WASHING I'OWHKRS FOR DAlin USE 187 



deposits will bake on harder. For hand wasliiiifj tliis tcinperaturo is too 

 severe and a lower temperature must be resorted to. However, up to al)out 

 1W° V. tlie liotter the better as re{!;ard.s the eleaning aetion. The baeterieidai 

 action is markedly reduced l)elow .35° C. or 95° F. 



From a survey of tlie powders used by a number of dairies in Massachu- 

 setts the outstandiufj; feature is that the majority of chanfres from powders 

 previously used has been for the adoption of powders containing tri-sodium 

 phosphate. The tri-sodiuni phosphate powders are held in high favor by 

 tliose using them and these powders are proving very desirable. There is a 

 tendency to avoid the use of strong caustic powders except for very sj)ecial 

 uses. 



A Suggested Composition for Washing Powders 



It may be safe to say that the best powder for dairy cleansing shouin 

 have no soap and no free caustic for hand washing, and little free caustic for 

 machine washing. A satisfactory powder should analyze apj)roximately as 

 follows: 



Sodium carbonate (anhydrous) 60% 



Tri-sodium phospliate (I2H2O) 40% 



Total alkali as NaOH about 58% 



Sodium hydroxide None (except 



what may occur free in the carbonate) 

 Soap None 



This combination has been found to give good results in all laboratory 

 tests as well as in all plant tests. It was found to be efficient in its cleans- 

 ing action and to jjossess all the desirable qualities of a good jiowder. Tliis 

 percentage coni])osition could be obtained from various mixtures of the com- 

 mercial chemical products which should be analyzed and mixed accordingly. 

 Conuiiercial tri-sodium j)hosphate ordinarily contains 12 molecules of water. 



For machine washing it may be deemed advisable to increase the total 

 alkali content by the addition of a little sodium hydroxide. 



Summary and Conclusions 



1. Analyses of many washing powders on the market show four general 

 classes, containing carbonate, caustic, phosphate and soap respectively. 



2. There is very slight variation in those powders which come in the same 

 class. 



0. Laboratory and plant tests on these powders, on other mixtures, and 

 on the pure ingredients have demonstrated the specific roles played by each 

 ingredient. 



4. A desirable composition for general dairy use has been indicated to be 

 60 per cent sodium carbonate and 40 per cent tri-sodium phosphate. 



5. By buying the commercial chemicals the price per jiound of cleaner 

 may be reduced to close to 2 cents as compared with from 8 to 16 cents now 

 paid for a similar grade of product. 



6. The wa.shing efficiency of the powders increased up to about 140° F. 

 Below 95° F. the bactericidal action is greatly reduced. 



7. All powders showed disinfecting powers in 0.6 per cent solution, l)y 

 rendering the wash water sterile. 



3 M-5-'28. No. 2366 



