How to Thin Wood Glue – 4 Quick & Easy Fixes

Wood glue is a great tool and the most commonly used glue by woodworkers and many other professions or hobbies. It is a strong adhesive that sets relatively quickly. However, the adhesive tends to thicken over time or due to circumstances.

When you have thickened wood glue, you can, in most cases, thin it again without losing strength or effectiveness. In this article, you will learn how to thin wood glue.

To dilute thickened PVA wood glue and make it usable again, you can add 5% water to the volume. Other techniques are adding a few drops of vinegar, diluting it with 1 part rubbing alcohol to 8 parts wood glue, or slightly warming up the wood glue to change the viscosity.

Although the solutions for thickened wood glue seem simple, there are a few important things you need to know, which I will tell you about in this article.

For example, not every wood glue can be diluted, and you will have to choose to throw it away and get started with new glue.

By reading this article, you will understand all the basics of wood glue and why wood glue thickens, and how to keep it from thickening. You’ll know how to thin wood glue the right way in just a few moments!

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What is PVA wood glue?

Most woodworkers are familiar with PVA glue, which stands for “polyvinyl acetate.”
This is the well-known white wood glue that dries colorless and has the consistency of a paste.

In addition to polyvinyl acetate, PVA wood glue contains other ingredients.
The ingredients of wood glue may vary from brand to brand, but the ingredients present in Titebond wood glues include water, vinyl alcohol, and aluminum chloride.

Now that you know which are the most common ingredients, later in this article, you will also better understand why wood glue can thicken and what we can do to slow down or undo this process.
Also check out other glues used in woodworking in my article 8 Different Types Of Woodworking Glues – A Clear View On Wood Glues

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What Makes Wood Glue Thicken

Perhaps the biggest factor in thickening wood glue is improper storage. Wood glue has a technical shelf life of one to two years, but in ideal conditions, it can be used for much longer, up to 10 years. Proper storage can extend the life without diluting it.

Storing wood glue incorrectly will cause the moisture present in the wood glue to evaporate, making the glue thicker and eventually unusable.
Here are a few situations that will speed up this evaporation.

Heat. If your wood glue has been stored in a room that is too warm, the high temperature will allow the moisture to evaporate.
Cold. It may sound strange, but temperatures that are too cold also increase the evaporation of moisture.
Air. Air will draw moisture from the wood glue when exposed to it.

How to Prevent Wood Glue from Thickening

As the list above shows, a number of factors can cause wood glue to thicken fast. However, you can prevent wood glue from thickening by following the easy methods outlined below.

  • Before sealing the bottle, squeeze out as much air as possible.
  • Always keep the bottle tightly closed.
  • As I said before in this piece, you may keep the bottle in the fridge to prevent the adhesive from solidifying.
  • Is your garage filled with frozen wood glue throughout the winter? The wood glue should then be stored in an insulated cabinet or carried with you during the winter.
  • Also, keep in mind that excessive heat may cause the adhesive to dry up.

Methods of Thinning Wood Glue

Has your wood glue thickened? Don’t worry, the tricks below will teach you how to thin wood glue, so you can use it again.

Please note, thickened wood glue will not always be reusable. This type of glue can be in such a state that thinning wood glue will no longer work, and you will have to throw it away. More about that later in this article. Now, I will first show you how to thin wood glue.

how to thin wood glue with water

Simply adding water is one of the best-known methods of thinning wood glue. Water-based PVA wood glues can be easily thinned by adding water.
But be careful, you should not add too much water.

You can add a maximum of 5% water to the total amount of glue that you want to dilute. However, if you add more water than the appropriate 5% by weight or volume, this can reduce the bonding strength and effectiveness of the wood glue.

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how to thin wood glue with heat

Heat can make wood glue thicker due to the evaporation of water in it. So you will not immediately link this tip with thinning the glue, and yet it is a good tip.

Wood glue can be thinned by gently warming the bottle in warm water.
What will happen is that the viscosity of the glue will change, making it temporarily more liquid.

When using this trick, be careful not to get the reverse effect. If the glue will be heated too long or the water gets too hot, the moisture will evaporate from the glue, and it will tend to solidify.

To thin the glue by means of heat, proceed as follows:
Heat a pan with water, but don’t let the water get too hot. Body temperature is a good guideline for the heat of the water. Once the water has reached the right temperature, you can place the bottle with wood glue in the warm water. Check it regularly to see if the wood glue is thinning. It may take a few minutes for the results to appear. This trick is best suited for diluting hide glue, but it can also be used with PVA adhesives.

how to thin wood glue with alcohol

This is a trick I learned in the hobby of model train building. Wood glue is also often utilized in the construction of model train scenery. Wood glue, on the other hand, is frequently overly thick, and modelers will dilute wood glue with rubbing alcohol.

It could be sufficiently diluted by mixing 1 part rubbing alcohol with 6 parts wood glue. When diluting thicker wood glue in woodworking, I would start with 1 part rubbing alcohol to 8 parts wood glue. You can add more rubbing alcohol if it’s still too thick.

