Wooden glue is the glue used to tie tight pieces of wood. Many substances have been used as adhesives.
Video Wood glue
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Animal gels, especially glue hides, are the main adhesive of choice for many types of woodworking, including furniture and lutherie, for centuries. It is made from collagen given from the skin (skin) of the animal. Chemically similar to edible and non-toxic gelatin when ingested. Hide glue is still used today in special applications: musical instruments (lutherie), for replica furniture, and for refurbishment of conservation classes for antique wood. Hide the glue is measured by the strength of the gel, the size of how many grams of strength it takes to press 1 / 2 in (13 mm) plunger 4 mm (0, 16 in) into a 12.5% ​​protein solution of the glue at 10 ° C (50 ° F). The glue is produced in a standard grade of 32-512 grams (1.1-18.1 oz). The 192-gram strength (6.8 oz) is the most commonly used for woodworking; 251-gram (8.9 oz) is the highest normally used for building instruments; 135-gram (4.8 oz) is the lowest used for common woodwork. Glue above 250 grams (8.8 oz) of strength requires excessive dilution and so leaves too little glue on the joints for effective adhesion, so it is not commonly used. Liquid versions of glue hide are now available; Usually they have urea added to keep the liquid glue at room temperature and to prolong the drying time. Examples of liquid cleaning glue are Old Brown Glue or Titebond Liquid Hide. Hide glue does not creep. Hiding glue joints is easy to repair, simply by heating and adding more adhesive glue.
Urea-formaldehyde
The urea-formaldehyde resin adhesives have a low cost effective, low healing temperature, resistance to microorganisms and abrasion, and light colors. It does not crawl, and can be fixed with epoxy. It can rapidly deteriorate in hot and humid environments, releasing formaldehyde (carcinogens).
Resorcinol-formaldehyde
The resorcinol-formaldehyde resin gels are very strong and durable (hold immersion in boiling water, mild acid, salt water, solvents, mold, ultraviolet, etc.). It should be mixed before use (liquid resin and catalyst powder). It has a deep purple color, which may be inappropriate in some uses. Poison. For years, the Federal Aviation Administration (FAA) has stated that "Resorcinol is the only known adhesive that is recommended and approved for use in wooden plane structures and fully meets the required strength and durability requirements" for certified aircraft. In reality, however, most of the wooden planes built in the last few decades (mostly amateur-made aircraft) use other types of adhesives (especially epoxy resin systems), which offer greater strength and, more importantly, less criticality in applications perfect. technique. Most newer adhesives are much more tolerant of typical construction faults (such as small gaps or misalignment between parts) of resorcinol, which offer almost no tolerance for such everyday construction situations. This can cause great difficulties, especially in complex assemblies. Resorcinol, however, is still used by some builders/restorers, and is generally seen in vintage planes.
Phenol formaldehyde
Phenol formaldehyde resins are commonly used to make plywood. It heals at high temperatures and pressure.
Polyurethane
Polyurethane glue (trade names including Gorilla Glue and Excel ) are becoming increasingly popular. They bind textile, metal, plastic, glass, sand, ceramic, and rubber fibers, in addition to wood. Polyurethane wood adhesive is usually a prepolymer terminated with an isocyanate group. When exposed to moisture, the isocyanate reacts with water and thereby heals the adhesive. Therefore, one polyurethane adhesive component is also named a water-moisturizing polyurethane. In addition, the interaction between polyurethanes and wood polymers can significantly affect the bond performance. However, in water saturation tests, the polyurethane bond is "much more durable than the resorcinol bonds on both [Douglas-fir and yellow birch]."
Epoxy
The epoxy resin, usually as a two-part mixed system, heals under a wider range of temperatures and moisture content than any other glue, requires no pressure during pickling, and has a good gap fill property: actually produces weaker bonds. The use of epoxy requires special attention to the two-part mixing ratio. This bonds with the most preserved wood adhesive (except PVA). Two parts epoxy adhesive is highly resistant to brine, most of heat-resistant epoxy up to 350 Â ° F (177 Â ° C), formulations containing powdered metals and rubber or plasticizer are extremely hard and shock resistant. Epoxy can trigger long-term sensitivity (allergies) from overexposure, and is often expensive.
Cyanoacrylate
Cyanoacrylate ( Lem crazy , Superglue , CA or CyA ) is used primarily for minor repairs, especially by woodturner. It's a direct bond, including to the skin. The cured CA is essentially a plastic material. Versions available that can blend into tight joints but are attached to reduced strength (as many drip out and soak into the wood leaving very little on the surface for bonding), or a thicker formulation (gel) that can fill a very gap small, do not drain out of the joint, and do not soar into the wood. The thinner cyanoacrylate gels do not bind faster or form shorter polymer chains than gel versions when used on wood. The chemical nature of wood significantly delayed the polymerization of cyanoacrylate. When finally polymerization in wood joints, enough gel is left for better bonding than with thin versions. When using a gel, too much glue will weaken the resulting bond. Likewise, the use of too little superfluous glue will produce almost no glue at all in the wooden joints, causing weak bonding or no bonding at all. Also available versions are safe foam (common CA dissolves most plastic foams) which are usually also marketed as low-odor . Cyanoacrylate is rigid but has low shear strength (brittle) so that normal wood bending can damage the bond in some applications. Often, too much adhesive is applied which leads to a much weaker bond. CA quickly became the dominant adhesive used by balsa wood model builders, where its strength far exceeded the base material.
Casein
Case glue is used to make strong and strong connections at the start of the flight, but is not preferred because of its susceptibility to bacterial attack.
Polyvinyl acetate
Polyvinyl acetate (PVA), also known as "white glue" or "hobby and craft", is non-toxic and very easy to use, but is difficult to repair as most glue (including PVA itself) is not well attached to the hardened PVA glue.. PVA will creep under a constant load. Elmer's Glue-All is an example of PVA adhesive.
Aliphatic resin
Aliphatic resin emulsions, commonly referred to as "yellow glue" or "carpenter glue", have similar usage profiles and relative end strength as PVA. Both glue differ in grip characteristics before the initial set, with PVA showing more slippage during assembly and yellow glue having an earlier grip. Brands include Titebond and Lepage .
Contact cement
Contact cement for wood veneer.
Hot glue
Hot glue for temporary use.
Homemade
Homemade lugs for paper, wood, and internal use.
Maps Wood glue
Usage
Some wooden adhesives have a poor "filling gap" ability, which means they seep into the wood and leave the gap empty, or keep filling the gap but have little structural integrity. Therefore, carpenters usually use tight connections that require a bit of a startling glue to withstand large pieces of wood. Most wood glue needs to be clamped while the glue is installed. Epoxy resins and some other adhesives can be thickened with structural fillers (or with thicker resin formulations) to help fill the gap, but it is better to try to minimize the gap in the first place.
Mechanical resistance
Fine Woodworking magazine runs a number of tests to evaluate the mechanical resistance of wood joints with different glue:
See also
- Clamp (tool)
- Carpenter
References
Source of the article : Wikipedia
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