Sealants and adhesives

SEALANTS AND ADHESIVES

Structural Adhesive

Metal-to-metal adhesive is applied to critical joint areas during factory assembly. The material used is a high-temperature, heat cured, nitrile phenolic which serves both to bond two metal surfaces and also to Where joints are inaccessible following the seal the joint against ingress of dust, water, petrol and reassembly or fitment of components, ensure that a fumes. This material is not suited for service use, and paste-type sealer is applied to such joints. Certain should be substituted in repair using a suitable seams also become inaccessible after the completion medium strength adhesive. of panel repairs. In such instances the paint process should be carried out and sealers applied before final When separating a joint treated with metal-to-metal assembly. adhesive, to avoid distortion it is recommended that the joint be gently heated until the bonds weakens Provided access is adequate, apply the sealer to both sufficiently to permit panel separation. sides of the repair joint. Where access is limited to one side only (e.g. box sections), inject the affected NOTE: Spot welding through box member with cavity wax. metal-to-metal adhesive is feasible, but take special care to adjust the transformer setting to ensure a reliable weld. DO NOT carry out MIG welding on a joint area which has been treated with metal-to-metal adhesive until all treated with wax and sealers. traces of adhesive have been removed. Sealing Water Leaks Seam Sealers Sealing charts in this section show those areas of the A heat cured, PVC Plastisol sealer is applied to joint bodyshell most likely to be affected by accident areas during factory assembly. This material is not damage and water leaks, and which could therefore suitable for service use. require re-treatment in repair. They do not show those joint areas which only apply to factory assembly Carry out seam sealing after the application of primer operations and which are unlikely to be disturbed in and before the surfacer and final paint coats. Ensure service (e.g. centre tunnel), or where the damage that surfaces are first cleaned of all grease and oil. would be so severe that the entire bodyshell would Apply the sealer material to the joint as a bead, either normally be written off. by hand or using an applicator gun. Brush sealer well into the joint and wipe smooth using a cloth soaked When water leakage occurs, always adopt a logical with solvent such as Shell SBP3. This will ensure an approach to the problem using a combination of skill, acceptable cosmetic finish. experience and intuition. Do not attempt to reach a Apply sealer to ALL accessible joints following repair conclusion based only on visual evidence, such as work. Be aware that damage to a vehicle can often assuming that a leak emanates from the windscreen result in deflection to those areas of the body which because the footwell is wet. It will often be found that are remote from the impact. The sealers in these the source of the leak is elsewhere. The correct areas can therefore be disturbed by subsequent procedure will increase the chance of locating a leak, straightening and repair operations. Check joints in however obscure it may seem. the vicinity of the area undergoing repair for evidence of cracked sealer, clean them out as required and re-treat them with fresh sealer using the following procedure:

• Clean the affected joint or seam and re-treat any exposed metal areas with a suitable etch phosphate primer.
• Treat affected area with an acid-etch primer.
• Apply appropriate seam sealer as necessary.
• Apply appropriate colour coat (and underbody sealer as applicable).

• CAUTION: ALWAYS deploy an extractor
• unit to remove toxic fumes when using
• oxy-acetylene equipment to remove panels