Tempered glass is not the same as laminated glass. Tempered glazing is run through a furnace at high high and then quenched. Roller marks are a trademark of tempered glass which give it a wavy characteristic. This is caused from the rollers inside of the furnace. Laminated glass is typicall 2 pieces of float glass with a PVB (polyvinyl butyral) interlayer which is typically .030". The best way I describe the difference of the two types is as follows: Laminated glass is what is installed in the windshield of your car and Tempered glass is typically your door and back glass. Hope that helps.

You are correct in saying that Tempered Glass is normally used in Motor Car doors etc. It is also used where there is a chance of the glass being bumped, such as in a Patio Door. The reason is that when Tempered Glass is made, it is heated in an Autoclave and then quickly cooled. This forms different layers of compression and tension in the glass. This enables it to bend far more than normal glass before breaking. This gives it it's 'toughness' although it's actual hardness is not changed. It is because of these layers that tempered glass breaks in it's traditional way, which is into small crystals. In some countries this glass is legal in windscreens but have what is known as 'zone toughening' where the glass breaks into much larger pieces so as to enable the river to still see through it.They are mostly illegal because with the speeds of modern cars you are quite likely to end with your windscreen in your face and all over the inside of the car!

You are erroneous in saying that roller marks are a sign of Tempered glass. These marks come from the old 'Drawn Sheet 'way of glass manufacture where molten glass was drawn up between rollers to give it it's thickness. The only way to tell if it is tempered is to look for marks where the glass was gripped when being toughened. Another aspect of toughened glass is that once toughened it cannot be worked on or cut because as soon as the outer skin is broken it shatters!

Almost all glass is now made by the 'Float' method where glass is floated out on a bed of molten tin, hence 'Float Glass'. This method produces optically pure glass nearly as good as the older method of polishing 'Drawn Sheet Glass'. All safety Glass, tempered or laminated must carry a visible, sandblasted label stating what it is.

Tempered glass can be tinted in manufacture but it does not affect harmful Ultra-violet radiation.

Laminated glass on the other hand is made from two or more normal sheets of glass bonded together with a vinyl interlayer. This has the effect of preventing bending, unlike toughened glass. with Laminated glass the interlayer keeps the glass together even when smashed which makes it ideal for use as windscreens and any other application where safety is a problem but where it will not be subject to bangs such as in a patio door.

Laminated glass comes in different forms and thicknesses. A windscreen uses two sheets of glass with a standard interlayer or a high impact interlayer which is thicker and can take lot more punishment before being penetrated. The color you get in windscreens comes from the interlayer. High Impact and Multi Laminates are use when extra security is required, such as Banks Jewelry shops etc.

Flat Laminated glass with two sheets can be cut and processed, but multi laminate is made cut to size.

Another type of multi laminate is bullet resisting which come in different thicknesses depending on what you want to stop. Nineteen millimeter will stop a 9mm bullet but it takes up to fifty millimeters to stop a rifle bullet. These are characterised by having decreasing thicknesses of glass in them; 12mm on the outside going down to 3mm on the inside. Ordinary multi laminate has the same thickness glass throughout.

Another interesting type of Laminated glass is 'Sound Reducing Glass'. This has a very soft but thick interlayer. These are used in noisy applications such as airports.

One other very important aspect of laminated glass is heat and sun protection. There are many different types (a lot depends on what you want to use it for. I have even seen mini louvres laminated between two sheets of glass) The most common is a metal deposit placed on one sheet (the outside sheet) in a vacuum chamber. this varies in density depending on the requirement. The best is Gold!! These look like mirrors on the outside but have a remarkable effect on temperature. These are of course highly specialised. All laminated glass helps to eliminate harmful Ultra-violet radiation

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