and durable
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• A0Ø %1•10 demonstrates a paintpaint manufacturer application process that cuts spray-booth turnround time and reviews practical aspects of durability in service
A DEMONSTRATION of vehicle painting was recently laid on for CM by Joseph Mason and Co Ltd, Nottingham Road, Derby, the main purpose being to show the reduction of spray-booth turnround time to a maximum of 8Ihr by the use of Masopar quick-drying polyurethane (QDP) one-pack paint. It also provided an opportunity to review the special paint problems of various types of operator arising from severe or unusual service conditions and the lack of foresight on the part of some firms in planning a painting job.
Anti-pollution propaganda has stimulated awareness generally that cleanliness and attractive appearance are a social amenity of aesthetic value. The significance of smart commercial vehicles as a measure of the operator's community standing as well as, in many instances, the virtues of the goods carried, has apparently increased.
Be that as it may, Mason's customers are becoming more fussy over appearance and they include hauliers in a variety of categories as well as psv operators. However, despite clean-air regulations and the anti-pollution drive, the amount of atmospheric pollution in many industrial areas still accelerates deterioration of paintwork, and the increasing use of road transport to convey chemicals or materials with a chemical content has highlighted the value of a chemical-resistant paintwork.
Moreover, the problem of combating the corrosive action of de-icing salt has become more acute owing to the time that many vehicles spend on motorways. Also, the abrasive action of grit-laden spray on vehicle panelling when travelling at sustained high speeds has exacerbated paint-preservation difficulties; and the excessively alkaline washing solutions often employed by unknowledgeable personnel have had a deleterious effect that is typically blamed on the paint manufacturer. The paint manufacturer, for his part, is hard put to it to cater for operators who run vehicles near the coast where the air frequently has a high salt content.
Tumround 'lolly'
A quick turnround in the spray booth is "lolly" in any operator's langnage so long as quality is not impaired by speed. In the observed test an old Bedford CA van had been cleaned and degreased in the normal way. A two-pack etch primer was applied (which would not have been necessary in the case of a new vehicle in works primer) and this occupied about 15m. Drying time was +hr.
In the next operation an undercoat was applied, the quick-drying time of which is the time-saving factor in any QDP painting job, the undercoat being a short-oil alkyl of a composition developed by the company. Application occupied +lir and drying time was 14-hr. Drying time of an undercoat of ordinary, synthetic paint may be as long as five hours.
Of special importance, the QDP enamel that is applied in the final operation has a "dust-free" time of 40/50min. Subsequently, it resists dust absorption during thedrying time of 4 /5hr. In the demonstration the vehicle was sprayed with QDP enamel in From start to finish, the operation occupied 3hr 15min and under normal conditions drying would have been completed in an additional 5hr. One painter was employed on the job; two men would have been needed to complete a comparable job on the bodywork of a big vehicle in the same time, including an artic with a 40ft semi-trailer. If the livery has more than one colour, application time is 'a multiple of the number of colours but transfers can be‘ applied to a panel as soon as the paint has dried. Chassis parts can be painted as a normal part of the operation and the paint gives a hard, easy-to-clean surface.
According to Joseph Mason, QDP has the advantage over other one-pack paints in that it has high-gloss retention and does not therefore tend to "go yellow", which is particularly important when pastel paints are used. While a two-pack polyurethane paint has a somewhat higher resistance to chemical attack, mixing of the base and reactant materials must be done under strictly controlled conditions to ensure that the ratio is correct.
QDP resists dilute mineral acid and alkali, detergent, salt water, beer, petrol, lactic acid, mineral oil, sulphur dioxide and wet cement. It is claimed to have double the resistance to these chemicals compared with a conventional alkyd enamel and to have a substantially better resistance than other polyurethane paints.
The enamel is also said to have a higher film hardness than other paints and to harden in service within four days compared with the normal average of seven days. It can be applied with conventional spray equipment by the hot-spray, cold-spray or the low-pressure hot-spray method.
A colour advisory service is offered by the company to enable the operator to plan a livery with a full knowledge of any variations in light fastness, opacity or other paint characteristic that could affect the cost of application and application time or its serviceability in particular operating conditions. Many operators are ignorant of paint properties and are unaware that the printing-ink colours on which they have • based a planned colour scheme cannot be matched by paint pigments.