There are a number of challenges and rewards in working with Oak.
Understanding these challenges can save time, energy and money.
For centuries, the physical properties of Oak have made it a perfect choice for external use in construction and furniture. Oak is solid, hardwearing and lasts seemingly forever.
It is extraordinarily resistant to water damage and pests and needs little or no maintenance. However, the very same properties that make it such a desirable material can make it difficult to work with.
Understanding the physical makeup of the timber itself and which cuts are most appropriate pays dividends.
Use the Right Variety
Most British users will automatically opt for European Oak. After all, it is the most widely available type.
This is no accident, European Oak is easily procured and suited best to the British climate, particularly for external applications.
Many online articles on Oak woodworking by American authors reference White or Red Oak. While Red Oak has its own distinct look, it is far less durable.
Red Oak has more open grains. With this porous texture, it significantly lowers its water resistance. Thus making it unsuitable for any outdoor projects.
White Oak is more durable than Red Oak with a much straighter grain. It also resists water much like European Oak does. However, European Oak is still preferred when it comes to structural projects.
Understand Green vs. Dried Oak
As Oak timber dries, the moisture that keeps it relatively soft is lost. It then becomes harder and more challenging to work with.
So if you are planning to work extensively on the timber, Green Oak is probably the best choice.
Green Oak is cost effective and is the most environmentally friendly.
If used outdoors, Green Oak will change colour, silvering over time in response to the elements. As a result, the wood will need to be treated if you wish to retain the original colour.
Green Oak will also shrink over time. If it is used for cladding or flooring, this will need to be taken into account to avoid unsightly gaps.
For renovation projects where the existing timber is already aged, Air Dried or Kiln Dried Oak is a better choice. It will already have a ‘pre-aged’ look more consistent with the existing woodwork.
Due to the lower moisture content (20% – 30% for air dried, 8% – 10% for kiln dried) it will be harder and more difficult to work with.
Before drying, the timber will be cut to specific lengths, so finding larger sizes may be difficult, if not impossible.
Drying also takes time, so if supplies run out they can be difficult to replace without a considerable wait.
Fixtures and Fittings
Traditionally Oak structures have used tenon and mortise joints or wooden pegs. This was mainly due to the cost of metal components or a lack of availability, especially in rural locations.
For the modern user, there is no shortage of metal fastenings, but care must be taken in which is used. Iron based metals are best avoided as the tannins in the Oak can react with the iron.
This causes blue or black staining, commonly known as ‘tarring’. These stains can only be removed by bleaching agents such as oxalic acid.
In Green Oak the higher water content can cause iron to rust, weakening the joint.
Brass, aluminium or copper are far more suitable metal options, but while brass fittings complement the colour of oak, they can be prone to shearing.
If glues are used, care must be taken as water based glues can cause swelling and warping in dried oak as they transfer moisture back into the timber.
Keep Your Tools Sharp
With any hardwood and especially Oak, sharp tools are an absolute must.
The cells of the wood are packed tighter with few air spaces in between them. As a result, chisels and planes will have a far tougher time parting the grain without the sharpest edge.
Using force to drive in a dull edge will result in splitting rather than cutting, damaging the wood beyond repair.
Planing without a sharp edge will lead to the plane skating over the surface rather than shaving it.
Attempting to adjust depth and push harder will only make the job harder.
Oak is also susceptible to burning from the friction of blunt power tool attachments. Not only will this leave burn marks requiring intensive sanding to remove, it can damage blades and bits.
Finally, when working with Green Oak, all tools should be cleaned and dried afterwards. The moisture and tannins can cause corrosion.
Woodworking Techniques
Where possible, use quarter sawn timber if you will be planing it yourself.
With Oak this is not difficult as the size of the original tree means much of the timber derived will be quarter sawn. The wider edges will be cut across the radial plane, that is, across the growth rings. The weaker bonds along the radial plane mean far less effort is needed during planning.
Planing the narrow edges will be harder, but the smaller width means less work is needed. Timber merchants are often able to plane for you before purchase, if required.
If planing the ends of boards is necessary, wetting the ends will allow the timber to absorb moisture and soften slightly.
Alcohol is often recommended for this, but it can evaporate before the work is finished. Apply water or mineral spirits liberally and leave for a couple of minutes to absorb and soften the wood. Linseed oil works even better if it is available.
Cutting mortises or dovetails can be incredibly time consuming if only using a chisel on Oak.
Try using a coping or turning saw to cut to the baseline of the gap between dovetails, then use a sharp chisel to tidy up and finish the gap.
To cut out mortises, use a brace and bit or power drill to bore out most of the waste. Then finish and tidy up with a chisel.
Oak has particularly heavy graining and this can cause problems when routing, splitting or chipping at the ends if it is worked too aggressively.
Rather than attempting to rout the surface in one pass, use two or three passes with less force. This should result in a neater, more consistent finish.
Hardwoods Group consists a team of experienced craftsmen ready to answer any questions you have.
