What is Pound Balsa?

What is Contest 4 to 6 Pound Balsa?
Contest Balsa is nothing more than balsa that should fall within 4 to 6 pounds measured by density in pounds per cubic foot.
But all you really need to do is to think about the application area of your model, especially when you enlarge plans or build larger aircraft. An investment in a nice electronic gram scale will be a big help. The chart below is a great reference for wing sheeting which can be applied to other areas of your model building. If the hobby store doesn't mind, bring your gram scale with you when you purchase balsa for your next project so you can build lighter, larger and stronger model aircraft.
Balsa Grains
A-Grain: Balsa sheet has long fibers that show up as grain lines. Its very flexible across the gdjlhqgnvz sheet and bends around curves easily. Watch-out it warps easily.
B-Grain: Balsa sheet has some of the qualities of both A & B grain. Grain lines are shorter the A and feels stiffer across the sheet. It is a general purpose selection and can be used for many different jobs
C-Grain: Balsa sheet has a mottled appearance. It is very stiff across the sheet and spits easily. Great for wing ribs and light formers. When used properly, it will help you build a light yet very strong model. Four to Six pound balsa stock is commonly called "Contest Balsa"
article resource: http://www.balsafactory.com/ .