6 CIRCULAR 5 9, U. S. DEPARTMENT OE AGHICTJLTUEB 



In many cases, dry-cleaning methods added more spray residue to 

 the fruit, than it originally bore. This was especially true for apples 

 having relatively small quantities of residue on them before cleaning 

 and when the equipment was not kept properly cleaned. 



It is probable that one of the effects of dry cleaning is more or less 

 to equalize the spray residue on different apples in a lot so that those 

 with large quantities on their surfaces become cleaner, while those 

 with lesser residue have more added. There is, however, only a small 

 proportion of residue that is entirely removed from all of the fruit, 

 even when the equipment is properly cared for. 



Repeated dry cleaning of apples with the same equipment has not 

 materially or consistently reduced the quantity of residue below that 

 obtained with one cleaning treatment. 



It was found, however, in the case of the cloth-roller type and the 

 revolving-brush type of cleaners, that two such machines set in tan- 

 clem arrangement were somewhat more efficient than one machine. 

 The first machine then accomplished most of the cleaning and this 

 made it necessary that the cleaning agents be changed more fre- 

 quently on this machine. 



Where an attempt has been made to increase the generally rather 

 limited capacity of dry wipers by hastening the progress of the fruit 

 through them, two undesirable conditions have generally resulted: 

 (1) The fruit has often been improperly cleaned, and (2) the possi- 

 bilities of injury to it have been increased. Each dry cleaner has an 

 estimated capacity. Before this is exceeded the operator should sat- 

 isfy himself that such action does not result in a lowering of cleaning 

 efficiency or in damage to the fruit. 



A very decided disadvantage of most dry-cleaning methods under 

 commercial conditions has been the practical impossibility of con- 

 stantly adjusting the equipment to the size of the fruit. Constant 

 attention is necessary to provide even reasonably suitable conditions 

 in this respect. In cases where the fruit sizes are extremely variable, 

 the sorting out of the extremes, previous to dry cleaning, may be 

 helpful in giving more uniform cleaning results with less damage to 

 the large-sized fruit. In addition, in some types of dry-cleaning 

 equipment, poor adjustment of the machine resulted in fruit being 

 thrown entirely out of the machine. Although the actual losses from 

 this cause were not important, the conditions under which they oc- 

 curred could not be considered suitable for the proper handling of 

 fruit. 



Practically all of the relatively satisfactory dry cleaners polish 

 the surface of the fruit and thus considerably improve its appearance. 

 However, they frequently do not polish the stem and calyx ends of 

 the fruit where often considerable quantities of dust and spray resi- f - 

 due are left after the fruit has been given a dry-cleaning treatment. V 

 The oscillating-brush dry cleaner is somewhat more efficient than the 

 others in cleaning the stem and calyx ends of apples. 



The relative efficiency of cloth wipers is determined largely by 

 the rate at which the fruit moves through the machine, by the clean- 

 ness and dryness of the cloths, and by the suitable adjustment of the 

 cleaning agents. 



Methods of cleaning cloths with solvents while they are in the 

 machine are not satisfactory. Changing of the cloths at least every 



