Carstrip Pty Ltd is a specialist company that was established approximately six years ago to strip paint from cars, by utilising a plastic media dry stripping system. The service has since expanded to include stripping of trucks, buses and aluminium hulled boats. The stripping system is versatile enough to handle fibreglass, aluminium and other exotic materials.
Competing stripping processes involve the use of paint stripping solvents, acid dipping, hand stripping and sand blasting.
The use of paint stripping solvents is the most conventional method of stripping car bodies for respraying. Chemical strippers are applied to the car body by brushing and allowing to soak for a period of time, after which they are removed by scraping and water washing. Typically about 10 litres of stripper would be used on a car. This method has the disadvantage of generating large amounts of waste which require specialist disposal, and can adversely affect respray quality due to migration of the stripper into seams on the car body. In addition, solvents cannot be used on fibreglass materials. Stripping in acid baths has similar problems with sludge generation and migration of acid into the car body.
Hand stripping is an extremely time consuming process, and generates reasonably large quantities of dust. Sand blasting is not a process that is usually recommended for paint stripping, as it can damage the metal surface and may require excessive filling upon respraying.
Cleaner Production Initiative
The stripping process utilised by Carstrip was developed in the USA by Pauli & Griffin. The system was initially developed for paint stripping in the aeronautical sector and utilises a finely ground plastic to remove the paint coating via a mild abrasive action.
Paint stripping using plastic media
Paint stripping is carried out using a machine specifically designed for use of plastic media. The operation is undertaken in an enclosed, 15 metre long booth which allows collection and reuse of the plastic grit. Fines, dust and other rubbish are removed by an internal screening process. Small losses of plastic grit occur due to attrition. The booth can accommodate tour buses and large trucks.
The plastic media used in the stripping process is a thermoplastic acrylic resin. This resin was initially imported from the USA, but is now manufactured by Carstrip from virgin scrap material (offcuts, etc) supplied from moulders. The irregular granular shape of the plastic particles provides a sharp cutting edge which gives excellent cutting and lifting properties, without the hardness to damage the surface underneath.
Advantages of the Process
The process was originally developed in the USA as an alternative to chemical paint stripping of air force and commercial aircraft. It offered a number of advantages, including elimination of sludge generation, reduced labour and a safer and cleaner working environment.
The process is a dry process and dust control is relatively straight forward. Paint dust residue is suitable for non-specialist disposal within the normal industrial waste stream.
The advantages of the process over other methods are that it:
- avoids the use of caustic chemicals and organic strippers;
- reduces the quantity of waste generated;
- does not generate any gaseous or liquid wastes;
- is potentially applicable to a wide range of substrates through process modification (eg. variation of air pressures);
- reduces heat generation and transfer, which eliminates the risk of panel warping - a risk with other blasting methods;
- uses plastic grit manufactured from plastic scrap, which can be reused; and
- is quicker than most other methods.