tephen Gray samples le newest quick dryers
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TER a vehicle chassis has been delivered to a dealer, many le-consuming tasks have to be carried out on it before the erator can finally take delivery.
Once the body or tank has been fitted, one of the longest )s is probably painting the complete vehicle; with nventional methods this can take up to three or four days. e delays occur in the drying time necessary between each at of the paint.
If the vehicle is to be finished two colours, this accentuates problem, while sign writing ds to the difficulties. Obiusly, if these processes can speeded up and the vehicle inted completely in one day, th the operator and vehicle 3plier will benefit.
After some years of intensive iearch, ICI's paints division at mgh, Berks, has produced a int that is able to quicken the nting process. Known as lyurethane 383 it is used conjunction with a fast-dryprimer to completely paint a licle in one day.
After cleaning the bare metal iroughly using a body clean solution, the fast acting hing primer is applied. This he real bond between metal top coat which prevents ng and cracking.
Next, an undercoat or Id-up may be used to give
the final . paintwork a greater. depth of colour. Lastly, the polyurethane top coats are applied. If the paint is used conventionally, two coats are needed with a 20-minute delay between them.
However, the paint may be applied in other ways. Hot spraying, by heating the un-. thinned paint to a temperature which will allow it to "go off" quicker, requires only a single coat to complete the job.
Electrostatic airless spraying may also be used, but here more thinners are added to the paint mix and two coats are necessary with a thirty minute delay.
• The P383 line can even be brushed on, an application followed by old-time coach builders, but two coats are needed with an overnight air dry before the second is applied. For those coach painters who continue to want to use it, ICI still markets its original Coach Enamel finish. Application is similar to the polyurethane, with an etch primer base, but four hours are required before the ground coat is put on. This then needs overnight drying before application of the first of the top coats.
A full nine hours are then necessary before the last topcoat can be applied, and this too takes as long to harden. Like polyurethane, the Coach finish can be hot sprayed or brushed, and obviously hot spraying can dramatically speed up the drying process, as no thinners are added.