524 U. S. BUREAU OF FISHERIES 



sometimes, a 12-peiiny nail. The sound conveys to the ear of the 

 tester an unmistakable meaning as to the condition of the can, and 

 the faiilty cans that escape notice during the other tests are almost 

 invariablj^ found in this one. 



LACQUERING 



A common custom in the salmon-canning industry, but one that 

 is not common in the canning of vegetables, fruits, etc., is that 

 of lacquering the cans. This idea of protecting the can on the 

 outside has been followed from tlie very beginning for two reasons: 

 (1) That the English market which, at that time especially, absorbed 

 the greater part of these goods uisisted on their shipments being 

 finished in tliis way, and (2) from the fact, as these canners speedily 

 found out, that if they did not protect their cans in some way enor- 

 mous losses through rust would ensue. 



The first experiment of this nature was to paint the cans by hand 

 with red paint, treating each singly. Next a composition of logwood 

 extract and alcohol was tried, which, however, did not produce satis- 

 factory results for a very plain reason— the can was dyed instead of 

 bemg lacquered. The next attenq)t was to varnish the cans with a 

 japan variiish reduced with alcohol, but this was found to dry too 

 slowly for speedy handhng. After extended experimentation the 

 quick-drying brown lacquer of the present time was evolved, which 

 carries asphaltum in the form of an asphalt varnish as its base, this 

 being supplanted in some cases by gilsonite, Tliis lacquer can be pro- 

 cured in either a heavy or light body, is generally reduced with ben- 

 zene or gasoline, and is applied according to the requirements of the 

 market, which in some localities demands a heavy coating and in 

 others a much lighter finish, the latter giving a rich golden brown 

 color. Some experiments have also been made in using brighter col- 

 ored lacquers for this work. Several of these, made to give a bright 

 golden, copper, or other color, are extremely attractive in appearance, 

 while at the same time protecting the tin against rust quite as well 

 as the brown. 



The industry soon outgrew the hand method of lacquering, and the 

 process which for a number of j^ears was universal in the trade and 

 is still used by some canneries succeeded it. For tliis there are a 

 number of rectangular box vats about 40 by 80 inches and 18 inches in 

 depth, the number varying with the capacity of the cannery. These 

 are usually lined with galvanized metal and provided with a grid- 

 iron-shaped iron frame, hung from a windlass or other tackle for 

 lifting or lowering from top to bottom of the vat. The cans are 

 loaded on this gridiron, being placed in an inclined position to allow 

 the draining of the lacquer, and are lowered in the vat sufficiently to 

 submerge them in the lacquer with which the vat is charged to a 

 depth of 7 to 10 mches. The loaded gridiron is then raised to the 

 top of the vat and the cans allowed to drain and dry before pihng. 

 This method, while being more effective in regard to the volume of 

 work, was still of necessity a very slow and tedious operation. In 

 damp or rainy weather, especially when it is not possible to open 

 warehouse doors and windows, the gas arising from a number of 

 these vats makes effective drying almost impossible. 



Another principal objection to this method of lacquering^ which 

 apphed also to all earUer attempts, was the impossibihty of obtaining 



