Plywood is a natural timber material, which means humans have no control over its characteristics. Part of the beauty of plywood are these imperfections that give the material individuality and personality.
Here are some notes on the adorable little personality traits (not defects) you will find in Plywood.
The Butterfly Patch
These little patches are a snug and flush replacement for naturally occurring knots in the timber. It may have been from a branch growing in that spot or a tear in the thin and fragile veneer.
Sometimes you can be lucky and not have any on your sheet. Other times there might be 5 or 6 on one face.
The only time you are guaranteed a butterfly-free sheet is if you purchase A-Grade Birch Plywood, even then you may want to hand pick each sheet. We use B Grade Birch Plywood so that our furniture is affordable for our customers.
Plywood is made by laying one sheet of veneer on top of another. Butterfly patches are not applied during this process which means that a void from a knot on one layer of veneer will remain as a void. The ply is still strong because these are only small voids and across the size of the board the layer is supported on either side.
It is not possible to see these voids until you are cutting into your sheet, making it impossible to elude. Very often these will land along the edge of your cut.
We never fill these voids as they are a characteristic of plywood. Some bespoke plywood makers will lay their own sheets using A grade veneers to avoid these voids at a significant cost.
Our plywood comes from Finland or Russia depending on the yield and the season. If Finland have harvested all their Birch Plywood, then buyers go to the forestry in Russia while Finland’s Birch trees are coming to maturity. This change in geographic location is enough to produce slightly different tones in the timber, as well as grain density and even number of layers within a board of ply that make up its final thickness.
You may notice your Birch Plywood furniture is becoming darker over several years. This can be due to UV exposure levels or daily use as well as the age of the finish. Remember that UV exposure happens even when not in direct sunlight!
This can also affect certain parts of your piece, say if you left a stack of books on a plywood benchtop for a few months, you might be left with a book shaped mark of unexposed wood.
Plywood at So Watt
Our Plywood furniture is finished with Osmo wood wax (an industry favourite). Osmo wood wax is a wax and oil combination with a slight white pigment to help prevent yellowing of the timber during the finishing phase, keeping it as true as possible to the original tone.
Because Osmo has a large amount of oil, it is susceptible to a phenomenon called ‘dark yellowing’.
This article provides a comprehensive explanation: http://www.justpaint.org/what-is-dark-yellowing/