Off with the old: on with
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DEVELOPMENTS in vehicle-body refinishing materials over the past few years have been many. A considerable amount of work on paints has been done but probably the most significant change that has taken place in the industry has come with the introduction of what are termed low-bake systems. In the last Light Vehicles and Fleet Cars Supplement news was given of the installation of a lowbake plant by W. .J. Reynolds (Motors) Ltd., Dagenham, and now COMMERCIAL MOTOR has had a car put through the plant to assess the potential of the system.
The result was exceptionally good, but, before dealing with this, it would be as well to run through the developments in vehicle painting which have taken place in recent years to give a background to the exercise.
Low-bake ovens were introduced to this country just over three and a half years ago and there are now over 100 in use. This may not seem many in relation to the 13,000 refinishers in business but then the majority of these are small companies and what it does mean is that the larger refinishers are taking advantage of a system which can give considerable benefits. The main reason for the development of low-bake painting is to enable the refinisher to achieve the quality of factoryfinished vehicles. Durability, colour retention and weathering properties equal the original finish, a hard surface straight from the oven is given, there is excellent gloss-from-the-gun and, although normally no polishing is required, minor blemishes can be "polished out-.
Low-bake paints are of the alkyd/melamine type, which is the finish used by most British manufacturers. In factory-type stoving, oven temperatures go up to 300°F or higher and as a fully-trimmed vehicle could not stand this sort of temperature, special paint formulations have had to be developed to get the same result when oven baked at a comparatively low temperature-180°F to 200°F. A typical enamel is Dulux Low-Bake from ICI Ltd.. the major supplier of refinishing materials to the trade. This contains some cellulose to allow defects to be polished out.
Even though low-bake painting is gaining ground—another factor is the influence of car manufacturers who want the same quality as the original finish for paint-warranty work —the main refinishing paints used in the UK are based on cellulose, blended with synthetics giving fast air drying. A popular material of this type is Dulux Belco and these can be used over any type of paint used at present on vehicle production. They are polishable and easy to use but overnight drying is necessary and the main snag has been that cellulose-base paints can -yellow" badly in service, this showing up mainly in pale shades such as whites and blues. But there has been a lot of development in this connection and Belco, for example, has been reformulated to overcome yellowing. It is now recognized as a non-yellowing paint and can be used to touch-up factory finishes without further problem.
Vans used to be finished in cellulose but now an alkyd/melamine stoving finish is generally adopted and in the case of Bedford vans the finish can be acrylic.
This is a name which appeared in the UK in 1963 when Vauxhall were first finished in this material to bring them into line with the American General Motors practice. There has been a lot of talk of acrylics since then, and they are available for refinishing from manufacturers such as ICI and Berger. But these are not stoving paints and Vauxhall use a special process with a lacquer-type acrylic which is sanded off after application and any defects repaired and then stoved to get reflow. Ford now use a thermosetting acrylic which is stoved after application in the same way as alkyd/melamine enamels used by other manufacturers and it is likely that the use of acrylics on production lines will spread.
Not foolproof
While paints such as Dulux Belco and LowBake can be used over an original acrylic surface without problems, the same cannot be said for the use of air-drying acrylic finishing materials over other surfaces. Acrylic lacquer is not as foolproof as older types if the user lacks sufficient experience of it and/or does not follow instructions exactly.
No matter what type of refinishing material is used the preparation work required remains the same if a perfect result is to be obtained. This was amply illustrated in the demonstration of its plant by W. J. Reynolds (Motors) Ltd. The car used was one supplied by COMMERCIAL MOTOR and was selected to test the system thoroughly and yet not require excessive preparation work, such as panel beating and metal replacement. It was a 10 year-old Ford Zephyr with numerous small patches of rust but sound bodywork.
Installation of a low-bake plant does not provide a simple way of offering cheap resprays. This has been publicized in some quarters but a very low price can only be reached if the normal degree of preparation is not required or not given. This practice is not attempted by Reynolds, who insist on the highest standard of preparation and topquality materials—Dulux Low-Bake was used on the Ford—and who have gone to low-bake mainly on the grounds of improved quality and a much more efficient use of space available. Savings that accrue must be set against a cost of £14.000 for the plant—Reynolds' was manufactured and installed by Spray Finishing Systems Ltd.—and to recover even the capital charges and running costs a high volume of work is necessary.
Important factor
As far as the customer is concerned, reduced time off the road is an important factor and this is one way in which a firm such as Reynolds can make more efficient use of space. Instead of vehicles standing overnight waiting for the paint to harden they can be released immediately they have come out of the oven and any fittings replaced.
In the case of the Ford, the car was in and out of the Reynolds shop within one day. which in itself is quite remarkable compared with the traditional lengthy period required for a respray. But because a fair amount of preparation was necessary this was only achieved by a considerable amount of cooperation from the Reynolds operatives and the willingness of Ted Waite, manager of the bodywork and paint division, to have his workshop completely disrupted for the day. The car was in the workshop from 9 a.m. to 6 p.m. and during this time spent a total of 1 hr. 40 min in one of the two ovens of the plant. About half an hour was taken up in the spray booth applying four undercoats, and the same time was taken in spraying one singleand one double-header top coat. For the rest of the time at Reynolds the car was being worked on in the shop by most of the men available and during the 2 hr. or so that it took to remove fittings, rub down original paintwork and mask up, no fewer than seven men were working on the car at the same time.
The amount of effort put into the preparation was certainly justified when it was seen to have produced such an excellent job. The finish was as good as, if not better than, that achieved on factory production lines.
Worth considering
Under normal circumstances the job undertaken by Reynolds would have needed two days but even this is a very short space of time for a vehicle to be off the road for the amount of work carried out. Taking this into account and the quality of the finish, it is apparent that the introduction of low-bake painting makes the respraying of freet cars and vans a proposition worth a lot of consideration in many cases. Vehicles working in cities do not always cover a lot of mileage but they suffer body deterioration on a time basis, particularly if they never get the protection of a garage overnight. Although mechanically sound, below-standard paintwork can hasten replacement—not always possible in these times of financial stringency. Money spent on a respray can put off the day of replacement and some of it will, of course, be recoverable through a better second-hand value.
Reynolds quote approximate prices for Ford models—the company stress that they do not restrict their services to this make—and these are a useful guide to the expense that can be expected. Obviously the cost will depend on the condition of the vehicle but at figures ranging from £30 for an Anglia to £60 for a Zodiac Mk. IV a respray can be really worthwhile.