Monday 12 January 2009
Highly decorative effects can be created without resorting to complicated techniques says Ian Hosker
Highly decorative effects can be created without resorting to complicated techniques, simply by matching the patterns of adjacent veneers. Part of the aesthetic quality of using veneers is to make the most of what the veneer has to offer with its colour and grain.
Because of the thinness of each leaf of veneer, consecutive leaves have more or less the same figure pattern, and it is this property on which veneering patterns rely. Even if the area to be covered is relatively small, where a single leaf would normally be enough for the job, you will still need consecutive leaves. This means that you may only use a small area of each leaf, so these methods do tend to be wasteful, and thus expensive. However, through careful choice of veneers, or areas of veneers, you may be able to save sections large enough to use in other projects.
The most important feature of highly decorative veneers, such as curls and burrs, is their uniqueness. No two pieces of veneer are exactly alike, but with highly decorative veneers, the difference is even greater. Even consecutive leaves will differ slightly, but usually not enough to be clearly noticeable.
While the most striking decorative effects are created by matching consecutive leaves of highly figured veneers such as curls and burrs, straight-grained veneers can also be used. It is tempting to use just one sheet to create these effects, but that would be a mistake because the figure is not identical along the whole length of a leaf. This is hardly noticeable when viewing the whole sheet, but some very odd looking effects result if you start attempting to book-match or quarter.
The safest plan is to use consecutive leaves in all cases of mirror image or other veneer matching techniques. This is considerably more expensive, but as mentioned before, you can plan the work to reduce wastage and even to use the remaining sections in other pieces. In addition, one sheet can be cut to produce multiple panels. For example, by cutting two or four consecutive leaves down the middle, two book-matched or quartered panels, respectively, can be gained, giving the materials greater value for money. When cutting packs of consecutive veneers, remember that you must keep the leaves in perfect alignment so that the figure of each leaf coincides.
Mirror imageThe decorative effects of book-matching and quartering are based on the mirror image principle. In book-matching the mirror image is created by opening two consecutive leaves like the pages of a book, while for quartering, four consecutive leaves are used to create the mirror image twice.
Preparing the veneersWhile it is possible to lay book-matched or quartered veneers by hand - i.e. using pearl glue and the veneer hammer - there is the risk that they will not match at the joints, because of the need to cut through the overlap, which almost always results in a slight mismatch. For this reason, it is best to lay book-matched or quartered panels with a press.
Laying book-matched panels1 Carefully position two consecutive leaves of veneer on top of each other, so that they are oriented in the way they came off the veneer cutting machine. Keep their edges closely aligned to ensure that the figuring of the two leaves coincides.
2 Choose the area of figure that you wish to use, planning your work carefully, and cut the pack to size, leaving a slight overlap to allow for final trimming. A veneer knife or saw can be used for this, with a straightedge, though the saw is often better for this trimming work, especially with hard or highly figured woods. You may find it helpful to tape the pack at the edges, to keep the veneers in place.
Remember when you are planning the cuts, that after opening up the leaves, the final size will be double the width of the pack. Be particularly careful when cutting along the side that will form the joint between the two veneers, because any splintering will require trimming, and this may result in a noticeable mismatch.
3 Trim the joining edges of the two veneers very finely, on the shooting board: the edge produced by the knife or saw is unlikely to be good enough, especially with long joints. Do not overtrim, just skim the joint, because the more you remove, the greater the mismatch of figure after joining. Leave the tape on, to help hold the veneers together, and use a batten of wood to hold the edges of the veneer flat and steady.
4 Open out the top veneer, as though turning the pages of a book, to form the mirror image, then fit and tape the joint. Take great care that the figure of both veneers lines up exactly at the joint, or it will look very odd.
5 Lay the veneer carefully and accurately.
Laying quartered panels1 Carefully position four consecutive leaves of veneer on top of each other, orienting them in the way they came off the cutting machine, and keeping their edges closely aligned to ensure that their figuring coincides.
2 Choose the area of figure you wish to use: you need to visualize the completed pattern because the veneers must be positioned in a particular way in the pack in order to achieve that pattern.
3 Cut the panels to size as for book-matched panels. This preparation of the veneers does require great care, as there will be two joining edges on each piece, and they must be at right angles to each other, though the initial cutting of the quarters can be approximate to within a few degrees.
Hold the veneers firmly in place with tape as you cut. The four layers take some cutting through, so it is better to use a veneer saw for this to ensure a neat job.
4 True up the joining edges, on the shooting board. Keep the tape on and use a batten to hold down the veneer, to ensure that the pieces do not slip. The fence of the shooting board is at 90 degrees to the edge of the board, so to ensure that both edges are at right angles to each other, trim one jointing edge and then hold that edge firmly against the fence while you trim the other. This is vital if all the edges are to make good joints.
5 Open out the top two veneers. Join the edges A-A and B-B together to reveal the quartered panel.
6 Assemble the veneers very carefully, ensuring that the figure and joints are accurately aligned, then tape up the joints securely.
7 Lay the veneer carefully and accurately.