Many defects encountered in the lumber you buy for building furniture or home improvement are merely cosmetic, not structural. In fact, for some purposes, defects are valued. Take knotty pine for instance, which was a trendy wall paneling choice for many years. Another good example is wood with burls.
Other defects, other than knots, include bark pockets, splitting, checking, bug damage, warping, and more. Many of these can give your projects character. For example, burls are highly cherished. Yes, you can end up paying a premium for a cosmetic defect.
In most cases, you will only be concerned with staying away from checking, warping, and splitting, as these kind of defects make joinery difficult.
National Hardwood Lumber Association Grading
The NHLA has been in the business of grading hardwood for over 100 years. Keep in mind that their grading is more focused on yield, not looks. But if you shop with their guidelines in mind, you can save some serious money.
Here are how they see things from the best (most expensive) to the worst (most frugal):
FAS (First and Seconds). This stock must be at a minimum 6 X 8. The most defective face must be 83 1/3% defect-free.
FAS 1F or F1F. This is the same as FAS, except that it is graded from a basis of the best side of the board. This is a good choice when you are only concerned with what one side looks like (and isnt this usually the case?).
#1 Common. Similar to FAS, this is graded from the most defective face. The difference is that the minimum board size is reduced to 3 X 4. Another big money-saver for appropriately sized projects.
# 2A Common. This simply reduces the size to 3 X 2. You can see where we are going here. On smaller woodworking projects, the opportunity for savings are greater.
Shopping for Lumber is Not Grocery Shopping
Unlike packaged consumer goods at the grocery store or the local Walmart, choosing the appropriate stock at your local home improvement store or lumber yard can really make a difference.
While the grading discussed above is important, size is often critical.
One hardwood vendor in Houston that I like has a room relegated to what carpet shops call remnants—off-cuts from orders that are too small for big projects like entertainment centers, but a treasure trove for box-builders.
For example, a couple of years ago I got a beautiful length of zebrawood that supplied the goods for several small projects. See the drawer faces on the box in the photo at the top of this article. I carved the drawer pulls out of rosewood that I picked up on the same shopping trip.
If you are not lucky enough to live close to a store that stocks exotic wood for your projects (i.e. not Home Depot) I suggest you try ordering from Rockler Woodworking and Hardware. The bottom line? Consider what you really need and pick through the stacks!