LIQUID FISH GLUE

Cold liquid glue can be made from the heads, skins, and skeletal wastes of cod, haddock, mackerel, hake, and pollack. A great advantage of liquid fish glue is that it remains in liquid form and consequently has an almost permanent working life. An advantage of using it to make wood joints is that it sets slowly and therefore penetrates further than other glues before hardening.

Since liquid fish glues are not very water-resistant, a casein or other glue should be used where water-resistance is needed. Thick fish glues produce stronger joints than thin solutions.

Tools and Materials

• Fish heads, skins, and skeletal waste
• Large pan for washing fish parts
• Steam bath or double boiler
• Paddle for stirring
• Filter, such as cheese cloth

To make the glue:

• Wash the fish material thoroughly to remove blood, dirt and salt. If salted fish are used, wash them in running water for 12 hours.
• Once the material is washed and drained, put it into a large container, cover it with water, and cook it slowly at a low temperature, about 60 [degrees] C 140 [degrees] F). Cooking in an open pot helps to eliminate unpleasant odors in the glue. A steam bath or double boiler should be set up so that live steam surrounds the pot. Stir the contents occasionally. The length of the cooking period varies with the kind of fish material used.
• Let the cooked mixture settle. Skim off and discard the grease. Pour the remaining contents of the pot onto a filter.
• Concentrate the filtered fluid by slow heating to the desired thickness. This is the glue; it can be stored in convenient containers.
• Take the fish material remaining on the filter and cook it again to extract more glue, then repeat the filtering and concentrating.

Sources:

Encyclopedia of Chemical Technology. Paul I. Smith. Glue and Gelatine, Chemical Publishing Co., Inc., 1943. Thomas D. Perry. Modern Wood Adhesives. Pitman Publishing Co., 1944.