LETTERS TO OMNIBUS
Seeing Red
In Phil Ireland's article in Omnibus 149 he hinted at problems experienced with buses painted red. Perhaps I may be allowed to offer thoughts on paint.
If one examines tubes of paint (oils or acrylics) in an art shop, one will notice in any given price range that reds are generally rated at a lower permanence factor than other colours. To get high-permanence reds one has to go to higher price ranges. Obviously durable, light-fast red pigments are very much more expensive to produce. The same applies to the sort of paints that decorators use - the cheaper the paint the more one has to beware of fading reds.
When one comes to the top-of-the-range transport finishes, such as my favourite, Tekaloid, one can readily (and correctly) assume that at such a high price for this product, one will be safe with any colour, including red. This can be confirmed by experience on the Seaton Tramway. Here their trams operate in a seaside environment which is recognised as being very harsh on paintwork, yet the company's red trams, painted in Tekaloid, have shown little sign of deterioration even after ten years or so in that hostile environment.
I think that many people were dismayed, to say the least, when Messrs. Croda decided to discontinue production of Tekaloid (probably the usual case of Big Business accountants putting profits before quality). However, we can all breathe easily again, because the full range of Tekaloid colours is once more available, through Breakwell's Paints, of Leamore, Walsall.
Even with Tekaloid there are some colours, which are not very durable without further protection, and the firm does indeed specify which need a coat of varnish. I feel strongly that this should include any red paint. In any case, when one is considering a preserved vehicle which one hopes will keep its looks for many years, varnishing is always to be recommended, whatever its colour. Here I should like to pass on wisdom that I have received from others over the years.
Advice I once received from an Industrial Chemist with a Doctorate in the subject, and whose speciality was paint, is that gloss paint is essentially a compromise. It is (in simplified terms) a mixture of pigment and varnish. Pigment gives the coverage, and varnish gives the shine - the more pigment the less shine, and vice versa. Now there are many preservationists who like to finish off their vehicles with a mix of gloss paint and varnish ("it enriches the finish," so they say). This is a myth (and this is the advice I received from no less than the Technical Department of Thornley & Knight, the original Birmingham makers of Tekaloid paint). Because of this "compromise" factor, a mixture of top-coat and varnish has inevitably to be less glossy than unadulterated varnish, coats (preferably more than one) of which will achieve, not "better", but "best" finish.
One other thing - it is always best, when varnishing, to do so before the top-coat has completely "cured". This enables the varnish to "bond" with the paint beneath. We are talking here of varnishing within a week of top-coating. If one waits a long time after the final top-coat before varnishing it, this bonding will not take place, and the varnish will simply stick on top of the paint, giving rise to potential flaking and peeling at some time in the future.
Given present synthetic varnishes, it is also unwise to attempt to "freshen up" a tired-looking vehicle by giving it a rub down and re-varnish. The old interacts with the new, and in no time one may well find that the new varnish will begin to rival Nitromors in its paint-stripping properties (it has happened with a vengeance on the Seaton Tramway). Some may here ask how B.C.T. used to get away with their "Clean & Varnish" methods of years gone by. The answer is that they used old-fashioned copal varnish, not the new synthetics. Copal varnish cannot be obtained from the usual sources, but only two or three years ago I discovered that the Birmingham firm of George Hull (now of Ladywood) still included copal varnish in their catalogues.
However, one doesn't have to go in for re-varnishing. At the Black Country Museum we gave one vehicle a thirty-year test (Wolverhampton trolleybus 433). Through all those years the paintwork was preserved by an annual deep-clean followed by an application of polish ("Mer" I think was the brand used). It was only other factors that dictated a repaint a few years ago, but even now, with continuation of that treatment the bus still looks as if it left the paintshop only last week.
I apologise for the lengthy dissertation, but I hope it will help.
Stan Letts
Oldbury
Chapel Lane, Wythall, Worcs B47 6JX
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