When you glue with this combination, the alcohol will immediately evaporate, leaving only the adhesive. This would speed up the curing process slightly. Some people advocate adding a few drops of dish soap as well, but I don’t think it’s essential.

how to thin wood glue with vinegar

In addition to using water to dilute wood glue, adding vinegar also seems to work.

There is no real ratio for this, but adding just a few drops of vinegar to wood glue would revive thickened wood glue.

I’ve heard about this technique before, but I have to admit that I haven’t tested it myself, so I can’t confirm this.

Logic would suggest starting with a few drops of vinegar, thoroughly mixing the glue, and observing what happens. If the glue remains too thick, you can add a few more drops of vinegar and mix it again. You can continue to do this until the wood glue has reached the right thickness.

How to Know When to Get Rid of Wood Glue

Although in many cases, thickened wood glue can be thinned out again, there may still be a situation where it is better to throw away the wood glue and buy new ones.

To know when it is no longer worth investing energy in diluting the wood glue, there are a few pointers that you can pay attention to. For more information I recommend you to check out my article How To Tell If Wood Glue Is Bad? 4 Tips To Avoid Disastrous Joints.

  • When the wood glue has become so thick that it is barely liquid.
  • When the color of the wood glue is no longer white, but rather orange, the glue has become too old, and it is better to throw it away.
  • If wood glue becomes lumpy, it has become unusable.
  • When the wood glue is stringy when spreading.
  • When a foam or sheet has formed on top of the glue.
  • It looks separated, like oil sitting on top of a solid.
  • It does not adhere to the wood at all when applied.

In some situations, you won’t notice any of the above until you’re already spreading the glue. In that case, it is better to remove the glue and start again with new glue. In my article How to Remove Wood Glue (6 Situations with Easy Solutions) you will learn how to do this in a good and safe way.

What if you have to throw away thickened wood glue?

In that instance, the first piece of advice is to throw it in the appropriate trash can. We must protect our environment, which is why it is critical that thickened wood glue that can no longer be thinned finds its way to the suitable recycling facility.

A second suggestion is to get new wood glue as soon as possible. It’s impossible to imagine a workshop without wood glue.

The different Titebond wood glues are PVA wood glues that I can suggest to you and that many pros also use.

Select the appropriate wood glue for the sort of connection you’re making. To assist you, I’ve created a list of which glues you may use for specific tasks.

The Titebond original (red) can be used for all interior bonding.
The Titebond premium (blue) has a fast drying time and can be used for bonding in damp areas.
The Titebond Ultimate (green) is good for bonding outdoors, and can also be used for items that come into contact with food.

How to thin wood glue – conclusion

Never throw away thickened wood glue. In most cases, you can easily dilute wood glue with water, rubbing alcohol, or vinegar. Once the glue has thinned, you can use it normally again without fear of losing the bonding strength and effectiveness of the wood glue.

Keep in mind that you should only thin wood glue a small amount at a time. This ensures that your wood glue remains usable for a long time. Therefore, read carefully the tips that you can find with these four methods on how to thin wood glue in this article.

Now you know how to thin wood glue, you can go back to work. But wait! do you have all the knowledge to use wood glue properly? Before you go back to your workshop, it is recommended to read my article How to use wood glue first!

Frequently Asked Questions

How long does wood glue take to dry?

Depending on the kind of wood glue and environmental conditions, it usually takes about a day for wood glue to completely set. More info: How Long Does Wood Glue Take to Dry? 5 Tips You Should Know!

Can wood glue be used on metal or plastic surfaces?

Wood glue is specially formulated for bonding wood surfaces, and may not effectively adhere to other materials.

Is wood glue waterproof?

Various specialized types of wood glue, such as maritime and waterproof varieties, are created to provide water-resistant or waterproof qualities.

Can wood glue be stained or painted over?

Once it has dried, wood glue can be tinted or adorned with paint.

Can wood glue be used to fill gaps in wood?

Wood glue, when blended with sawdust or other wood fibers, can be used as a gap filling agent that forms a robust paste. Wood glue by itself will not fill gaps in wood.

Is wood glue toxic?

Taking safety precautions is paramount; store wood glues away from children and pets as they are non-toxic, but still harmful when mishandled.

How can I remove excess wood glue from a project?

One can eliminate excess glue before it congeals by wiping off with a damp cloth or sponge, or use sandpaper or a scraper to remove it after the adhesive has hardened.

How long does an opened bottle of wood glue last?

A bottle of wood glue, once opened, can remain usable for one up to two years if it is the right kind and stored in an airtight container.

Can wood glue be used for outdoor projects?

Wood glue specifically designed for outdoor use can be utilized to complete weather-proof projects.

How can I ensure a strong bond with wood glue?

For optimum binding with wood glue, ensure that the surfaces to be adhered are spotless and dry, spread the glue uniformly and sufficiently, and secure the pieces in place for several hours until the glue is wholly dried.

Is wood glue stronger than screws?

The strength of the bonding depends on the application and what kind of wood glue and screws are utilized. Usually, if given adequate time to set and harden, wood glue offers a more substantial bond than screws do. Yet, in several cases, screws provide an initial stronger grip and might be required for some projects or materials. See more in my article Is Wood Glue Stronger than Screws? An Unbelievable Showdown!

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