Caustic Soda the Best Cleaning Agent for Milking Rubber

New Zealand Journal of Agriculture, Volume 81, Issue 4, 16 October 1950, Page 300

Caustic Soda the Best Cleaning Agent for Milking Rubber

THE need for conserving milk- -®- ing-machine rubberware is perhaps not as great now as during the war, when the raw material was practically unprocurable and rubberware of any kind was very scarce. Rubber through which milk flows or with which it comes in contact must still be kept clean, however; as maintenance of cleanliness is essential to rubber conservation, these two desirable objectives are complementary. Results of trials to determine the effects on milking rubberware of four different methods of cleaning are detailed in this article by J. M. Kristensen, Special Inspector, Department of Agriculture, New Plymouth.

RUBBER of high quality is the best arid cheapest to use. The enemy of rubber is oil, grease, or any other fatty substance, so it is imperative that the outsides of machine rubbers be washed thoroughly immediately after milking has been completed. Many farmers discard inflations very frequently with the aim of maintaining uniform milking; this procedure could be modified, and if inflations were properly looked after, their life would be longer. Rubberware can best be conserved by the regular use of a detergent and a method of cleaning which effectively removes fat, and unless such a method is used fat quickly penetrates into the pores of the rubber and destroys the inside surface. The most satisfactory cleaner for the purpose is caustic soda, and the methods recommended were described fully in an article by W. G. Batt in “The Journal of Agriculture” for November, 1949. The use of caustic soda rather than other cleaners has been the subject of a great deal of controversy among farmers, some arguing that caustic soda tends to cause milkstone to collect more readily on metal parts as well as on the inside of rubberware of milking machines. That is not so, as it has been found that use of washing soda and cleaners other than caustic soda often causes greater accumulation of milkstone and results in poorer cleaning of rubberware than if caustic soda had been used. Inflations, which are constantly flexed while the machines are in use, must be kept at a uniform tension for efficient milking, so fat impregnation must be prevented as far as possible. Fat penetrates most readily at the point of contact with the teat, and the bulging at this point is caused by the rubber becoming fat saturated. That is proved by the fact that when such fat is extracted the inflation returns to its normal size and shape, as is shown by the results given in the lower table on the next page.

Four Methods Tried Results of trials carried out to ascertain the effect on the rubberware of different cleaning methods are very illuminating. Complete sets of new, grey, soft inflations were fitted to a milking machine which has 4 sets of teat-cups, and to identify the inflations they were marked in large letters with ink pencil before being fitted into the cups. Those for the first set of cups were lettered IA, 18, IC, and ID, for the second 2A, 28, and so on. Each set of cups was cleaned in a different way and with a different solution. Group 1 was cleaned as recommended by the Dairy Division; that is, by a liberal flushing through the cups of cold water, followed by at least 1 gallon of boiling water containing caustic soda at the rate of 1 heaped teaspoonful per 4 gallons, and finally another gallon of boiling water. This treatment was carried out twice daily after milking. Group 2 was treated similarly to Group 1 in the morning, but in the evening the caustic soda was omitted, the flushing being done only with cold water followed by boiling water. Group 3 was cleaned in the morning with caustic soda similarly to Groups 1 and 2, but in the evenings the solution which followed flushing with cold water consisted of 1 gallon of boiling water in which was dissolved about i handful of washing soda. - The final flushing was with another gallon of boiling water. Group 4 was cleaned both morning and evening with a washing soda solution as ■ used in the evenings for Group 3, the routine being cold-water rinse, then washing soda and boiling water, and finally boiling-water rinse. These cleaning methods were applied to the machine for nearly 4 monthsfrom August 2 until November —during which time the herd

consisted of 35 cows. The inflations were then removed from the teatcups, dried, and weighed carefully. They were measured for length and for circumference of the bulged portions which had developed where the inflations squeezed the cow’s teats. The inflations were then kept as hot as possible (about 200 degrees F.) for 3g hours in a strong solution of caustic soda teaspoons in 2 quarts of wateraccording to the method recommended by G. M. Moir in the “Journal” for September, 1943. This method of extracting fat from the inflations is several thousand times as intense as the usual daily cleaning procedure, because the caustic solution is very much stronger and is applied for hours instead of for about a minute. After removal from this, strong solution - the inflations were rinsed thoroughly with very hot water to wash off the butterfat soap which was produced. They were then allowed to dry before the final weighing and measuring. Results of Trials The results given in the upper table on page 301 show that less fat was extracted from the Group 1 inflations than from any of the others, the average from Group 2 was a little higher than from Group 3, and Group 4 yielded most of all; in fact, the use of washing soda twice daily instead of caustic soda allowed the inflations to absorb twice as much fat. Washing soda is nearly two-thirds water, and even when a liberal amount is used it does not provide a strong enough cleaner. The results show that cleaning with caustic soda twice daily, as applied to Group 1, was much the most efficient way to check the absorption of fat left on the surface of the rubber after . - milking. -

CLEANING MILKING-MACHINE RUBBERWARE

Group 1 in the table below show the superiority of caustic soda cleaning over other methods for conserving rubberware and giving better and quicker milking. The results prove that absorption of fat is the cause of inflations increasing in length and circumference so that they become slack and milk less quickly and efficiently. Caustic Soda Method Proved Best More than 30 years of experience has shown that the best way to keep the inflations and other parts of a milking machine in good hygienic condition is to apply twice daily the caustic soda-boiling water method recommended by the Dairy Division. The conclusion to be drawn from the trial described is that this, method also ensures that the inflations are maintained in the best possible condition to give long and efficient use. The inflations used were all new and the trial was carried out on the property of an efficient and reliable farmer who agreed to bear with the inconvenience caused by the use of four different cleaning methods.

