The New Zealand Railways Magazine, Volume 2, Issue 7 (November 1, 1927)
Tarpaulins. — Their Manufacture and Care
A Tarpaulin may seem, to most people, a small thing in the equipment of railways, but it is a very important and indispensable article.
Great care must be exercised in the manufacture of tarpaulins, first by securing a suitable canvas and dressing, and then by good workmanship.
Canvas for tarpaulins must be of first class quality, carefully woven with a good yarn (preferably of long flax, free from admixture of any other fibre) and should count not less than 26 double threads in the warp, and 26 single threads in the weft, to the inch. Strips of canvas lin. wide by 20in. long, between the points of tensile, must, when tested, bear a strain of 300lbs. in the direction of the warp, and 350lbs. in the direction of the weft.
After a suitable canvas has been secured, the next question is a suitable dressing. After considerable experiment it has been found that a black dressing is most suitable. A black dressing is now being manufactured by the Department and is at present in use. It has been found to stand up to service conditions very well, making a good, light, flexible and durable tarpaulin.
Now we have a good canvas and dressing, the next important operation is the manufacture of tarpaulins.
The canvas is passed through a dressing machine which dresses it on both sides and squeezes out the surplus dressing. The canvas is then hung up to dry, and, when dry, is taken to the sewing machinists.
Special sewing machines are used for the manufacture of tarpaulins, and are equipped with double needles so that when sewing the cloths of canvas together they sew two rows of stitching in the one operation.
Care must be taken to see that the machines are in good working order, and adjusted so as to give the best possible results, and the operator must be qualified to run his machine so that a thoroughly good job may be turned out.
After the sewing machines have completed their operation the tarpaulin goes to the grommeting machinist who sews in the rings; he then hands it over to the sailmakers, who splice in the ropes. The tarpaulin is then ready for the dressing board to which it now goes.
The tarpaulin is stretched on the dressing board and is dressed by hand in order to make a good watertight job, special attention being given to the seams. The tarpaulin is then hung up to dry, branded, and, when thoroughly seasoned, issued to the traffic for use.
It will be seen that the manufacture of tarpaulins is an important work; the cost is considerable, and great care must be taken to make a good reliable, and waterproof job of them. Without this attention goods are liable to be damaged, entailing compensation.
Now this brings me to the point of this article, namely the amount of damage done to tarpaulins when in use.
Doubtless this damage could be very much reduced if not entirely avoided by increased care. Being a heavy item of expenditure it is in everybody's interest that greater care should be taken of them in order to reduce the expenditure on repairs.
A few Don't for Tarpaulins:—
Don't drag a tarpaulin off a load by main strength, and so tear it on the sharp corners of cases, etc.-ease it up.
Don't use tarpaulins for dropping cases on, to save the cases,—have a sack filled with straw handy.
Don't put a tarpaulin on the floor of a wagon and load heavy goods on top of it.
Don't sheet a partly full wagon so that the sheet will form a pond for water. Load and sheet wagon so that the water will drain out at the bottom of the door.
Don't roll up tarpaulins when they are wet, or they will soon go mouldy and rot if left for any length of time.
Don't forget that tarpaulins, together with all other railway equipment are your own property, so protect your own property.