Balsa grain.

[Papa]

I thought we should have this information readily available.


The attachments are a diagram of where each cut comes from the log and examples of the three cuts or grain.



'A-grain' or also known as a Tangent cut. This cut of balsa has a long grain, smooth creamy appearance and is very flexible but lacks stiffness. This cut is called a tangent cut because the sheets of balsa are sliced off at tangents to the growth rings.
Ideal for: sheet covering on curved fuselages. Wing leading edges (D-boxing etc). forming tubes (motor holders) and flexible spars.

'C-grain' also known as a Quarter grain. This cut of balsa has shorter grains, mottled in appearance (typically) it is quite stiff but subsequently brittle and prone to splitting along the length of the sheet. The sheets of balsa are cut at a perpendicular angle to the growth rings. Of all the cuts this is regarded as the most aesthetically beautiful.
Ideal for: Sheet balsa wings and tails, flat fuselage sides, wing ribs, fuselage formers, and wing trailing edges.

B-grain' also known as Random or Mixed grain cut. These sheets vary a lot in properties, often a single sheet will vary from A to C grain across its width. If possible, avoid buying sheets that change grain type across the surface, ie they appear to be C grain on one side and A on the other edge these will cause warping issues.
You will find that most LHS stock tends to be in the 'B-grain' category simply because from a given tree there is only going to be a limited number of quality A and C selections. This cut of wood is useful as a general purpose selection, if you don't have specifically a Tangent or Quarter grain stock selection to use for the job at hand, then the random cut will suffice.