How To Harden Wood

How to Harden Wood


Working with wood lets you admire its strengths and work on its weaknesses. Some varieties of wood are hard while some are weak. Others can resist moisture while some can suck up water like a sponge.

Because you want strong and resilient wood for building and construction, you need strong and hard wood. This guide will show you how to harden wood which you can do even at home.

Hardening wood basics

Wood is a versatile material. It can work with the elements to give you strong and reliable building material for furniture making and for constructing homes and structures. These are the steps on how to harden wood using the most popular fire hardening method.

Things that you will need

  • Wood you will be working on
  • Charcoal
  • Stones

The fire-hardening method

The fire-hardening method is the most common technique to harden a piece of wood. And while this is called fire hardening, it is not fire that hardens the piece of wood but heat.

The heat coming from the fire will remove the moisture from the piece of wood like in the kiln-drying method. Because of removing moisture, the wood grain will tighten up and cause the piece to harden up.

And although this is a very popular method, it is extremely tedious and you need to be very careful not to burn or overly dry the wood and avoid getting hurt as well. If you are not careful, high heat can also damage the quality of the wood you are working on.

If you put a piece of wood into the fire and leave it even for a few minutes, it could catch fire and burn to ashes.

The key to using the fire hardening method is that you must exercise patience. You don’t need to hurry the hardening process because doing so can lead to burning and ruining your project.

You might even have to try several times before you can completely master this hardening technique. This technique was actually used to make wooden tools and weapons harder such as making arrows and spears.

Here are the steps to harden wood with fire:

1) Prepare a fire pit

Prepare A Fire Pit


Not everyone has a fire pit but if you are serious at becoming a good woodworker then it would probably pay off if you had your own at home. A fire pit will be useful for other projects as well other than hardening wood.

To make your own pit, you can dig a hole about half a feet deep and two feet across in your yard. Place rocks surrounding the pit and then some rocks and charcoal in the middle.

2) Light up the charcoal

Light Up The Charcoal


Now it’s time to light up the charcoal in your pit. You can use butane to light up the pieces faster and by the time you have a fire, tend it and slowly make the flames bigger and warmer.

Continue adding more charcoal to the fire until it stabilizes. The best flame for hardening wood is about 6 inches high and should have a blue center. This means that the fire is very hot and very warm.

3) Time to harden the wood

Time To Harden The Wood

When you have a steady blue flame, hold the piece of wood over the flames for a few minutes. Do not place the piece of wood too close to the flame otherwise, this could only burn. There should be at least a gap of 3 inches between the flame and the piece of wood.

Now that you are in the process of hardening wood, watch out for burning. When an area gets a little bit warmer turn that piece of wood around. Use a pair of tongs to hold the wood. Change the sides of the wood constantly to prevent overheating and burning.

4) Check the condition of the wood

Check The Condition Of The Wood

You are aiming for hard wood but you must also check for early signs of burning. So stop once in a while to check the condition of the piece of wood. If the surface of the piece of wood looks dry then all the sap and moisture has been removed.

5) Cool wood down

Cool Wood Down


You now have a piece of hardened wood. Take it out of the fire pit and store it in a cool and dry place.


Hardening wood is a way to make the wood stronger and ready for construction or for use in building and furniture making. You can make use of the fire hardening method which is a very common technique but no doubt quite intensive because you need to keep track of your wood at all times.