Fresh Sawn, Air Dried and Kiln Dried

When a tree is initially felled, it is classified as fresh sawn or green – it contains a high moisture content.  This moisture will dry out over time when the timber is used under cover or inside buildings, however when it is purchased fresh sawn and used straight away it will start to crack and split once it has been moved to a drier environment.  This is often seen as way of making the timber look original and having more character.

Air dried timber has been stored outside or in a well ventilated shed – this gives the timber a more acceptable lower moisture content which is required for kiln drying.

Kiln drying is where the timber is placed in large kilns set at a constant temperature and slowly dried to a moisture content of aprox between 7 – 12%.  This makes the timber stable enough to use in furniture, flooring and joinery without excessive amounts of movement or splitting in the timber when it is in a dry environment.  All wood flooring is kiln dried.

Timber is sold in many formats depending on the quantities.

After logging, timber is usually sold in boules – where the log has been cut through and through into set thickness planks but still kept in the order from the log – this is an ideal way to purchase oak when the grain and colour matching are important.  The timber comes wany edge in boules.

Rough sawn timber has been cut into set thicknesses and usually has the waney edge cut off (however this can be kept on depending on the supplier) The most popular thicknesses are 27mm (1″) and 54mm (2″) and this timber is commonly used for basic furniture making eg shelving, steps etc.

Planed oak has a smooth finish.  The rough sawn timber has been planed down to give a finished appearance enabling easy usage even for DIY furniture making.

Species of Oak

There are many species of oak however the major two are American White oak and European Oak.  Alot of people ask whether there is any difference between French, German and English oak, however there is such little difference most joinery manufacturers often incorporate all types in the same piece of work – even experts in oak have difficulty in spotting the difference.  As a rule, we do not supply English oak due to ecological factors, however it can be sourced if necessary.

American White oak and European oak do have more differences than the European oaks.  American White oak isusually supplied square edged whereas European oak is mostly supplied in boules or waney edge.  Due to this the European Oak is available in larger and wider boards.  The colour in both types of oak can vary depending on the region and the soil type, but American White oak is heavier than European oak.  The main difference is when the oak has been finished.  The European oak has a much warmer honey glow appearance whereas the American White oak can have a duller, blander finish.

All types of oak come in different grades which include rustic or character grade, Rustic A or classic grading, first grade and prime grade.  Various manufacturers have different gradings so there is no set rule or specification for each grading.