Some Notes on Car Paints

Very few motorists bother about the paintwork of their car except perhaps to choose the colour and complain if it fades after ten years of Sunday morning polishing, so it was with the idea of finding out exactly what went into the manufatture of paints that we visited the Paints Division of I.C.I. Ltd. at Slough.

We were met at Slough by Mr. Liddiard of the Publicity Department, who conducted us over the Slough plant which covers some 34 acres. The very modern office buildings are on one side of the road while the earlier factory premises are on the other. At Slough the bulk of the production is concerned with “Dulux” gloss finishes and “Du-lite’ emulsion paint, while the stoving finishes now predominantly used on car production are made at the Stowmarket factory, although the basic processes are very similar.

It was explained that paint is made up of varnish and several chemicals with imposing names like Urea Formaldehyde, in which is suspended various powders or pigments which give the colouring to the paint. The greatest advances in recent years have been made in the manufacture of the varnish, which by the use of chemically-treated resins can give a paint improved properties of durability, flow and gloss retention.

The first building to be visited therefore was the alkyd resin plant, which, with its complicated array of tubes and boilers, looks like something out of “Quatermass.” The boilers or “kettles” as they are called are heated by “Dowtherm” vapour, each kettle yielding from 750 to 2,000 gallons. The UF/PF resin section is where modern resins and varnishes are manufactured, the letters standing for the initials of the chemical a used. The kettles in this section are heated by oil. The varnish is then pumped via overhead pipes to a cooling canopy where the varnish is allowed to cool until it is at a safe temperature for thinning. It is then passed on to the blending department where it is filtered and mixed according to the needs of the production line. It was interesting to note that a few old varnish kettles fired by furnaces were still in use, the operatives stirring the varnish by hand and testing the consistency of the mixture by spitting into it. At least that was what we were told. Not surprisingly this varnish is as good as and sometimes better than the mass-produced varnish.

For the first time the pigments are brought into the process. These are taken from the dry colour stores in the appropriate quantities and passed to the ball mills. The ball mills are large circular drums lined with white porcelain bricks and half filled with steel balls. The varnish and pigment are then mixed together in appropriate quantities and poured into the ball mills, which are then set to rotate, usually for a number of hours. The porcelain bricks are used so that the metal will not contaminate the paint, and the steel or sometimes porcelain balls grind the pigment and varnish together. The paint is also mixed on roller mills with three rollers which knead the pigment and vehicle together. After “dispersion,” as the mixing process is called, the paint is pumped to large mixers holding from 100 to 1,500 gallons where the paint is gently swirled round by large paddles. The paint can be examined through doors in the top of the large mixers and the control laboratory make tests on all paints for colour, gloss, viscosity, drying time, etc. The mixture is then adjusted to bring it to the correct specification. With over 400 colours in the range this is a tricky job since probably half-a-dozen colours look the same to the layman. When the paint is finally to the technicians’ liking it is strained and put into the necessary containers. These are usually 50-gallon drums for despatching to motor manufacturers, but paint which is intended for the retail market is put into one-gallon tins (or less) on a rotary filling and capping machine. The correct quantity of paint is metered into each tin and the metal cap is fitted by another machine. Further along a label bearing the correct colour name is stuck on automatically. The tins are then conveyed on an overhead system to the warehouse where they are stored until ready for despatch.

There is also a small order department which executes small quantity orders for special colours, etc. It is theoretically possible to have a colour that no one else can obtain but because of small-scale production the cost would be very high.

There is also a large laboratory, research and technical service staff who are constantly checking existing paints, formulating new colours and processes and instructing users of I.C.I. paints in the best ways of applying them. A comparatively new department is the colour advisory department. This is staffed by expert stylists and colour consultants who will draw up schemes for whole buildings, such as schools, hospitals, factories, etc., and see that the colours harmonise. There is a special room where all types of colours and fabrics may be seen under different artificial lights so that colours will still harmonise under these conditions.

This then is just a brief glance at the manufacture of paint. Motor car paints are reaching a high standard of perfection and very few colours, even metallic and pastel shades, seem to fade after several years’ use. Jokes in the trade such as the “blackcurrant jelly” Vauxhalls which can still be seen on the roads and the metallic finishes on the early Phase I Standard Vanguards do not have any modern counterparts. Your car may be stove enamelled or sprayed but the finish will be as good as ever after several years’ hard use if a reasonable amount of care is taken. I.C.I. recommend frequent washing, occasional polishing and very infrequent waxing.

An interesting publication by I.C.I. is a little booklet called “Colour at the Show,” which is a survey of all the colours on the cars at the Motor Show. In 1958 there were 303 cars on the Stands. Of these only 11 were black! Although this is not representative of production figures it gives a good indication as to how public inclination is swinging. Breaking this down even further 131 cars had two-tone finishes, 26 metallic, 77 pastel shades and 58 “full” or darker colours, excluding black. Of the 58 full colours 27 were reds or maroon, 13 blue, 11 grey and 7 green, while of the 77 pastel shades 39 were ivories, fawn, cream, beige, etc., only 5 being yellow, 12 grey, 11 blue, 9 green and 1 coral. In the metallic finishes greys, greens and blues dominated.

I.C.I. are fully alive to the changing tastes of motorists and this little booklet helps them in their discussions with manufacturers who are always looking for new colours. Our visit to Slough showed us that there is a lot more to making paint than we had previously thought. — M.L.T.