Many different kinds of detergents have been manufactured and marketed, but experience under all conditions has shown that caustic soda used properly is the best cleaner, because its regular use with boiling water removes nearly all trace of fat. Three good reasons why milkingmachine rubberware should be conserved are that a perished surface in rubber harbours bacteria and provides intense contamination; that such a condition may assist the spread of mastitis; and that inflation rubbers give quicker milking if they retain their tension.

IN PRODUCTION AND DISTRIBUTION OT 41 K

Weight In Before grammes After Reduction by fat Group Weight In gra Before treatment tn mmes After treatment extraction Reduction by fat it extraction IA 41.03 39.30 1.73 IB 41.05 39.50 1.55 IC ' 41.45 39.70 1.75 ID 42.20 40.80 1.40 — - — Average 1.61 2A 41.70 39.00 2.70 2B 41.65 39.01 2.64 26 42.50 40.05 2.45 2D 41.50 39.03 2.47 Average 2.57 3A 41.35 39.04 2.31 3B 41.47 39.00 2.47 36 41.35 39.02 2.33 3D 41.00 39.00 2.00 Average 2.28 1 4A 42.20 39.03 3.17 4B 42.09 39.07 3.02 46 42.12 39.06 3.06 4D 42.18 39.04 3.14 ■ » 1— !IHI Average 3.10 The strong caustic treatment, as well as extracting fat, also also reduced the reduced the sizes of the inflations. Results for

Circumference at point of bulging Length of Inflation (inches) (Inches) After 'Group treatment Length of Inflation (inches) Circumference at point of bulging Before treatment Reduction (inches) Before After ■Group treatment treatment After treatment Reduction Before Before treatment Reduction treatment After treatment Reduction IA 6 12/16 12/16 6 11/16 6 1/16 11/16 3 14/16 1/16 3 12/16 3 2/16 14/16 3 12/16 2/16 IB 6 12/16 12/16 6 11/16 6 1/16 11/16 3 14/16 1/16 3 12/16 3 2/16 14/16 3 12/16 2/16 IC 6 13/16 13/16 6 12/16 6 1/16 12/16 3 14/16 1/16 3 11/16 3 3/16 14/16 3 11/16 3/16 ID 6 12/16 12/16 6 10/16 6 2/16 10/16 3 15/16 2/16 3 12/16 3 3/16 15/16 3 12/16 3/16 2A 6 13/16 13/16 6 11/16 6 2/16 11/16 4 3/16 2/16 3 14/16 4 5/16 3/16 3 14/16 5/16 2B 6 12/16 12/16 6 10/16 6 2/16 10/16 4 4/16 2/16 3 14/16 4 6/16 4/16 3 14/16 6/16 20 6 12/16 12/16 6 10/16 6 2/16 10/16 4 3/16 2/16 3 15/16 4 4/16 3/16 3 15/16 4/16 2D 6 13/16 13/16 6 11/16 6 2/16 11/16 4 4/16 2/16 3 15/16 4 5/16 4/16 3 15/16 5/16 3A 6 14/16 14/16 6 12/16 6 2/16 12/16 4 1/16 2/16 3 13/16 4 4/16 1/16 3 13/16 4/16 3B 6 14/16 14/16 6 11/16 6 3/16 11/16 4 3/16 3 13/16 4 3/16 3 13/16 3/16 30 6 13/16 13/16 6 11/16 6 2/16 11/16 4 1/16 2/16 3 14/16 4 3/16 1/16 3 14/16 3/16 3D 6 14/16 14/16 6 12/16 6 2/16 12/16 4 1/16 2/16 3 13/16 4 4/16 1/16 • 3 13/16 4/16 4A 7 1/16 1/16 6 14/16 6 3/16 14/16 4 3/16 3/16 3 15/16 4 4/16 3/16 3 15/16 4/16 4B 6 14/16 14/16 6 11/16 6 3/16 11/16 4 2/16 3/16 3 15/16 4 3/16 2/16 3 15/16 3/16 40 6 15/16 15/16 6 11/16 6 4/16 11/16 4 3/16 4/16 3 15/16 s 4 4/16 3/16 3 15/16 / 4/16 4D 7 6 12/16 12/16 4/16 4/16 4 4/16 4 4 4/16 4/16 4 4/16