manufactured by Monsanto and DuPont.

Jaguar has generally used glass supplied by Triplex Safety Glass although they have at times used other European manufacturers such as Sicursiv.

All motor vehicle glass, regardless of the manufacturer has to comply with national standards. For example BSI in the UK and ASI in the US. Many standards organisations recognise equivalence because the parameters and testing procedures are largely the same. Optical quality is a major consideration in the testing procedures. Bending glass inevitably introduces distortion. The acceptable limits of this are laid down in the standards. In order to be allowed to display standards markings on automobile glass, manufacturers are subject to regular inspection of processes and product.

The trade marks on your vehicle OE windscreen will be similar to this:



Screen Manufacturer & type = XXX Triplex Laminated
E11 = European Standards
AS1 = American Standards
001585 = green tinted
M1250 = black perimeter shading (?)
DOT682 = glass manufacturing plant
...5 = manufacturing year (this one is 2005)

The position of the dot around the XXX Triplex logo shows manufacturing month.

The side window marking is similar:



The main difference (other than showing it's Toughened) is the Year and Month of manufacture is the position of the two dots around the XXX Triplex trademark.

FLOAT glass, invented by Pilkington, is now manufactured all over the World. There are many other vehicle glass manufacturers apart from Triplex supplying OE and the replacement market.

Replacement glass suppliers will often offer a windscreen product other than Triplex. They can buy it more cheaply and the minimum order on units make it favourable for their bottom line. Is it as good? I'm not starting another 'best oil' kind of debate!

Graham

 

You don't have to. The installers have their own forum, and by their own accounts on their forum not all replacement glass is equal. They note that some are thinner, and some have optical imperfections such as waviness or other distortion. It can be very distracting for some drivers. If the glass is being replaced under insurance cover, then bear in mind that the insured is entitled to LKQ. Like kind and quality. Whether something is LKQ is always debatable.

For North American readers TOUGHENED==TEMPERED

Nice to get the inside scoop though.

(still no official thank you button here ... tried and failed)