Choosing which wood to turn

 

The content below is summarised from a number of sources listed at the bottom as well as my own opinions.  This is awareness raising for people new to turning and if needed it is suggested you check out the links below as well as other sources to become comfortable with the issues yourself – this is one area where there are often different opinions.  

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Wood is by far the most common material turned on wood lathes. Other materials that are used include Corian, acrylic and resin

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Within woods there are important differences relating to:

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• Whether it is hardwood or softwood

• What particular species of wood it is

• The Sustainability of the wood source

• The Toxicity of the wood

• Whether it is Kiln dried, Air dried or Green

 

Hardwood or softwood?

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Hardwood comes from deciduous trees: those that lose their leaves annually.  Softwood comes from conifers, which usually remain evergreen. The trees from which hardwood is obtained tend to be slower growing, meaning the wood is usually denser

There are exceptions such as Balsawood which is technically a hardwood but is very soft and light

Dust from hardwoods tends to be more toxic and able to cause allergic reactions but all wood dust is hazardous

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There are lots and lots of choices and ones decision is a balance between cost, availability, toxicity, colour, grain, ease of turning, finishing options as well as ones attitude to sustainability issues

The following have been seen to be reliable woods for turning - Ash, Maple, Walnut, Sycamore. Cherry, Elm, Beech, any fruitwood (and others)

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Softwood is generally easily available, cheap and good to practice on but can be difficult to finish well

Species with interesting grain often lend themselves to plainer decoration whereas plainer wood types can be stained, painted or physically decorated to add interest.  Oak is often available as not many turners like it and one can find large blanks easier than other woods.  It has an open grain but like cherry and others it can check and crack easily

You can glue up thin pieces of different woods for interesting effects or use plywood.

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Sustainability

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Sustainable wood comes from sustainably managed forests. Stewards manage the forests to prevent damage to eco-systems, watersheds, wildlife and the trees themselves; taking long term rather than short term view.

Deciding what wood to use is a judgement call rather than objective decision. Generally fast growing trees like Pine or Fir are more sustainable.

It is a complex issue however and often related to the sustainability of the environment and economic impacts of the use of trees for lumber. Also detail can be important some wood thought to be sustainable can come from illegal logging operations but difficult to chase down this information for particular pieces

The EU has introduced a legal framework to protect trees and forests so wood sourced from the EU is a relatively safe choice.  Wood from Asia, Africa or South America often come with more concerns

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Toxicity

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Only a few woods are actually toxic however many do have the capacity to cause allergic reactions. Yew and Laburnum are well known not to be food safe.

Most poisonous wood substances are found in the bark, leaves, or sap of a given wood species.

Even with properly cured wood, there can still be residual amounts of sap, or fragments of bark, hanging around in your wood blank.  Take extra precautions if you are turning a project that leaves the bark on such as, a natural edged bowl or vase.

Turned items from Spalted wood can be beautiful but be aware that the spalting is actually fungus and can cause lung problems.  Look out for kiln dried spalted wood as that is safer.

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Check out the Wood Database link in the box on the left as it lists all common and many uncommon woods with their particular hazard levels.

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Items that are designed to be used with food need careful choices (eg Ash, Sycamore, Holly, Walnut, Mahogany, Beech) and also need Food Safe finishes.

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and to emphasise the point ..

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“The yew is similar to these other trees in general appearance . . . It is an ascertained fact that travellers’ vessels, made in Gaul of this wood, for the purpose of holding wine, have caused the death of those who used them.”

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Pliny the Elder – written in 77 AD

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Green wood (Fresh sawn or unseasoned)

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Greenwood can be kiln dried commercially, air dried or used green.  The rule-of-thumb for air-drying  is to allow one year of drying time per inch of wood thickness.

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Drying time for green wood can be speeded up by the following process:

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• Rough turning a bowl blank leaving a significant wall thickness

• Storing it in a closed container or in a plastic bag with or without wood shavings

• Replacing wood shavings every couple of weeks if used

• Check moisture level with a moisture meter or weigh the bowl every so often and wait until it reaches equilibrium.

• Finally the item can be remounted on the lathe to complete the turning - expect the bowl to have distorted somewhat.

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If green wood is to be stored for a period of time, the end grain can be sealed with molten paraffin wax or a paraffin wax emulsion. 

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If you are trained to listen out for the sound of chainsaws then this can be a very cheap way of finding wood for turning.  Some tree surgeons often see wood as waste and happy for you to carry it away.

Turning is easier than turning dried wood and can be an excellent way to practice techniques and shapes. It also blunts tools less. The high moisture content of unseasoned wood will cause finished pieces to warp as they dry - mainly because end grain loses moisture faster than side grain Some turners capitalise on expected warping to give interesting results although it often means you need to complete the piece in one go as once it starts warping it may not be possible to remount and finish later.  Splitting is also likely if green wood is dried too quickly

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When turning greenwood, the lathe, the tools and the turner can get quite wet and all will need drying at the end.

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Air dried

This is green cut timber that has been stickered (ie stored in piles with spacers to allow air to circulate) and left to dry naturally in the air. In the UK, air-dried timber is unlikely to have moisture content lower than about 15% and it is likely to be somewhat higher than this. If the item is intended to be used indoors it may be worth bringing it into the house for a few weeks to acclimatise it to the  house environment before turning it - you will have a far more stable finished piece

Be aware there may well be remaining fungal spores in air dried and particularly spalted wood that have not been killed off

With time and patience, this can be a cheap way of obtaining wood blanks

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Kiln dried

This is timber that has been artificially dried commercially. Its moisture content can be brought down lower than air-dried timber. It is an expensive way of obtaining wood and it can be harder and dustier to work