Wood Glue Buying Guide...
Gums and resins from trees were the very first glues used and archeologists have found examples dating back over 150,000 years. Up until very recently glues were made from natural products such as collogens from animal skins and casein from milk. Advancements in chemistry and the petro-chemical industry saw the development of a whole host of synthetic polymers and plastics, some of which form the basis of the modern wood glues that are extremely popular today.
Anatomy of Wood Glue
How and why glues work is still a question that is yet to be answered in full and scientists are still researching the processes of adhering one surface to another in order to completely understand it.
The simplest explanation offered is that, on a microscopic level, no surface is perfectly smooth and when an adhesive is applied to that surface all of the pores and imperfections in the surface are filled with the adhesive.
Being able to permeate the surface gives the glue something to "hold on" to so when it dries it forms a solid bond with the surface it is applied to.
This is only one part of the story though. Not only does the glue have to form a solid bond with the wood, paper, fabric or any other substrate it is designed for, the glue molecules also have to stick to each other.
It is this combination of cohesion, how the glue molecules stick together, and adhesion, how the glue molecules stick to other substances, that allows glues and adhesives to work so successfully. ©
Types of Wood Glue
One of the most commonly used glues for woodworking, polyvinyl acetate (PVA) is also referred to as white glue and craft glue. PVA is water based and formulated for use on porous surfaces such as wood, paper, fabric etc. Offering an open time of around 5 minutes, this glue gives plenty of time for joint assembly. Any excess can be cleaned off with water whilst wet or sanded when dry. Curing time usually takes around 24 hours. PVA glue joints have a tendency to creep under continuous load and are not suitable for structural applications. ©View our Range of PVA Glue
Cyanoacrylate glue is the official name for instant and super glue. Capable of bonding both porous and non-porous surfaces, cyanoacrylate glue is perfect for adhering metal bandings and decoration to wood. It is also a favourite with woodturners for attaching work to sacrificial pieces of wood when chucking. Available in various consistencies, from water like with a cure time of less than 10 seconds to gel like with a cure times in excess of one minute, cyanoacrylate glue is also used for gap and crack filling in wood. These glues use moisture in the air and in the substrate to cure. ©View our Range of Cyanoacrylate Glue
Polyurethane glue is an excellent all purpose glue and will bond almost any material with the exception of some plastics. Water resistant and solvent resistant once dry, Polyurethane glues are ideal for outdoor as well as indoor use. Unlike the PVA based glues, polyurethane foams up and expands when curing. This expansion makes it a superior glue to PVA based glues when gluing end grain. Polyurethane glue has an open time of around 10-15 minutes giving plenty of time for assembly and requires a clamping time of around 1-2 hours. This glue cures in around 24 hours. ©View our Range of Polyurethane Glue
Cold Press Veneer Glue
Formulated specifically for veneering, cold press veneer glue is for use when bonding real wood veneers to a porous substrate such as wood, chipboard and MDF. As the name suggests, cold press veneer glue requires no heat to cure and can be used at room temperature. Most veneer glues are PVA based but unlike PVA will not bleed through the tiny holes found in open grained woods. Veneer glues offer long open times of around 15 minutes allowing plenty of time to position the veneer. Due to its composition, cold press veneer glue is suitable only for veneering. ©View our Range of Cold Press Veneer Glue
Similar in its use to cold press veneer glue, melamine glue is formulated to bond non porous materials such as high pressure laminate, vinyl, melamine and even metals to porous surfaces such as wood, MDF and chipboard. Melamine glue has a strong initial tack and an open time of around 5 minutes. PVA based, melamine glue can be used at room temperature and does not require any heat to be applied to it in order to cure. ©View our Range of Melamine Glue
Moulding & Trim Glue
Moulding & trim glue is designed for adhering dado rails, baseboards, casing and other similar trim to walls. Exceptionally viscous, this type of glue is formulated not to run and will bond porous and semi-porous materials. Designed for vertical use, moulding and trim glue has a strong initial tack, giving almost immediate adhesion, and an open time of around 5 minutes. ©View our Range of Moulding & Trim Glue
Features to Consider When Buying Wood Glue
1. Open Time
The open time of the glue refers to the time available from the glue coming out of the bottle and being applied to the wood before it begins to cure. This is the maximum amount of time you will have to assemble the parts being glued. Also known as open assembly time. Some glues state a closed assembly time and this refers to the recommended amount of time the joint needs to be clamped for. ©
2. Curing Time
The curing time gives an approximate time taken for the glue to dry fully. Many factors can influence this figure such as heat, humidity and the types of substrates being glued. Heat in certain cases can decrease curing time whilst high humidity can either lengthen or shorten curing time depending on the type of glue. Curing times can vary wildy from a few minutes for a cyanoacrylate glue to several days for an epoxy resin. ©
3. Bond Strength
Different glues are suitable for different types of bond. PVA and aliphatic resins offer a stronger bond than polyurethane glues when gluing long grain to long grain. Polyurethanes excel at gluing any joint involving end grain as they soak in to the wood but do not cause it to contract during the curing process. For structural strength epoxy resin is the adhesive of choice. It is worth looking at the types of joints used in a project before selecting the type of glue to use. ©
Tips From the Experts
1. Do not over glue a joint. Aim to get fine beads of squeeze out when the joint is brought together. Any more glue than this coming out and you have used too much glue. ©
2. Storing glue brushes in a sealed container or bag will prevent them from drying out and keep them ready for use. ©
3. Glue has a shelf life. When you open a fresh bottle of glue write the date it was opened on the bottle. This will allow you to keep track of the life span of the glue. ©
4. If two surfaces refuse to bond with cyanoacrylate glue, moisten one surface slightly and try again. The water helps the glue to cure. ©
5. Try to remove excess glue whilst still wet. Dab away the excess as rubbing will drive the glue into the pores of the wood and could effect the quality of the finish. ©
Titebond have been producing professional quality wood glues since 1935. From their pioneering ready to use Liquid Hide Glue to their industry leading Original Wood Glue, Titebond offers a broad spectrum of adhesives to suit many different workshop applications. Extremely popular, Titebond is a brand trusted by woodworkers all over the world.View our Range of Titebond Glue
After use, squeeze any excess air out of the bottle or container. Many glues rely on evaporation or moisture to cure and removing the air should prevent this from happening. ©
Never use a glue that has changed consistency from its original state. This could indicate that the glue has gone past its shelf life and may not perform as expected. ©
To extend the shelf life of cyanoacrylate glue, unopened bottles can be stored in the refrigerator. ©
Always follow the instructions on the bottle. ©