How to Dry Wood Fast: Use a Solar Kiln!

If you’re trying to up your woodworking game, then consider preparing your lumber rather than purchasing them from retailers like some lumber-purchasing maniac. It’s a lot more satisfying – and economic – to saw and dry lumber in-house.

What is Wood Drying?

Wood drying or seasoning is exactly what it sounds like – you dry the wood until most, if not all, of the moisture, has evaporated. Drying your piece of lumber is a must-do step. Since virgin or green lumber contain moisture straight from the trunk, the size of the stock will vary slightly after it has dried. If you build furniture using green timber, the finished product could warp, split, or crack as it dries out. It’s also important that you season lumber used for fireplaces as droplets of moisture could prevent the log from holding a flame.



Methods of Drying Wood

There are four ways to dry wood in preparation for further use. These are air-drying, kiln-drying, microwave-drying, and using a solar kiln.

Air-Drying

The classical way to get your lumber as dry as a bone is by letting the air do the work. This is done by stacking the logs or plants outdoors and on raised pallets to prevent them from making contact with moist dirt and grass. You can wrap the stack in a plastic sheet or place them under an overhead canopy to prevent rain from seeping into the logs. Eventually, the logs will be done-dry and ready for further processing. Keep in mind that air-drying your logs can take up to 9 months, so it’s not the most time-efficient method.

Kiln-Drying

Commercial companies use a kiln to season their lumber. A kiln quickens the drying process by removing excess moisture by way of introducing heat from an external source. It only takes about 2 to 7 days to complete depending on the type of wood you’re drying.

Kiln-drying can be further divided into two categories – progressive and compartmental. Progressive kiln-drying is similar to an assembly line belt that passes through an oven. As it reaches the end, the lumber should be moisture-free. Compartmental kiln-drying involves leaving the bundle of logs in a huge oven-building. As you can probably guess, kiln-drying is an expensive process that only huge companies can afford.

Microwave-Drying

In this drying process, pulsed energy is shot directly into the logs to force moisture out and reducing the risk of degradation during the process. This is by far the quickest method of drying lumber and is most appropriate for veneer, chips, and composite materials. Once again, the downside of this method is the initial investment cost. Saving time can mean having to mortgage your home.

Solar Kiln

If you’re looking to reduce the amount of time needed to dry logs without having to strike a deal with the financial devil, then a solar kiln may be the solution for you.

This method has the benefits of both the speed of kiln-drying and the low cost of air-drying. You can even construct your solar kiln if you have the time and materials.

This method harnesses the power of the sun – like in air-drying – and keeps heat inside – like a greenhouse. A fan or similar device can be used to circulate the air inside of a metal/wooden/plastic construction to evenly dry out the log bundle.

However, know that you’re not going to be able to dry out your logs in a week thoroughly. It may take twice as long or even longer, but at least you won’t be waiting around for nine months to begin your woodworking project. Plus it’s extremely affordable to make, use, and maintain.

Solar Kiln Construction

Building your own solar kiln is a piece of cake. In addition, you won’t need to move money around or make a payment plan to construct one since it can be made of simple, easily purchased materials.

1. To begin construction, prepare a small piece of land. Dig away any grass or vegetation that is growing on that land to prevent moisture-building from impairing the drying process.

2. Next, build a frame using 2x4s around the empty land. The dimension of the frame is up to you – it can be as small or as large as you like. Just keep in mind that you’ll want the frame to be large enough to house all the lumber you want to be dried in one session.

3. After the frame is constructed, cover the exposed dirt using cardboard. The cardboard will prevent any growing plants from poking through the upper layer of plastic that we’re going to lie on top of the cardboard. The plastic should be thick enough not to let moisture seep through.

4. Next, place a few boards on top of the plastic. These boards will raise the green lumber, so they don’t touch the plastic. This also helps air circular not just on the top and sides of the lumber but also under it.

5. The next step is to wrap the entire frame, except for the roof section, in black plastic. The plastic will prevent rain and moisture from seeping in through the sides of the construction, and a darker color will do a better job at retaining internal heat.

6. Now you’re ready to place timber inside of the kiln. Make sure that there aren’t any sharp edges that can poke through the plastic. Also, you need to ensure that the lumber isn’t touching any of the sides or the plastic floor. The logs should rest comfortably on the support boards.

7. The final step is to add a clear corrugated plastic roof on top of the solar kiln. It serves two purposes – first, rain won’t fall into the construction and dampen the environment within; and second, these panels will allow sunlight and heat to enter the kiln.

Solar Kiln Tips

Here are a few pointers on how you can build an effective solar kiln.
1. Have the kiln facing toward the direction where it’ll absorb the most sunlight. More sunlight means a quicker, more effective drying process.

2. Set the plastic roof at an angle. The safest angle to go with is 45°, but if you want to get technical, the angle of the roof should be set to your location’s latitude north of the equator. This will give the solar kiln more exposure to sunlight during non-wintry months.

3. Maintain the kiln as necessary. The solar kiln we described above won’t hold forever, and some components of the construction may need periodic replacing or upgrading. Feel free to modify the design as you see fit.