TESTING CAR VARNISHES.
By D.D. ROBERTSON.
At the Master Car-Painters' Convention, D.D. Robertson, of the Michigan Central, read the following paper on the best method of testing varnishes to secure the most satisfactory results as to their durability, giving practical suggestions as to the time a car may safely remain in the service before being taken in for revarnishing:
The subject which the association has assigned to me for this convention has always been regarded as important. There is no branch of the business which gives the painter more anxiety than the varnishing department. It is more susceptible to an endless variety of difficulties, and therefore needs more close and careful attention, than all other branches put together, and even with all the research and practical experience which has been given to the subject we are yet far from coming to a definite conclusion as to the causes of many of the unfavorable results.
Beauty and durability are what we aim at in the paint shop, and from my experience in varnish work we may have beauty without durability, but we have rarely durability without beauty, so that the fewer defects of any kind in our work caused by inferior material, inferior workmanship, or any other cause, it is more likely to be durable, and ought, therefore, to possess beauty. There are certain qualifications absolutely necessary to durability in varnish. The material of which it is made must be of the proper kind, pure and unadulterated; the manipulation in manufacturing must be correct as to time, quantities, temperature, handling, etc., and age is also necessary. The want of durability arising from the quality of the materials, or from the manner of manufacturing, the painter has no control over; but let me say here, that frequently a first-class varnish has been used upon a car, and after being in service for a short time it deadens, checks, cracks, chips, or flakes, and therefore shows a very poor record. The varnish is condemned, when in reality, had the varnish been applied under different circumstances and over different work, the result would have been good and the durability satisfactory.
I am satisfied that in many cases first-class varnish has to bear the odium, when the root of the evil is to be found nearer the foundation. The leading varnish manufacturers of this country have expended large fortunes to secure the best skill and appliances, and, indeed, to do everything to bring their goods to perfection. Their standing and respectability put them beyond suspicion, and their reputation is of too much value for them knowingly to put into the hands of large consumers an inferior article; and even when we have just cause to complain of the varnish, we ought to be charitable enough to attribute the mistake to circumstances beyond their control (for every kettleful is subjected to such circumstances), and not to charge them with using cheap or inferior material for the sake of gain.
If the question which has been given me means to give some method of testing before using, I confess my inability to answer. For varnish to be pronounced "durable" must be composed of the materials to make it so, and to ascertain this, chemistry must be called in to test it. Comparatively few painters understand chemistry sufficiently to analyze, and if they did, and found the material all that is necessary, the manipulation may have been defective, so as to injure its wearing qualities, and therefore I cannot suggest any way of pronouncing varnish durable before using it.
As to the common custom of hanging out boards prepared and varnished to the exposure of the sun and weather for months does not seem to me to be the correct way of testing durability. It is true we may by this mode get some idea of wearing properties, but the most thorough and correct way is to put the varnish to the same exposure, the tear and wear, that it would have in the regular service on the road on which it is to run. Cars while running are exposed to circumstances which boards on the wall are not subjected to. The cars under my charge run through two different countries and three different States, and therefore subjected to such a variety of climate and soil that the testing by stationary boards would completely fail to give the correct result. For example: I have placed two sample boards, prepared and varnished, and exposed them to all kinds of weather and to the constant and steady rays of the sun for an equal length of time, and both gave favorable results; and I have also put the same varnishes on a car and found very different results. One of the varnishes having some properties adapted to resist the friction caused by cinders, sand, and dust, and consequently not so liable to cut the surface, and therefore much more durable.
The system which I adopted long ago, and to which I still adhere (not on account of "old fogyism," but for want of better), is as follows: I have two varnishes which I want to put into competition to test their relative merits. With varnish No. 1, I do the south half of the east end of the car and the east half of the south side of the car, the north half of the west end, and also the west end of the north side; this is also done with the same varnish. On the other half of the car varnish No. 2 is put.
Thus you will see it is so placed that, should the car be turned at any time, both varnishes on each side will have the same exposure and circumstances to contend with. This I regard as the best method to test the durability of varnish. And again let me say that it would be wrong for me to argue that because the varnish which I use gives me the best results, therefore I would regard it the best for all to use. This would be wrong, inasmuch as we have a diversity of climates between Maine and California, and between the extreme northern and southern States. The varnish which has failed to give me satisfaction may be most suitable for other parts of the Union.
As to the second part of my subject, "What length of time may a car safely remain in service before being taken in for revarnishing?" this must be regulated by the nature of the run and general treatment of the car while in service. Through cars are frequently continuously on the road, and little or no opportunity can be had to attend to them while in service. Such cars should be called in earlier than those which make shorter runs, and where ample time is allowed at both ends of the journey to be kept in order. And again, cars which are run nearest the engine cannot make so large a running record as those less exposed. Some roads, for a variety of reasons which might be given, can run cars for 14 months with less wear than others can run 12 months. So that I hold that the master painter on every road should keep a complete and correct record of his cars, and have an opportunity to examine these at intervals and report their condition, in order to have them called in before they are too far gone for revarnishing. If this system was more frequently adopted, the rolling stock of our roads would be more attractive, and the companies would be the gainers.
I cannot lay down a standard rule as to the exact time a car should remain in service before being called in for revarnishing, but I find as a general rule with the cars on the Michigan Central Railroad that they should not exceed 12 months' service, and new cars, or those painted from the foundation, should not be allowed to run over 10 months the first year. By thus allowing a shorter period the first year the car will look better and wear longer by this mode of treatment. Cars treated in this way can be kept running for six and seven years without repainting.