| Several types of superior wood products have been | | | | of interior plywood). Two letters are used in the |
| developed by modern technology. The majority are | | | | grading of a sheet of plywood - one for the face |
| wooden "sheet" materials - flat sheets of laminated | | | | and one for the back. Where only one side will show, |
| or compressed wood products that are generally | | | | it is economical to use A-D, with one good side. |
| stronger, more flexible, and less likely to split than | | | | The biggest job when working with plywood is |
| ordinary lumber. They expand and contract less than | | | | usually cutting the large panels to size. If you will be |
| common lumber and are available in large sizes | | | | cutting several panels from a full-sized sheet of |
| (usually 4 by 8-foot sheets) that would be impossible | | | | plywood, it's a good idea to draw the sections on a |
| to mill and distribute in the wood's natural form. They | | | | piece of paper and transfer the marks onto the |
| are sometimes available in half sheets (4 by 4 feet) | | | | plywood. Always double-check measurements to be |
| or odd sizes. All of these products fall under the | | | | sure they are correct, and don't forget to allow for |
| categories of either plywood or hardboard. | | | | the saw kerfs (width of cut) between pieces. If you |
| In effect, plywood is a sandwich panel of real wood, | | | | plan to cut the piece with a handsaw, power radial or |
| made from an odd number of thin sheets of wood | | | | table saw, mark on the better face of the plywood |
| laid with the grain running in alternate directions and | | | | and cut it with this side up. If using a portable power |
| bonded under pressure, glues, and sometimes heat. | | | | saw, mark and cut the panel from the back side. Plan |
| There are several types available to the home | | | | to reduce the sheets to workable size with the first |
| craftsmen that are excellent for the construction of | | | | cuts. |
| furniture. | | | | Power saws are great for cutting plywood. Radial, |
| Douglas fir plywood is the least expensive and most | | | | table, and portable power saws are extremely helpful |
| commonly found type. It is available in two types - | | | | in cutting straight lines, jigsaws, band saws, and saber |
| interior and exterior - depending upon the glue bond | | | | saws cut curves easily. If you cut plywood by hand, |
| and grade of veneer. | | | | choose a keyhole or coping saw for curves and a |
| The inner piles of exterior plywood are all of high | | | | handsaw with 10 to 15 teeth-per-inch for straight |
| quality and bonded together with completely | | | | lines. Special plywood blades with fine, shallow-set |
| waterproof glue. This type of plywood will resist time | | | | teeth can be purchased for power saws, to aid in |
| and weather - even when boiled in water it will not | | | | making clean cuts. Be sure all saw blades are sharp. |
| decontaminate. Interior plywood is water-resistant | | | | There are several methods used to help prevent |
| but not waterproof, so should not be included in | | | | plywood undersides from splitting-out when being cut. |
| projects for permanent outdoor use. | | | | Both sides of the panel can be scribed through the |
| All fir plywood's (particularly rotary cut types) have a | | | | top veneer along the cut-off line with a sharp knife |
| tendency to check when used outdoors. These | | | | or chisel. Or, you can carefully tape along bottom side |
| should never be used outdoors with only a stain | | | | of cut -off line with cellophane tape. When |
| because of the maintenance problems. Checking can | | | | hand-sawing, put a piece of scrap lumber under |
| be reduced by careful painting with a conventional | | | | plywood and saw both together. |
| three-coat paint system. Edges should be daubed | | | | To keep wood from splitting-out when boring holes, |
| with a heavy coat of primer or a thick mixture of | | | | either clamp a piece of wood on the back of the |
| white lead and oil. Warping may become another | | | | plywood or turn it over as soon as the point of the |
| problem, but is less likely to occur if the panels are | | | | bit appears through the backside and finish drilling |
| stored in a dry place and finished identically on both | | | | from the back. |
| sides. | | | | To plane plywood edges (a job that isn't usually |
| Standard fir plywood thicknesses are ¼, 3/8, | | | | necessary), work from both ends toward the center |
| ½, 5/8 and ¾ inch. Some large lumber | | | | using a sharp, shallow-set blade. If possible, cut a tiny |
| distributors also carry 1 1/8 inch. | | | | bevel at each corner to help prevent edges from |
| Quality of face and back panels determine the | | | | splitting-out. |
| grading of fir plywood. Letters A, B, C and D indicate | | | | Sanding surfaces of plywood is not necessary - it |
| the different grades. A is the best quality, B is | | | | only removes soft grain. When sanding edges, use |
| smooth (excellent for painting), C has knotholes and | | | | finer sandpaper. |
| splits, and D is the poorest (often used for inner ply | | | | |