What are the major differences between the various timber types?

We have included a few statistical tables for comparison but in general timber is normally grouped in 2 ways.


Firstly Hardwoods and Softwoods

And secondly in Fresh or Seasoned/Kiln Dried timber.

Following these 2 common groupings all timber is also categorised for durability, hardness and weight. Of this set only the durability is of concern to us.
With such a range its often confusing to work out what timber you want your furniture to be built from.
All out timber is durable and suitable for outdoors – some are just better than other so here are the simplified characteristics.

Climatic Durability Statistics
Timber Type Category Durability
Ironbark/Greygum sleepers Fresh Excellent 10/10
Blackbutt F27 Harwood Seasoned Excellent 10/10
Cypress pine Fresh Excellent 10/10
Treated pine sleepers H4 Fresh Excellent 9/10
Recycled railway sleepers Seasoned Very good 8/10
Red gum sleepers Fresh Very good 8/10
Treated Pine F7 Kiln dried H3 Seasoned Very good 7/10
Merbau Seasoned Very good 7/10
Vic Ash and Tas Oak Seasoned Poor 2/10
Radiata Pine Seasoned Poor 1/10

Weight Statistics
Timber Type Weight per cubic meter
Ironbark/Greygum sleepers 1105 kg dry, 1270 kg wet
Blackbutt F27 Hardwood 950 kg
Cypress pine 500 kg
Treated pine sleepers H4 700-1100 kg (dryish-wet)
Recycled railway sleepers 950 kg

The stability of the timber - resistance to cracking twisting shrinking
Timber Type Category Stability
Blackbutt F27 Hardwood Seasoned Excellent 10/10
Merbau Seasoned Excellent 10/10
Vic Ash and Tas Oak Seasoned Very good 9/10
Recycled railway sleepers Seasoned Excellent 9/10
Treated Pine F7 Kiln dried Seasoned Very good 8/10
Radiata Pine Seasoned Very good 8/10
Cypress pine sleepers Fresh Below average 4/10
Treated pine sleepers Fresh Below average 3/10
Ironbark/Greygum sleepers Fresh Poor 2/10
Red gum sleepers Fresh Poor 2/10

 

Summary Analysis of Timber Characteristics

Seasoned Blackbutt: F27 Hardwood : Extremely durable, stable and clean grain and texture.
Blackbutt is fully seasoned and comes in a 45mm thickness making it ideal for most furniture application but it comes at a significant cost. It is extremely durable, hard and clean with absolutely minimal shrinkage or cracking making it an ideal timber for dining tables painting or oiling. For a clean look it’s the number 1 choice.

Fresh New Ironbark Garden Sleepers : Extremely durable and rustic.
This is a very dense hardwood sourced from Queensland mills. It was cut down weeks or months ago and is still full of moisture internally. It will dry out over a season or two during which time it will shrink and cracks to some degree. Gaps will appear between boards and cracks on the surface and ends.


Treated Pine F7 Kiln Dried : A very durable structural timber used extensively in the construction industry.
The surface is lightly reeded and the timber is relatively dry so the is minimal shrinkage or cracking that will appear once its made into furniture. It is a softwood and easily marked but it also have the ability to be stained to a multitude of colours. Almost all stains are based on applying to treated pine timber. Note that F7 treated pine is only 45mm thick – the thicker garden sleepers have a totally different characteristic.

Treated Pine H4 Garden Sleepers : 75 and 100mm thick) Extremely rustic and durable.
This timber has most likely just been treated and is wet. It will naturally dry out over a season but the drying process will cause significant shrinkage, some cracking and some degree of twisting. It is very economical but be prepared for this furniture to change shape.

Cypress Pine : A very knotty but durable softwood.
Similar to ironbark it was milled recently and will need to go through a drying process over a season or so during which time some shrinkage and cracking will appear.

Recycled Railway Sleepers : Extremely rustic and very durable.
Most are made from either red gum or ironbark and are characterised by spike holes and minor defects. These are thick and work well with garden settings.

Red Gum Sleepers : Extremely rustic while being durable.
With government restrictions on harvesting red gum there is a lot of poor quality timber emerging and we have almost stopped using it due to the poor quality factors. It will shrink considerably and is prone to twisting as well.

Merbau : Is an imported seasoned hardwood and there are some local similar equivalents.
It is normally used for decking and lining but thicker (42mm ) planks are sometime available for furniture. It is clean, red and will leach out red dye for a while but it is a seasoned stable hardwood.

Vic Ash or Tasmanian Oak : A seasoned semi hardwood. Clean but not suitable for outdoors
A local hardwood with a light tone used in the construction industry. It might be OK for sheltered areas but should not be in contact with the ground or moisture.

Radiata Pine : A very soft wood with a smooth finish characterised by knots.

It is definitely an indoor timber. It is light and stable but very soft. It marks easily but does not shrink or crack.