SELLING BY WEIGHT 



Federal Specifications contain information relative to two peri- 

 meters of the sponge and relative to the weight of the sponge, either 

 of which information could be used as a basis for the sale of sponges. 

 In the past, sales ordinarily have been made on the basis of weight. 

 Recently, many people in the industry have felt that sales should be 

 on some other basis. The members of the Soonge Exchange, for example, 

 recommend using perimeters (rather than "go-no go" holes) and the 

 writer recommends a simple three-diameter measurement. 



The need for the change is well known. In the past, up to 100 per- 

 cent weight has been added by foreign materials, which not only were 

 troublesome to put into the sponge but had to be removed from it before 

 it could be sold to the ultimate consumer. No one in the trade was mis- 

 lead by this practice. It was merely a nuisance. Today even with the 

 practice perhaps permanently discontinued, natural sponges still are 

 being offered in an unattractive form that favors the sale of compet- 

 itive materials in that varying amounts of gurry are left in to increase 

 the weight, which unfortunately results in unpleasant odor, unattrac- 

 tive appearance, and •undesirable feelo 



The seller caught in the change over to cleaner sponges is faced 

 with the problem of convincing the buyer that these cleaner — and there- 

 fore lighter — sponges should sell for more even though they weigh less. 

 Sales by volume or dimensions is the answer. The increased value then 

 is obvious, since the sponges are more pleasing in appearance when well 

 washed. Table 19 gives data illustrating the kind of analysis that 

 would enable the buyer further to recognize the enhanced value of the 

 well-cleaned sponge. The data in table 19 show that the first lot of 

 unwashed sponges contained, on the average, 36 to U8 percent of "gurry, " 

 on a dry basis. The second lot of sponges, which was representative 

 of the new voluntary standard, contained only 6.8 percent, on the aver- 

 age. These data indicate that a 10 percent content of material that 

 can be washed out is a reasonable maximum limit. 



Another factor that makes dimensions a better criterion than weight 

 as a basis for sales is the fact that a sponge that has been dried picks 

 up moisture rapidly from the air after it has been removed from the 

 drier. Experiments showed that Rock Island sponges soon picked up more 

 than i|0 percent of their weight when dried and then put beside a beaker 

 of water in a closed vessel. Under ordinary conditions, these parti- 

 cular sponges contained from 9*5 to 53 »5 percent moisture. The latter 

 figure was obtained on the specially washed samples and therefore in- 

 dicates that the hygroscopic property of the gurry is not the only 

 factor causing the sponges to absorb water from the air. Obviously, 

 sale by weight is inaccurate, since the content of moisture may marked- 

 ly vary from a dry to a damp day or as a result of the moisture that 

 has been purposely added. 



The method of determining diameters recommended by the writer 

 requires only an easily constructed measuring board. (This board was 

 described under water testing.) The sponge, which has been moistened 



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