Pine vs Hardwood
For clarity, this article was written from a point of view of timber used in Northern Europe and North America. When referring to hardwood, it refers to tropical / exotic hardwoods, rather than indigenous hardwoods like oak and rosewood.
So many people ask us 'which timber works best with linseed paint'? There has been an enormous influx of exotic (or tropical) hardwoods over the last 3-4 decades and the jury is out on whether this has made any difference to the lifetime of windows and doors. The often-heard argument in favour of timber variations such as Padauk, Accoya, Mahogany and Teak is that they last longer than indigenous timbers such as Douglas Fir.
The problem of rotting timber is caused by non-wicking or non-breathable products which are applied to timber. If moisture cannot wick out and timber remains saturated, it will eventually rot. This process just takes longer in exotic hardwoods. I have seen hundreds of windows in historic buildings where the timber was actually in pretty good nick but the paint looked cracked and peeled.
This is a medieval cabin in Kulturen open-air museum in Lund, Sweden. The pine has only ever been treated with linseed tar and linseed oil. Imgage (c) Kulturen.
Imgage (c) Kulturen.
FSC regulations have meant that we no longer use slow-grown pine, however this is irrelevant. As long as the new pine has been stored for at least a year (and preferably kiln-dried), and is treated with linseed oil and linseed paint, the moisture will be able to wick out. This also means that timber should NEVER be tanalised or treated with non-permeable products.
I recognised that for decorative purposes, tropical hardwoods can offer something pine doesn't. But why are we shipping tropical hardwoods 6,000 miles across the globe when the intention is to paint it anyway?
Airmiles, embodied energy, deforestation which will take many decades to regrow... the arguments against not using tropical hardwoods is endless. And the 'alternative' is just as good if not better.
Recently, we tested our linseed paint on Padauk, Douglas Fir and a piece of original pine glazing bar for a conservatory for which an architects practice were deliberating on which timber to use.
I carried out the following work on the samples they provided:
0. (on glazing bar sample only, stripped the existing paint off using the Speedheater Cobra)
1. Sanded the samples down using 100 sandpaper. This is essential as it helps to open up the surface for the linseed oil.
3. Sanded lightly (200-240)
4. Applied 2nd coat of paint (colour Restoration White), undiluted, straight from the tin
5. Sanded lightly (200-240)
6. Applied 3rd coat of paint (colour Restoration White), undiluted, straight from the tin
These are the finished samples: