Why Does Wood Glue Turn Black?


Have you ever used wood glue and it suddenly turned black after it got dried? There’s a reason why this event happens. This article intends to provide you the most accurate answer to why does wood glue turns black, and some tips to prevent it from happening.

You will never resolve a problem if you don’t know the root cause of it. Wood glue turns black is not because of the wood nor the adhesive alone. It is a combination of both that transforms it into black when it gets dry. Some water-based emulsion glues contain an active amine that keeps them in suspension. The potent amine then reacts to any wood with high tannin content resulting in it to turn to dark. This case is the same with oak turned to gloom when wiped with ammonia. 

So if you’re ready, let’s dig more information on how to prevent wood glue from turning to black. This article also aims to help you choose the right adhesive for your project. We will also help you remove the dark spots caused by using wood glue.

How Can I Get Rid of the Stains Around the Glue Line Without Changing the Natural Color of the Wood?

There are some ways to eliminate the stains around the glue line. You can use sandpaper or a wood plane to get rit of the stains. You can also use a chisel over the dark spots of your workpiece. You can also try and apply acetone over the part where the glue got black. Use a cloth to wipe it on the affected area. 


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How Long Does Wood Glue Last?

If you are referring to the wood glue that you have already applied to a workpiece, it can last for a lifetime. It depends on how much glue you’ve put on. However, if you are talking about the unapplied wood glue, then its typical shelf life can last for up to 1 to 2 years. 

What Are the Kinds of Wood Glue?

The different types of wood glue are recognizable through their various colors – white, blue, or yellow. These differences in color signify uniqueness in the components of each wood glue for a specific application. Every type of wood glue that you can see on hardware stores has various chemical makeups, which allows them to work on particular surfaces.




  • Yellow Glue or Carpenter’s Glue. Most yellow wood glue is from a chemical called aliphatic resin. It is a little bit stronger than the regular white glue, but yellow glue dries faster. It also holds stronger. The best thing about yellow glue is that you can sand it over if you plan on repainting the area. However, please take note that it has a low resistance to wood stains.
  • Urea-formaldehyde Glue. It is a plastic resin glue that features water-resistant properties. It also has a high resistance to any paint and thinners. However, Urea-formaldehyde Glue is only ideal for indoor furniture. Regardless, this kind of glue takes approximately 30 minutes to get a good hold and firm grip on two surfaces.
  • Resorcinol Glue. It is the most durable type of wood glue, which is 100% waterproof. It is an excellent choice if you have to seal up or fix any outdoor furniture, concrete, or other heavy-duty repairs. In applying Resorcinol Glue, please keep it away from any moisture until it gets dry.
  • PVA Glue. It stands for Polyvinyl acetate, which is another common type of wood glue. It is colorless and odorless, which is widely available almost everywhere. However, you should not use it too much because any excess adhesive on your project may affect your finished quality. Hence, it may completely ruin the appearance of the project.
  • Epoxy. This kind of wood glue is the most popular. It consists of two parts, which includes a resin and a hardener. They are both liquids but produces a new chemical reaction that can harden when mixed. The most significant advantage of using epoxy is that they are 100% waterproof, and it is excellent in filling the gaps to match joints perfectly.
  • Polyurethane Glue. It dries quickly and very hard, which makes it ideal for almost any kind of project – big or small. Polyurethane Glue is also suitable for both indoors and outdoors. However, dried polyurethane glue can be problematic for finishes whet it dries. So, wipe the area with a wet cloth before applying polyurethane glue. Then, clamp the pieces together right away for at least 24 hours. Use mineral spirits to clean off any excess polyurethane glue.
  • Hide Glue. The name is kind of intriguing, but it does come from animal hides. There are two types, which include hot hide glue and liquid hide glue. The first kind came from heated granules, and the latter comes in a bottle. Unlike PVA, hide glue does not affect the finish of your project in case you forget to remove the excess adhesive.
  • Cyanoacrylate Glue. It is the best glue for joining thick pieces the fastest time as possible. You can also use an accelerant to speed up the gluing and drying process. 

What are the Similarities of White Glue to Wood Glue?

White glue is the most basic adhesive that can hold small surfaces. It is the kind of glue that you’ve probably first held in school. It came from waste byproducts of animals such as bones, ears, hooves, and tails. Then, these byproducts combine with zinc oxide until it begins to produce a glue-like substance.

One common denominator between wood glue and white flue is that they are both from animal byproducts. They only differ with the processing of different types of chemicals to achieve the end product adhesive strength.




Which Type of Wood Glue to Choose?

Choosing the right kind of wood glue for your project can be intimidating with the different choices out there. It becomes a tough job because all the wood glue mentioned above provides sturdy support for most projects. So, it’s all about the other unique characteristics. For example, do you prefer to have waterproof wood glue? For how long do you want to work with the glue before it starts to harden? Do you need glue to fill a gap?

The answer to the questions mentioned above will help you determine the right kind of wood glue for your project. For example, PVA Glue is widely available in most hardware stores. On the other hand, epoxy glue is a good choice if you need it durable and water-resistant. So, convenience in buying is never a problem. However, can you work with its pros and cons? The choice is always yours. Take your time in picking the right wood glue, and weigh all their advantages and disadvantages.

What Is the Best Way to Disassemble a Wood Glue?

The best way to disassemble glued joints is to weaken the Bond by raising the glue joint temperature. You can use a heat gun, a blow dryer, or steam from boiling water. The heat reduces the glue’s strength. If the wood glue is not waterproof, you can use a few drops of water or acetone on the edge of a joint.




How Do I Clean Up Wet Glue or Remove Dried Glue?

For most water-based wood glues, you can use a damp cloth or apply drops of acetone to remove excess adhesive before it gets dry. Otherwise, if it has dried, scraping or sanding works well. 

FREQUENTLY ASKED QUESTION

What Is the Assembly and Cure Speed of Instant Bond Glues?

Usually, the Assembly and Cure Speed of Instant Bond Glues depends on the brand and the material that you currently have. Generally, thin Assembly Time is approximately is as follows:

  • Flat Assembly Time: 5 seconds Cure Speed
  •  Medium Assembly Time: 7 seconds Cure Speed
  • Thick Assembly Time: 10 seconds Cure Speed
  • Gel Assembly Time: 30 seconds Cure Speed

What If Instant Bond Doesn’t make Bond?




There should be a problem with how you worked on the wood glue. You have to make sure that the surface is clean and dry unless you intend to glue up dust or dirt on the surface. Before applying the glue, you can use water or a small amount of acetone until the area is clean.

How Do I Remove Wood Glue from My Skin or Project?

You can use and apply a small amount of acetone over the affected area. Then, rub it off until you remove the adhesive. Also, you can use a nail polis remover as well. Make sure to follow the solvent’s precautions. Be careful in applying because these items are flammable and may irritate your skin or may cause other reactions to your project.

Final Words

As you know, wood glue turns black because of the incompatibility of its components with the wood. It is a combination of both that transforms it into black when it gets dry. More often, you can eliminate those dark spots through the use of acetone or nail polish remover. However, be sure that it will not cause any other reaction to your wood. 


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