How Long Does Wood Glue Take To Dry?
At the beginning of our woodworking journey we all had put glue on two pieces of wood to stick them together and wondered “how long does wood glue take to dry?” We all want to just fast forward this waiting part and get on and finish our masterpiece.
Wood glue takes somewhere from 5 minutes to 24 hours depending on what type of glue you have used, density or porosity of wood, moisture content of the wood, the relative humidity of surrounding air and clamp pressure. A typical yellow glue known as wood glue or carpenter’s glue would take between 12 to 24 hours to dry whereas a Super glue can get the job done in less than 5 minutes. Higher the moisture content, longer would be the drying time of the glue. With a higher relative humidity it would take much longer for the glue to dry whereas a high clamp pressure would lead to a faster drying time. This time taken by wood glue to properly dry is also called Cure Time.
With the above concept in mind let’s delve a bit deeper into this topic. Let’s see how we can minimize the time taken for glue to dry so that you can quickly get on with your next steps.
How Does Wood Glue Dry?
Wood glue is made up of varieties of a type of chemical called polymers. These polymers use water as a solvent to stay liquid till the time we use them to stick two pieces of wooden surfaces together. When glue is put on a surface of wood, it gets exposed to air. This causes the solvent, which is water, to start evaporating from the glue. As the water evaporates, the polymers, which are long strands of molecules, start intermingling with each other which hold things together. This process is called mechanical adhesion.
What Factors Affect Glue Drying Time?
There are 5 primary factors which impact glue drying times:
1. Type of Glue used
Different types of glue has different applications and hence different drying times. White glue, which is used in small diy projects requiring light weight wooden pieces to join together have a much lesser drying time than the yellow carpenter’s glue which is used to join heavier pieces in a furniture.
Here are the 6 most popular types of glue and their drying times:
- PVA (Polyvinyl Acetate) Glue – This is one of the most common variants of glue available in the market and comes in white color. It is used in hobby woodworking projects and generally dries within 30 minutes to an hour.
- Aliphatic Resin Glue – This is also known as “yellow glue” or “Carpenter’s glue” and as the name suggests can be used on wood, hardboard, high-pressure, laminates, particleboard, leather, supported vinyl, cloth, paper and many other porous materials. Yellow glue requires at least 12 hours to fully cure and dry.
- Cyanoacrylate Glue – Also known as Superglue or Crazy Glue, it bonds instantly, including to skin. In woodworking, superglue is used to temporarily hold wood mounts in place for nailing, screwing or other types of fastening to happen.
- Epoxy Glue – This uses a resin and a hardener to mix together to form the bond. It cures under a wider range of moisture and temperature and does not need pressure. Mostly used in filling wood gaps, this glue generally takes up to 24 hours to reach 95% of full cure and 72 hours to 100% cure.
- Polyurethane Glue – There are known in the market as Excel or Gorilla Glue. Gorilla glue is one of the strongest glues available and is resistant to water, heat and cold. It can be used to bond wood with metal, glass, ceramic, foam and many others. One the glue cures it can be paintable, stainable and sandable. Gorilla Glue generally takes 1-2 hours to reach 80% cure and up to 24 hours to 100% cure.
- Animal Glue or Hide Glue – It is made from the collagen present in the hides of animals and has been used in musical instruments, replica furniture and in antique woodwork. Hide glue generally takes 24 hours to reach full strength.
2. Wood Density or Porosity
For a glue to properly bond two pieces of wood together, it needs to be in contact with both the surfaces for a suitable period of time.
A more porous wood would absorb the glue within itself and would not allow it to come in contact with the other surface. Hence you will need a lot more amount of glue and time to join the two surfaces together.
A denser wood on the other hand would not absorb the glue within itself and would require lesser glue to do the job. This in turn would lead to lesser drying time as lesser water needs to be evaporated from the glue for it to cure.
3. Moisture Content of Wood
Wood with higher moisture content would delay the process of drying of the glue. Glue dries when the water inside it evaporates both in the air and within the wood. With a wetter wood the evaporation within wood gets minimized and hence lead to longer drying times.
4. Relative Humidity of Surrounding Air
In much the similar phenomenon as the previous factor, a humid environment would not be able to evaporate water from glue quickly and would lead to longer curing time. Ideal relative humidity for proper curing of wood is 40% – 60%.
5. Clamp Pressure
Clamp pressure should not be too high as to crush or deform the wood. The clamp pressure should firmly hold the two pieces together. A high pressure would lead to the glue escaping from the side and a weaker joint, although the drying time would be fast. A low pressure would lead to the surfaces not coming in proper contact with the glue and would lead to a weaker joint as well as a slow drying time.
What are the ideal conditions for glue to dry faster?
Given wood density and type of glue chosen for the purpose, I have found the fastest drying times are achieved when the moisture content in the wood is around 6% to 10%, a relative humidity of around 40% to 60% of the surrounding air and temperatures of around 70F to 80F.
It is not very easy to judge the relative humidity in your workshop or the actual moisture content in the wood. As a rule of thumb, if you are sweating a lot inside your workshop or if it is raining outside, it would not be a very ideal condition for the glue to dry faster as the relative humidity of the air would be much higher than 60%. This in turn would also lead to increased levels of moisture content in the wood.
When should you prefer a fast drying time vs slow drying time?
Of course everyone would prefer a faster drying time over a slow one! But you need to be cognizant of the importance of the woodworking project. A hobby project of replica furniture can do with a fast drying without 100% curing happening. But a full-blown furniture project or a housing project which would eventually require the joined surfaces to go through a lot of stress and pressure needs proper curing to happen. In this scenario it is always better to keep your patience and let the glue dry properly before proceeding with the next steps. You can be extra cautious in this scenario and give it a bit more time than what is required.