PRESERVATION OF FTSH NETS. 7 



But it is not necessary to ^o further into this disputed subject. It 

 stands to reason that fish perceive differences of brifjhtness, and 

 probably of color, and that if we make a net similar to sea water in 

 both shade and color it will not be so readily visible. Those who 

 mi<rht wish to jro into this subject are referred to the article by 

 Reeves (1919). 



PRESERVATION OF NETS BY TANNING MATERIALS. 



The materials most widely used for curing nets are tanning ma- 

 terials — barks of birch, oak, spruce, hemlock; extracts of bark or 

 wood, such as catechu, quercitron, quebracho, and the like. For pre- 

 serving, the original process consisted of immersing or soaking the 

 net in a decoction of bark, or in a solution of the extract. One of the 

 earliest methods was the so-called " cold-tanning," a slow process 

 described by Aase (1912) . This writer says that the old Xorse fisher- 

 men used the same nets over and over for from 30 to 50 years. He 

 also sa3^s that while much of this superiority of their nets might be 

 explained by the fact that their thread was selected and spun by hand, 

 and therefore better than modern machine-spun threads, the differ- 

 ence between those times and the present, wdien one is lucky to use a 

 net for from 3 to 10 years, is too great to be explained by the home- 

 spun theory. He accounts for the difference by the cold-tanning 

 process, described as follows : 



COLD TANNING. 



Every net owner had his own Uirge tanning vessel, which provided a place 

 for botii bark and net. In this vat was placed as much water as there was use 

 for, and to every barrel of water was added li vog (1 vog=36 pounds) of birch 

 bark, well broken up. This was allowed to stand four or five weeks, but was 

 daily stirre<l around with a stick so that it cou-d not become thick and slimy. 

 The nets were put into this mixture. In the bottom of the vat a hole was pro- 

 videtl so that the finished liquor could be tapped into a tub and poured back over 

 the net to cover thoroughly the upper part of the net which otherwise nught 

 not come under the bark. The net remained in this vat two or three days, and 

 every day the liquor was poured over it several times. 



Such a barking gives little color, l)ut makes the net hard. To produce the 

 desired color it must not go into the bark a single time only. Nay, it nnist be 

 dried and again laid in the tan vessel if there is any bark left, as many as 

 four or five times. After it is dried it is dipped into the sea, and it now takes 

 on its right color for the first time — a color it will hold for years. If the barking 

 is repeated every year the net be<'onies harder and Iiarder as it grows older. 



The method takes a long time, and demands much labor ; when more and 

 greater nets began to be used, and prices of birch bark also rose, other methods 

 of barking began to be tried. 



HOT TANNING. 



The next step in the development of processes of net curing was 

 the employment of a warm barking. The bark is boiled, and the 

 nets are treated in the hot decoction. Aase is authority for the state- 

 ment that " with this method of tanning the net accjuires color and 

 hardness with one treatment, and much time can by this method be 

 saved. T')ut experiences has shown that warm tanning does not endure, 

 by a great deal, so long as cold tanning." 



