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How to dry wood? What are the best methods?

In this blog post, I will discuss with you 10 different simple methods to dry wood.

What are the best methods to dry wood?

The 10 best methods to dry wood are:

  1. Kiln-drying
  2. air-drying
  3. chemical or salt seasoning
  4. solar kiln
  5. dehumidification kiln
  6. drying in a microwave oven or conventional oven
  7. electrical seasoning
  8. boiling or steam seasoning
  9. water seasoning
  10. vacuum kilns.
Øyvind Holmstad – CC BY-SA 3.0, Link

What is the easiest method to dry wood?

● Air-drying

The easiest method to dry wood is to use air-drying. For air-drying you only need to stack the wood and let it dry outside. It is a cheap method, but it takes a really long time, and it is difficult to reach a low moisture content. It is also not usable in a high humidity location.

● Kiln-drying

Kiln-drying is the most used method to dry wood. It is fast, can be replicated due to a controllable environment, can be used in a high humidity location, and can be used to reach a low moisture content. Kiln drying is used in most commercial wood shops, but the drawback is that it is a relatively expensive method and you need some equipment for it. There are several methods to kiln dry, some of them can also be used at home.

What are the cheapest methods to dry wood?

● Air-Drying:

Air-drying wood is one of the cheapest methods to dry wood and is easy to do. It only takes a long time and it is difficult to reach a low moisture content. You will need the following things to air-dry wood:

  • Chainsaw or wood splitter
  • Goggles
  • Wood pallets
  • Tarp

You can follow this simple step by step guide to air-dry wood:

  • Step 1: You will need at least six months to dry wood, so make sure that you start the process in the spring season so that it is finished before the snow begins to fall again.
  • Step 2: Put on your safety gear or personal protective equipment and use your chainsaw to split the wood into small pieces.
  • Step 3: Find the direction of the wind.
  • Step 4: Choose a slightly sloppy place to allow the rainwater to drain in case of heavy rainfall. Put a tarp on the ground to keep the moisture out.
  • Step 5: Pile up the wood and make sure that the piles are not more than about three to four feet (0.91–1.22 m) tall.

2. Chemical or salt seasoning:

Chemical or salt seasoning is a method of drying wood which involves the submersion of wood in a solution of urea, sodium nitrate, all of which act as dehydrating agents. Then the wood is air-dried. The preferred concentrations of the hygroscopic organic chemical in the seasoning solutions vary from about twenty-five to seventy-five percent by weight depending upon the solubility of the particular chemical used, the particular wood to be seasoned, and the conditions of temperature and humidity prevailing during the kiln drying or salt seasoning procedure.

The preferred amounts of water-soluble chlorophenol required with such mixtures vary between 0.25 and five percent by weight of the hygroscopic chemical used. The exact amount used depends on the particular wood to be seasoned and the climatic conditions under which the treating and seasoning operations are carried out. Somewhat higher or lower concentrations may be used, depending on whether the conditions are more or less favorable for mold growth.

In certain instances, for example, when molasses or invert sugar are used as the seasoning agent, small amounts of alkali are added to the seasoning solutions to reduce the tendency of the phenolate to dissociate and precipitate free phenol.

3. Solar kiln:

It is a kind of greenhouse with a high-temperature fan and either vent or a condensing system. Solar kilns are slower and variable due to the weather. It is one of the lowest cost methods to dry the wood.

The roof angle is really important while building a solar kiln. You must, first of all, determine the latitude of the place where you are planning to build a solar kiln to dry your wood; then you must use that latitude number, plus or minus five degrees, for the solar kiln roof’s pitch. In Minnesota, for example, the latitude is about forty-five degrees north, so you must mount the solar panel at a forty-five-degree angle.

A solar kiln needs minimum effort and time in its adjustment. You can literally set it and forget it. It is almost impossible to dry 4×4 wood too quickly.

Even so, most hardwoods can be dried within just 6 weeks during the peak summer season. A load of basswood will take only 4 weeks. A conventional kiln dries the wood continuously and has to be monitored closely to prevent exceeding the safe drying rate for that species.

A solar kiln is cyclical. During the daytime, the solar kiln heats up and the fan comes on to circulate hot air through the stack of wood placed inside it. Moisture is drawn from the wood into the air and is vented outside through the vents or leaks out naturally through the solar kiln’s joints and seams.

At night, the cooling cycle starts. The temperature falls, the fan shuts down and the moist air condenses. The surface of the wood gets wet and cool, relieving any drying stresses that built up during the day time.

A solar kiln is like having an automatic conditioning cycle built-in.

4. Dehumidification kiln:

These kilns traditionally operate from one hundred degrees Fahrenheit to one hundred and sixty degrees Fahrenheit and use about half the energy and a minimum investment of a conventional kiln. It is an unvented system (closed-loop) or a partially vented system that uses a heat pump to condense moisture from the wood using the cold side of the refrigeration process (evaporator). The heat thus gathered from the wood is sent to the hot side of the refrigeration process (condenser) to re-heat the air and return this drier and warmer air inside the kiln.

