rust

Existing rust on the pinchweld

Always contact the dealership or the original equipment car manufacturer for the vehicle in question and see if specific instructions are available for rust repairs for pinchweld or flange. If specific instructions are provided by the *car manufacturer, they must be followed over any other aftermarket instructions.

Rust can be classified in the following 4 categories:

Light: Light rust noticeable on the surface orange in color.
Moderate: Some dark orange-red spots.
Severe: Pitting and reddish spots with raised uneven surfaces.
Critical: Small holes or loss of metal and perforation.

When a technician finds corrosion on the pinchweld it must be corrected and repaired. This is highly critical. Windshield bonding consists of several layers that are linked together like a chain from the metal in the pinchweld to the windshield. A chain is only as strong as its weakest link and a corroded pinchweld might be the link that bursts in a crash situation.

Also note that the corrosion might have spread in the metal under the paint layer and this could be difficult to detect.

Eftec Aftermarket recommends removing all corrosion mechanically in the pinchweld area. Eftec Aftermarket does not recommend treating corroded areas with chemicals like "rust converters" or "rust removers" as these often only provide a temporary relief for the corrosion problem. Eftec's 50 plus years experience in the corrosion prevention business tells us corrosion is almost impossible to stop with chemical treatment once it gets its teeth in the metal.

For severe corrosion (level 4) on the bonding area the metal panel must be replaced. For less serious corrosion (level 3) Eftec Aftermarket recommends removing all corrosion mechanically and have the surface professionally repainted without the clear coat if possible. If the clear coat remains it can be removed with medium fine sandpaper.

For moderate corrosion (levels 1 and 2) after removing the corrosion mechanically and if only small areas of bare metal are exposed, i.e. no more than 15% of the bonding surface, it is recommended to use either D-528 or D-530 to cover the metal area and bonding surface (carefully avoid priming the freshly cut urethane if any remains). D-528 and D-530 have shown very good results for rust protection in laboratory salt spray chamber tests, especially when applied in two layers with 20 minutes of drying time in between, and perform at least as well as so called etch primers.

D-528 and D-530 are also low conductive and thereby also provide a barrier against electric currents which could cause corrosion or other problems.

Scratches on the Pinchweld

Scratches often occur when cutting out a windshield as tools cut through the old urethane. These scratches also should be covered with either of two black primers DINITROL D-528 or D-530.

These primers offer an excellent base for the replacement bonding of windshields, as DINITROL urethane can be applied on top of the primer. Covering the bare metal spots with DINITROL D-528 and D-530 also provides the needed corrosion prevention.

* General Motors does have instructions specific for rust and pinchweld flange repairs. Contact GM at:

General Motors Corporation
100 Renaissance Center
P.O. Box 431301
Detroit, MI 48243-7301


	Rust and Rust Prevention on the Pinchweld Existing rust on the pinchweld Always contact the dealership or the original equipment car manufacturer for the vehicle in question and see if specific instructions are available for rust repairs for pinchweld or flange. If specific instructions are provided by the car manufacturer, they must be followed over any other aftermarket instructions. Rust can be classified in the following 4 categories: Light: Light rust noticeable on the surface orange in color. Moderate: Some dark orange-red spots. Severe: Pitting and reddish spots with raised uneven surfaces. Critical: Small holes or loss of metal and perforation. When a technician finds corrosion on the pinchweld it must be corrected and repaired. This is highly critical. Windshield bonding consists of several layers that are linked together like a chain from the metal in the pinchweld to the windshield. A chain is only as strong as its weakest link and a corroded pinchweld might be the link that bursts in a crash situation. Also note that the corrosion might have spread in the metal under the paint layer and this could be difficult to detect. Eftec Aftermarket recommends removing all corrosion mechanically in the pinchweld area. Eftec Aftermarket does not recommend treating corroded areas with chemicals like "rust converters" or "rust removers" as these often only provide a temporary relief for the corrosion problem. Eftec's 50 plus years experience in the corrosion prevention business tells us corrosion is almost impossible to stop with chemical treatment once it gets its teeth in the metal. For severe corrosion (level 4) on the bonding area the metal panel must be replaced. For less serious corrosion (level 3) Eftec Aftermarket recommends removing all corrosion mechanically and have the surface professionally repainted without the clear coat if possible. If the clear coat remains it can be removed with medium fine sandpaper. For moderate corrosion (levels 1 and 2) after removing the corrosion mechanically and if only small areas of bare metal are exposed, i.e. no more than 15% of the bonding surface, it is recommended to use either D-528 or D-530 to cover the metal area and bonding surface (carefully avoid priming the freshly cut urethane if any remains). D-528 and D-530 have shown very good results for rust protection in laboratory salt spray chamber tests, especially when applied in two layers with 20 minutes of drying time in between, and perform at least as well as so called etch primers. D-528 and D-530 are also low conductive and thereby also provide a barrier against electric currents which could cause corrosion or other problems. Scratches on the Pinchweld Scratches often occur when cutting out a windshield as tools cut through the old urethane. These scratches also should be covered with either of two black primers DINITROL D-528 or D-530. These primers offer an excellent base for the replacement bonding of windshields, as DINITROL urethane can be applied on top of the primer. Covering the bare metal spots with DINITROL D-528 and D-530 also provides the needed corrosion prevention. General Motors does have instructions specific for rust and pinchweld flange repairs. Contact GM at: General Motors Corporation 100 Renaissance Center P.O. Box 431301 Detroit, MI 48243-7301