Glue is a mixture or substance, as well as various multi-component compositions, made on the basis of both inorganic and organic substances that are popular today. It is able to connect a variety of materials: paper, fabrics, leather, wood, ceramics, glass, rubber, metals, plastics. Bonding is caused by the formation of an adhesive (very strong) bond between the surfaces to be joined and the adhesive layer. The strength of adhesive joints is also affected by cohesion to the surface of the adhesive. According to the type of bonding, adhesives are classified into drying, non-drying adhesives and binders, which are based on polymerizable compositions.
Consider the drying type (its characteristics), namely wood glue. It includes: casein, glutin, PVA, vegetable glues and glue masses from synthetic resins.
Casein carpentry glue is a brown-yellow powder. It is made from alkali and dry fat-free cottage cheese. When preparing this powder, pour it into non-cold (room temperature) water and stir constantly.
Ratio - 2:1 (water to powder). In terms of its properties, it is inferior to fish, but it is superior to the flesh one.
Glutin wood glue is made from mezdra (animal skins, tendons, cartilage), fish and animal bones. It is divided according to the types of substances underlying it: bone, fish and mezdrovy. Fish is mainly used for various restoration work, and bone and mezdrovy, as a rule, in working with furniture. Most often, glutinous wood glue is produced in the form of small dry tiles. Sometimes it happens in barrels, but in this form it quickly rots. It is advisable to prepare the adhesive solution for one to two days. It is important that leftovers are kept refrigerated. The quality of a tile is determined by its external state - if it does not bend, does not give sharp edges when broken and has a transparent color, then this is a good tile. Conversely, the dark color of the tile, chipped edges and the ability to bend it easily indicate low quality. Preparation: the tiles must be poured with boiled water, cooled to 25 degrees, and wait 10-12 hours until they swell. If you pre-crush the plates into pieces, you can reduce the swelling time to 2-4 hours. Swollen glue should be boiled for three hours. To avoid rotting glue, you can add antiseptics when cooking. When gluing, first smear the surfaces and give them exposure (5 minutes). Then the parts are connected and wait another 5 minutes. After they are placed under the press for a day.
PVA wood glue is produced in tubes ready for use. It is not washed off with water, dries quickly, but, unfortunately, has a short shelf life. Despite this fact, at the moment it is the mostcommon among other species.
Vegetable wood glue has not found wide application due to weak bonding properties. It is mostly made from starch and is used to bond cloth and wood surfaces.
Glue masses from synthetic resins are liquid and pasty. They are suitable for wood, and for cast iron, and for porcelain. Most often made from carbinol.