1. Sourcing and Preparation:
* Fish Selection: Fish like cod, haddock, hake, and sturgeon are commonly used due to their high collagen content.
* Cleaning and Processing: The fish parts are cleaned, washed, and sometimes pre-treated to remove impurities.
2. Extraction:
* Boiling and Dissolving: The fish parts are boiled in water for an extended period, typically several hours. This process breaks down the collagen into gelatin.
* Filtering and Clarifying: The resulting solution is filtered to remove any solids and impurities. It may also be treated with chemicals like alum to clarify the glue.
3. Concentration:
* Evaporation: The liquid is concentrated by evaporation, either through boiling or using other methods. This increases the concentration of gelatin.
4. Drying and Shaping:
* Drying: The concentrated solution is dried into a solid form, usually by spreading it in thin layers and allowing it to dry in a controlled environment.
* Shaping: The dried fish glue may be shaped into sheets, flakes, or other forms depending on the intended use.
5. Refining and Packaging:
* Grinding and Powdering: The dried fish glue may be ground into a powder for easier use.
* Packaging: The fish glue is packaged for storage and distribution.
Properties and Uses:
* Strong Adhesive: Fish glue is known for its strong adhesive properties, especially when used on porous materials like wood.
* Water-Soluble: It dissolves in water, making it easy to apply and remove.
* Traditional Applications: Historically, fish glue has been used in bookbinding, furniture making, and other crafts.
* Modern Uses: Fish glue still finds niche applications in certain industries, such as fine woodworking, instrument making, and some specialized adhesives.
Note: While fish glue was once a common adhesive, its use has declined with the development of more modern alternatives. However, it's still prized for its unique properties in specific applications.