Bone glue
Bone glue
EXPERT KNOWLEDGE BONE GLUES
Animal and vegetable glues have been used for more than 4000 years to join materials such as wood, leather and paper. One of the most traditional and still highly valued glues is Bone Glue, a special glutinous glue made from animal waste, mainly bones, which offers numerous advantages for specialised uses such as musical instrument making and the restoration of antique furniture.
Production of Bone glues
Bone glues are based on animal waste products, particularly bones, which contain a high proportion of collagen, a protein that is converted into glutin through special processes. The process is similar to the production of gelatine, but it is prepared for consumption. While gelatine is clear and tasteless, bone glues are produced in a more intensive process with specific properties for adhesive use.
The bones are first cleaned, cooked and extracted several times to obtain the glutin. After drying, a solid granulate is produced, which is often sold in the shape of pearls or pearl barley. The typical packing unit comprises several kilograms, allowing craftsmen and restorers to process their materials efficiently.
Difference to Hide glues
Bone glues and Hide glues both belong to the family of glutin glues and have similar properties. The main difference lies in their origin and their viscosity. While Bone glues are obtained from solid, bony structures, Hide glues come from animal skins and connective tissues. Hide glues are therefore often softer and have a higher elasticity, whereas bone glues enable particularly hardness. This strength makes it ideal for uses where stability and sound transmission are crucial, such as in the construction of musical instruments.
Areas of application for Bone glues
Bone glues are an indispensable wood glue, especially in craftsmanship and restoration. Its unique property of reversibility - it becomes soluble again with water and heat - makes it ideal for:
- Musical instrument making: thanks to its glass-hard drying, bone glues transmit sound waves excellently and ensure precise sound in stringed and plucked instruments.
- Furniture restoration: Old techniques and materials often require the use of traditional adhesives such as Bone glues to preserve historical integrity.
- Veneer work: It ensures a thin and stable bond that can be easily removed if necessary.
Bone glues are also occasionally used in bookbinding and leatherwork.
Processing Bone glues
The processing of bone glues requires a certain amount of preparation and care. In its standard commercial form, often as beads, it is first soaked in water and then heated in a water bath. The resulting glue mass has a typical viscous consistency that should be neither too thin nor too thick - comparable to viscous honey.
Preparing the glue:
- The Bone glues beads are placed in a glass container.
- Hot water (not over 70 Garde load speed) is added so that the beads are completely covered.
- After a soaking time of several hours, the glue is slowly heated in a water bath until it is evenly liquid.
Preparation of the workpieces:
Before gluing, the surfaces must be clean, free of grease and, if necessary, slightly heated, as this improves the adhesive strength. Especially with oily woods such as teak, it is advisable to degrease the surfaces with acetone or Alcohol content.
Glueing with Bone glues:
The glue is applied quickly and evenly, as it hardens quickly as soon as it cools down. It is advisable to assemble and fix the workpieces immediately after application to ensure a stable bond. Excess glue can be removed with a hot, damp cloth.
Advantages of Bone glues
- Reversibility: Bone glues can be dissolved by water and heat, making them ideal for repairs.
- Hardness and stability: After drying, the glue line becomes as hard as glass, resulting in a very strong bond.
- Wide range of applications: Wood, leather, paper and even other materials can be glued stably with Bone glues.
- Natural: As a traditional, animal-based adhesive, it is free from synthetic additives.
Disadvantages and limits
Despite its numerous advantages, there are also some limitations:
- Water sensitivity: Bone glues are not waterproof and are therefore only suitable for use in dry indoor areas.
- Complex processing: Production and use requires time, care and experience.
- Fast hardening: The glue hardens in a few seconds when it cools down, which makes it necessary to work quickly.
Comparison with other glues
In addition to bone glues, there are also Rabbit skin glues, which also belong to the glutin glue family. Rabbit skin glues are obtained from animal skins, especially from hares, and are somewhat more elastic than bone glues. Both adhesives are reversible and offer excellent bonding properties for traditional crafts. Modern wood glues such as white glue or polyurethane glue, on the other hand, are often Waterproof, but not reversible, which limits their use in restoration work.
Detachment and storage
One of the greatest strengths of bone glues is their ability to loosen joints. Thin workpieces can be easily separated by heat and moisture. However, thicker material cross-sections require the use of a steam iron or lengthy soaking.
Mixed Bone glues will keep for a few days as long as they are kept cool and covered. Dried glue can be reused by reheating, making it extremely sustainable.
Working with Glue Pots
A high-quality glue pot is used in the professional processing of animal glues. The Herdim Glue Pots from DICTUM impress with their precise temperature control and robust design. Thanks to a control thermostat with an accuracy of ±3 Garde load speed, the glue is gently heated to the desired temperature - ideal for glutinous glues, which are typically processed at 60-70 Garde load speed. The nickel-plated brass housing ensures a long service life, while the heat-resistant plastic handle and non-slip base plate provide safety and comfort during handling.
These devices are specially designed for continuous operation and have proven themselves in areas such as restoration, woodworking and musical instrument making. The uncomplicated operation enables versatile use. Additional accessories such as spatulas, brushes, storage containers and spare parts are available for the various models.
Bone glues are more than just a traditional wood glue - they are a symbol of craftsmanship, precision and sustainability. Compared to modern adhesives, its hardness and reversibility offer unrivalled advantages for specific uses, especially in musical instrument making and restoration. For craftsmen who value authenticity, Bone glues remain an indispensable tool whose use is justified by its versatile and reliable properties.
