Popular Woodworking 2005-10 № 150, страница 21

Q & A

continued from page 16

Common hardwoods don't contain "natural" oils. Only afew exotics such as teak and rosewood contain oil, and these oils cause problems for gluing and finishing. They don't need to be replaced. Wood contains water, and the expansion caused by exposure to moisture, and shrinkage accelerated by the sun, has likely caused splitting.

If the wood is splitting, you can't do much about it. Just paint or finish over the splits. Only if you paint should you try to fill the splits. Filling the splits will look awful under a clear finish.

I would imagine that the wood is gray, at least the parts that were exposed to the sun. When you get all the oldfinish removed, sand the wood lightly. Then apply oxalic acid, a wood bleach you can buy in crystal form at home centers and paint stores. Dissolve the crystals in hot water to saturation. Let the solution cool, then brush it onto the entire pew. After the solution dries, hose off all the crystals. Be careful to not breathe them. Oxalic acid is mildly toxic and will cause coughing and choking.

When the wood is clean and dry, sand it smooth. Then finish it in any way you want. Three or four coats of boat varnish, available from marinas (jamestowndistributors.com, for example) will be the most effective clear finish for resisting damage from the sun. (Wax will offer no resistance to either moisture or sunlight.) Paint is best, however. It totally blocks sunlight.

— Bob Flexner, contributing editor

How Do You Calculate the

Board Footage From a Materials List?

I recently bought plans for a curio cabinet. And while the plans contain a cutting list, there's no shopping list. Fortunately when I build projects from your magazine, sometimes a shopping list as well as a cutting list is supplied. Is there a simple way to find out how much material you will need for a project, when it is not given?

Eddie Dunlap East Elmhurst, New York

Calculating board feet needed for any project is as much art as it is science. In theory, if you multiply the thickness of each piece (figuring ³A" thickness as 1") times the width, times the length, times the number of pieces, you will have the cubic volume of the parts. Do this for every part, and you will have the total volume of material for the finished parts. A board foot is a measure of volume, equal to 144 cubic inches. If you divide the volume from

your calculations by 144 you will know the board feet in the finished parts.

The pro blem with this method is that it doesn't take into account any waste factor. Hardwood is sold in random widths and lengths, so until you look at individual boards, and decide which parts will come from which board, you can't be sure how much material you will need.

It can be tedious to work through the list. What I usually do is go through it quickly by

rounding up to the next whole number. When all of this calculating is completed, I add afactor for waste, somewhere between 15 percent and 40 percent of the total.

The alternative is to take your list with you to the lumberyard, and as you pull boards, figure which parts can come from each piece of lumber. Some people go so far as to mark them out with chalk, or put PostIt notes on the boards. PW

— Robert W. Lang, senior editor

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