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After being unloaded from the press and after cooling, panels are trimmed to precise sizes usually by passing through two sets of parallel gauged circular saws. The edges of an untrimmed plywood panel are more irregular, for example compared to particleboard. So the panel is ether introduced into the trimming saws by hand with the aid of shadow lines, or greater trimming margins must be allowed. This ensures that panels are rectangular and straight edged.
The wide belt sander has been used to an increasing extent. These machines have been developed from the large metal finishes used to produce flat and polished surface on sheet metalsBaldwin (1981). Their development for plywood finishes allows the manufacture to produce high quality finishes at high production rates. The machines are available with one or several belts wit feeds speeds up to about 30m/min being possible. These machines can bring the stock to its final required thickness as well as provide a final finish. For this double task the panel may best be sanded by two or more belts, or given serval passes through a single head machine with finer grit papers for each succeeding operation. The top belt machine is more commonly used over the bottom belt machine as the operator can continuously observe the panels surface. After sanding, boards are graded for defects.
Vessels in hardwoods in oblique or radial chains can give trouble later in sanding and finishing. Loose cut veneer can affect the decorative value of the final product by the cracks extending with time through the face and so marring the polish.