Fig 1. When using a manufactured board as a base it is best to ftp around it with solid timber. Glue the lipping, cramp it and allow it to set

Fig 2. The lipping is slightly proud of the surface of the ground so trim it flush with a very finely set plane

Fig 3. Even man-made boards display a certain amount of unevenness .Shoot the surface absolutely flat with a longer jack plane.

Fig 4. The quality of the finished work can only be as good as the ground work beneath. To finish, run an electric orbital sander over the surface

Fig E. If you apply a lip before you veneer, it will be covered but the veneer left vulnerable. If you apply the lip after, the veneer will be protected.

Fig F. If you apply only one veneer, fix it to the heart side of the timber to counteract shrinkage.

As with any craft the finished product will only be as good as the base, or groundwork. Veneers can be stuck on to almost any timber as long as it is even grained, stable, knot free and not resinous. Knots and faults must be cut out and plugged, and absorbent timbers sized with either the same or compatible glue or adhesive as used for sticking down the veneer itself.

It is not advisable to fill blemishes with two part resin wood fillers because they tend to 'shadow' (show through) the veneer when the surrounding groundwork shrinks. On small areas you can successfully use amyi acetate based filler.

Knots are a special problem: because the grain runs through them, they will stand proud when the surrounding timber shrinks. Knots and other blemishes may be either round or diamond plugged and although there are special plug cutters available, these can cope only with small areas.

To round plug, simply drill out the knot with a suitably sized bit, then fill the hole with a plug of wood. Do not use a dowel because it will behave exactly the same as a knot.

Large knots are best filled with diamond plugs. To make a diamond plug, cut out a diamond shaped recess around the knot with a sharp chisel;

then cut a diamond shaped piece of wood to fit the cavity (fig. H). Make the plug thicker than the cavity, and plane it flush once you have glued it.

Due to timber shrinkage you must never veneer over open dovetails, through dovetails or similar joints. But you can get round this problem by incorporating hidden joints into the design of the piece.

Boards should not only be well seasoned but, to avoid them becoming hollow or buckling, preferably quarter sawn. If this is not possible, cut or buy the boards in strips no wider than 75mm and then make a panel by gluing the boards together with the heart sides up on alternate boards.

[edit] Dealing with Distortion

Fig H. Below: To remove knots from the groundwork, plug the timber either with a simple round plug or a diamond.

When veneer is stuck down, it pulls the base towards itself; as it dries out, this pulling effect can bow the timber. The effect is more pronounced on thinner base boards but in most cases it is necessary to design a method to overcome the problem.

The easiest way where narrow boards are concerned is to veneer on the heart side; this will overcome the natural tendency of the timber to shrink away from the heart. A better method, where the work is not hidden within a carcase, is to veneer both sides of the piece (counter veneer) though even with this, the board can still warp.

The very best method of veneering, especially on high quality work where a large, highly polished area will be exposed, such as a table, is to double veneer. This simply means laying two veneers to the base material. The first, as normal in single veneering, is laid at right angles to the grain of the groundwork. Allow the glue to set, sand this smooth to remove any blemishes, then lay the second veneer at right-angles to the first.

Although it is perfectly possible to veneer man-made boards, you should use only top quality materials such as plywood, laminated board, block board and high density chipboard (particle board). When using chipboard, you must always counter veneer.

One problem common to both man-made boards and natural timber is that it is very difficult to make veneer adhere to the end grain. And, even if you do get it to stick, the laminations and chips of manufactured boards tend to shadow through the veneer after a short period of time.

The best way round this problem is to apply lippings to conceal the edg­ings. Whenever possible use a lipping timber of the same species as the veneer; this not only saves veneering the edge, but enables the edges to be moulded if required.

You can lip either before or after the veneer is applied. In the former case the lip will be concealed; in the latter it will protect the vulnerable edge of the veneer. Always make the lip 1-1.5mm proud of the base surface, and then plane it flush once the ad­hesive has set.

The importance of a perfectly smooth ground surface for the veneer cannot be overstressed. To achieve a perfect finish, plane the surface ab­solutely flat with a jack plane.

When using the traditional hot animal glues, it is necessary to rough up the surface of the board with a special toothing plane; this process has the advantage of revealing any hollows which can then be dealt with. But with the modern cold resin adhesives you have only to lightly sand the material and then clean it thor­oughly. In this case, therefore, you must test for any unevenness in the surface with a steel straightedge. Take care when planing the boards not to round the edges. If you have to size the board because it is absorbent, you must sand it smooth again and clean it before applying the veneer. The best method of sanding is to use a large orbital sander, taking it first at right-angles to the grain and then diagonally across it.