14 MISC. PUBLICATION 604, U. S. DEPT. OF AGRICULTURE 
appearance, or the edible or shipping quality, or as causing any appreciable 
waste. The expression “free from serious damage” is associated generally with 
certain grade factors in U. S. No. 2 grades and finally, “free from very serious 
damage” with those in U.S. No. 3 grades. It is often necessary, however, to use 
two or more of the above expressions in one grade for certain factors. 
U. S. standards have been criticized for being too lengthy and too technical. 
It has been the policy of the Department to make standards as simple as possible 
but it must be remembered that the extent to which a standard reflects relative 
value of a product depends to a large extent on the completeness with which 
it defines various grade factors that influence quality. Therefore, whenever 
possible, grade factors are defined as definitely as possible in order to facilitate 
uniformity of interpretation. Descriptive standards, to be practical, must be 
reasonably specific. Some factors are very easily defined objectively by specity- 
ing the size of an area or the percentage of the surface of a specimen which 
may be affected. Other factors, such as color, firmness, and shape, are very 
intangible and can be defined subjectively only in general descriptive language. 
TOLERANCES IN U. S. STANDARDS 
Early in the development of U. S. standards as a basis for wholesale trading, 
it was found necessary to provide suitable tolerances in the various grades in 
order to allow for variations incident to proper grading and handling. Persons 
inexperienced in the application of standards often question the need for tol- 
Granmces. tho appiccs the necessity for them, however, such persons need 
only to visit a packing shed where any product is being graded and packed for 
shipment. 
In any commercial preparation for market operation it is necessary that sort- 
ing and packing be done rapidly in order to hold costs toa minimum. Certain 
types of products such as apples, peaches, citrus fruits, and onions, usually 
are passed over movable conveyor belts, and defective specimens are removed 
by sorters as they move along on the belts (fig. 2). Under such a system, it 
is not humanly possible for employees to see all defects in specimens, especially 
those which are not plainly visible, such as very small worm holes in apples 
or peaches. Consequently, a few defective specimens naturally go into the 
packed containers and unless reasonable tolerances are provided in the grades, 
products would rarely, if ever, meet grade requirements. 
The percentage of idlewences provided in grades for specimens failing to 
meet grade requirements varies with the different products, usually from 5 to 
10 percent. The latter tolerance is the most prevalent. However, serious 
defects resulting from freezing injury and soft rot which may develop further 
and spread to other specimens, are usually restricted to 1 or 2 percent. Where 
a total tolerance of 10 percent is allowed in certain grades, often this total is 
restricted to 5 percent for certain serious defects other than soft rot and freezing 
injury. 
STANDARDS FOR RAW PRODUCTS FOR PROCESSING 
In addition to developing U. S. standards for use in wholesale trading in 
fresh fruits and vegetables, the Department of Agriculture has formulated 
U. S. standards to serve as a basis for purchasing certain raw products for 
processing. The first set of such standards was issued in 1923 for cannery 
tomatoes. These standards were revised in 1926 and since that time their use 
has extended to practically all the principal States which produce tomatoes for 
