Retaining original surfaces

By Bruce Luckhurst

retainingoriginalsurfaces-1Students studying advanced restoration techniques are often presented with the problem of re-jointing panels or table tops without removing any of the original surfaces.

We have all seen the result of unskilled restorers biscuit jointing or dowelling panels out of register to then scrape the surfaces level, hopefully leaving some of the veneer intact. If this restorer is fortunate enough to be the finisher, various pigments are liberally applied to try and balance the difference in hue that has resulted from their previous efforts.

When instructing, I have to design procedures for my students which can be dismantled easily, reversed, adjusted or reduced. Re-jointing panels is no exception and the jig illustrated has made this delicate operation controllable, adjustable and if necessary reversible.

retainingoriginalsurfaces-3A re-jointing jig has to have the following capabilities:

  • Be long enough to accommodate most table tops.
  • Deflect as little as possible.
  • Provide multi pressure points both sides of the joint to be glued.
  • Accommodate register changes along the length of the joint as well as the width.
  • Allow sideways pressure to be applied.
  • Allow controlled re-heating of the glued joint.

When I designed this jig, I intended the face sides to be put face down assuming that the surfaces would naturally come into register if pressed onto a flat platen. In practice this did not work and we now joint with the face side uppermost.

retainingoriginalsurfaces-3If there is a need for some adjustment of the register, packing placed beneath one half of the panel to be re-jointed which will compress slightly is usually enough to provide the adjustment necessary.

We do not use any biscuits, dowels or dovetailed inserts when re-jointing. I consider the practice of cutting dovetailed crossgrained inserts into the panels archaic, invasive and verging on vandalism. Dowels and biscuits give little opportunity for later register adjustments and make it virtually impossible to dismantle the joint without major surgery.

We would like students to use fish glue when assembling joints and laying veneers as this cold gluing system has the latitude required both in assembly time and reversibility. Again, in practice we have found that applying heat the following day to adjust a register or put a frame out of wind makes the glue ’lock’.

retainingoriginalsurfaces-4I intend to do some tests with Franklin Hide Glue to see if it has the strength to hold restored chair frames together, allow adjustment and observe the pull-down time when using it for veneer patching. If any members have experience of this product I would appreciate their comments.

I am fortunate in having a short course student (Robert Davey) who has photographed this jig in operation during a recent cabinet making part three, furniture repair course at The Little Surrenden Workshops. The project is the top of a fold-over tea table. The pine groundwork was cleated in oak with a cross-grained mahogany moulding tongued into the cleat. Needless to say the mahogany veneer had split and lifted. The images show enough detail for a similar jig to be made by any enthusiastic welder with a couple of RSJ’s in the breakers store!