Animal glue is obtained by digesting animal bones, skin, tendons and other organs. The resulting substance acquires gluing abilities thanks to two substances - glutin and chondrin. The former is found in the bones, connective tissues, and skin of animals. Adhesives with a high glutin content have the best characteristics in terms of bonding surfaces. Chondrin is the main substance in the structure of cartilage. Glue containing a high concentration of chondrin does not have sufficient bonding strength.
Features
The purity and quality of animal glue depends on how thoroughly it was cleaned in production, as well as on the method of obtaining materials for the preparation of the adhesive.
In the event that mineral acids, caustic soda, lime, potassium chloride were used to make the glue, the substance obtained after cooking is unsuitable for use.
Checking the quality of animal glue
A quality glue solution after boiling should not change the color of litmus paper. When immersed in cold water glueshould swell, in hot water a quality solution dissolves.
Glue produced using the right technology should turn into jelly during cooling. Poor-quality substance with poor gluing abilities does not freeze. Also, cooled glue is not able to freeze if acid (acetic, hydrochloric, nitric) is added to it.
If the glue is kept on fire for too long, violating the production technology, it will also not freeze when cooled. The substance will not bond materials firmly enough.
The higher the cooking temperature of the glue, the faster it will be ready for use. For example, at 50 degrees, the solution should be boiled for 12 hours.
Adding lime to a solution of animal origin is unacceptable, since such an additive reduces the ability to stick objects together. In addition, the mixture quickly deteriorates, becomes moldy and rots.
Glue varieties from animal parts
Animal glue has many varieties and names: skin, skin, carpentry, painting, fur coat. They differ from each other in color and characteristics. Depending on the degree of purification, the color of the substance acquires a transparent, translucent, dark shade.
Animal skin glue
Skin glue is the most resistant to decay, but only if it is well cleaned. To increase the shelf life, phenol, salicylic acid and creosote are added to the mixture. To achieve elasticity, glycerin, sugar, and even honey are added to the composition. Due to its cheapness, animal glueused in the composition of paints for painting, creating scenery. Also, such glue is added to the primer. It is often used to glue furniture together.
Gelatin glue
Gelatin glue is obtained from the skins of young animals. The production of the substance is carried out in two forms - food and technical. The first type turns out to be absolutely colorless and is the purest type of glue in terms of composition. It is ideal for gluing those places where the joining point should remain invisible.
The disadvantage of gelatin is its small gluing ability compared to animal skin glue. One of its important advantages is its ability to be stored for a long time.
Fish glue
Produced from the swim bladder of cartilaginous marine life (sturgeon and beluga). Fish glue of domestic production is considered one of the best in quality. However, due to its high cost, this type of glue is practically not used in technology.
A good grade of adhesive is made from pure glutin. It has excellent astringency and elasticity, besides it has almost no color. Poor quality glue is made from fish waste (scales, bones, intestines, skin).
Milk glue
Obtained from a solution of casein in combination with fats. Sometimes the main substance is replaced with skim milk, which, when dried, dissolves in water. To avoid this effect, it is enough to add caustic lime to the adhesives of animal origin.
Use this substance to produce stretchy soil,plaster, as well as for fixing drawings.
Casein glue
This substance is obtained after souring dairy products. For the preparation of this type of glue, cottage cheese from fresh milk, which is pre-treated with a separator, is ideal. This is necessary because ordinary cottage cheese contains a lot of bacteria, fat and sugar.
To obtain the purest casein in production, the method of artificial curdling of milk with acids (hydrochloric or acetic) is used. The resulting technical curd is washed with water and then treated with soda or alcohol. The resulting glue is curdled again using acid. This process is repeated several times until a pure product without fats, bacteria and sugars is obtained.
An important advantage of casein glue is the fact that it does not dissolve in water.
Apply it in painting, making mineral paints. Due to its ability to emulsify oil and resin solutions, casein is often added to primers and tempera.
Animal adhesives in carpentry
Glues of animal origin also include substances used in carpentry. There are several varieties of them - mezdrovy, bone and mixed. Consider the production technology of these types of glue in more detail:
- Hide glue is obtained from the skins and hooves of cattle. To clean the material from dirt and grease, the waste is immersed in milk of lime, thoroughly washed and boiled at a temperature of 90 degrees. Received like thisIn this way, the glue is filtered and poured into dishes, where it is then evaporated and dried.
- Bone glue is made from ground animal bones. Fat is removed with gasoline. To get rid of particles of meat, the bones are immersed in hydrochloric acid. Then the components are boiled until jelly is obtained, the resulting mass is cut into plates and dried.
- Mixed gelatin glue is obtained by mixing skin and bone glues. By properties, such a substance resembles a fish type of glue, but mixed is much cheaper to produce.
Feature of wood glue application
Adhesive substances in furniture production are used only when hot. Before heating, tiles for gluing parts are soaked in water for up to 8 hours, while heating the water to 60 degrees.
In carpentry, glue from animal bones is used in various thicknesses. The fact is that soft wood needs to be glued with a thicker composition, but material from hardwood is securely joined with liquid glue.
If the need arises, the glue can be diluted in water or heated too liquid substance to obtain the required mass.
Albumin glue
Albumin composition is used in carpentry. It is obtained from the blood of a bull, which is previously cleaned of foreign substances, and then dried using a special technology. It differs from wood glue by good resistance to moisture, an easier method of preparation and excellent resistance to stress. This type of glue is used for the production of plywood. Albumin glue with addition of lime and ammonia is effective in application during wet gluing of wood.
Other types of substances used for gluing wooden structures:
- Glycerin glue is obtained by adding a small amount of glycerin to wood glue. Its positive qualities are resistance to heat, due to which it is used in places where temperature changes often occur.
- Chalk glue is obtained by adding some chalk to wood glue. Due to the transparency of the resulting substance, it is used for gluing wooden structures of natural color.
- Liquid glue syndeticone is obtained by adding acid (acetic, nitric or hydrochloric) to its composition. Its scope is gluing paper, leather, wood and porcelain.
Glue quality
Quality glue of animal origin should have a pleasant, not very pungent smell. Wood bonding agents with a bad smell are rejected because the protein decomposition process was disturbed during the production of the adhesive.
A high-quality composition for the production of furniture should not contain acids and fats. The water content should not exceed 17 percent of the total mass. The outer film should make a loud sound when struck.
Glue recipe
To prepare animal and vegetable adhesives, it is necessary to soaksmall pieces of the necessary components in ice water for 12 hours. After this procedure, the liquid must be put on fire, while the temperature should not exceed 50 degrees. In order to prevent the substance from burning, a special utensil for cooking is used, which is called kleyanka. It consists of two bowls of different sizes. A smaller one is placed inside a large vessel, then a large container is filled with water and placed on the hob. Pour the glue solution into a small container. As a result, the substance is cooked in a water bath.