Fans are used to blow the air through the piles of wood as in a normal kiln.

What are the fastest methods to dry wood?

1. Drying in a microwave:

To dry wood in a microwave is easy, but can only be used for small pieces of wood. Make sure you have a fire extinguisher, some large tongs or thick oven mitts, and something to put the wood on to cool down.

● Step 1: Put the wood in the microwave

Put the wood in the microwave and make sure that it fits, and if your microwave uses a rotating plate that it can still rotate. You can stack similar wood pieces that have an equal moisture level. If you are not certain about the moisture level using a moisture meter. Also, add some paper towels to suck up the moisture released from the wood.

● Step 2: Set the microwave to its lowest setting

When you start the drying process use the microwave in its lowest power setting. Sometimes this setting is called defrost.

● Step 3: Let the microwave run for 30 seconds

Turn the microwave on for 30 seconds and make sure that there is no smoke or fire visible. The wood can get very hot inside and can catch fire, in that case, turn of the microwave immediately.

After the 30 seconds let it cool down a little bit and remove the wood from the oven. Use oven gloves as it can get very hot.

● Step 4: Check the moisture level and repeat the process

Use a moisture meter to check the moisture level. Repeat the process until you have reached the needed moisture level. Make sure you turn the wood every time so parts that where touching can now release the moisture

● Step 5: Let the wood cool down

When you have reached the needed moisture level let the wood cool down, this can take up to an hour.

1. Drying in a conventional oven:

To dry wood in a conventional oven is also easy, and similar to a microwave can only be used for smaller pieces of wood. Make sure that you prepare yourself well and do not forget to have a fire extinguisher, some large tongs or thick oven mitts, and something to put the wood on to cool down.

● Step 1: Prepare the Oven

Check that your wood fits in the oven, and make sure you only combine similar wood types with the same moisture level. You can use a moisture meter to check this. Use open racks in the oven if you have them, with closed racks you have to turn the wood more often.

Preheat the oven to somewhere between 200 and 225 degrees F (95 to 110 degrees Celsius). If you have a hot air oven use that setting.

● Step 2: Add the wood to the oven

Try to fit the wood in the oven so no two pieces or touching and make sure that they can not fall through the spaces in the rack. Add a small tray of water at the bottom in an oven resistant jar, this will help to equalize the moisture content in the wood.

● Step 3: Let the wood dry for an hour

Depending on the size of the wood and the needed moisture level it will take about an hour. Thick wood will take longer, smaller pieces that have a lower moisture level will take less time. Check every 10 minutes to see that all is well.

● Step 4: Check the moisture level

Take some pieces out of the oven, and let it cool down a little bit. Don’t forget to use your oven mitts as the wood will be very hot. Check the moisture level of the wood, and if you have not reached the desired level put it back and let it bake in the oven for an additional 10 min. Repeat this process until you reached the moisture level you want. Use a moisture meter if you have one.

● Step 5: Let the wood cool

Remove all the wood from the oven and let it cool down each piece of wood using oven mitts.

Place in a dry, protected space to cool down. This can take an hour. Recheck the moisture content

2. Electrical seasoning:

Electrical seasoning is the process of running an electric current through the wood causing heat to build up drying the wood. This method of drying wood is expensive but it is one of the fastest methods to dry wood. You get uniform quality wood after drying it through electrical seasoning.

3. Boiling or steam seasoning:

Submersion of the wood in boiling water or the application of steam speeds up the drying of wood. This method of drying wood is one of the most expensive methods to use, but it causes less shrinkage, reduces the strength and elasticity of the wood.

4. Water seasoning:

Water seasoning is one of the fastest methods to dry wood. It involves the immersion of wood in the running water quickly to remove its sap and then the wood can be oven-dried or kiln-dried. This method of drying the wood reduces the elasticity and durability of the wood and also makes it brittle.

5. Vacuum kilns:

The use of these kilns is one of the fastest methods to dry wood. It is also one of the most efficient with energy usage. At a vacuum kiln, water boils at a lower temperature.

In addition to speed, a vacuum kiln can also produce an improved quality in the wood. Low ambient pressure does lower the boiling point of water but the amount of energy required to change the liquid to vapor is the same. Savings come from not being required to heat a huge building and not being required to vent the heat while lowering humidity.

Since all free water can be removed under one hundred and fifteen degrees Fahrenheit, the quality of the wood is improved. While conventional drying uses warm, dry air to skim the water off the surface, vacuum kilns can boil water from within the wood. This enables a good vacuum kiln to dry very thick wood very quickly.

It is possible to dry 12/4 Red Oak fresh off the saw to seven percent in only as little as eleven days. Since wood is dried with a vapor gradient – vapor pressure to ambient pressure – humidity can be kept very high. Because of this, a good vacuum kiln can dry four and a half-inch thick White Oak fresh off the saw to eight percent in less than 1 month.

This achievement was thought to be impossible previously.