Popular Woodworking 2001-02 № 120, страница 21
Flexner on Finishing The Best Way to Reglue Furniture Quick fixes never last. Here's how to make sure the joints in your antiques stay tight. Of all the steps involved in restoring old furniture, regluing is by far the most important. Poorly done refinish jobs can be redone; badly made replacement parts can be remade and reinserted; sloppy touch-ups can be removed and done over - all without permanent damage to the furniture. But shoddy regluing can, and often does, lead to the complete destruction of the furniture. Despite the importance of the regluing step, only a small percentage of professional and amateur restorers do it well. As a result, much of our old furniture is becoming unusable. Five Methods There are five ways to reglue or "tighten up" furniture. In order, from worst to best, these methods are as follows. • Use nails, screws, brackets and other metal fasteners. • Insert white or yellow glue, cyano-acrylate (super glue), or epoxy into the joints without totally disassembling the furniture. • Disassemble the furniture and apply fresh glue, usually white, yellow or epoxy, on top of the existing glue and clamp back together. • Apply hot animal hide glue over the old hide glue that remains in the joints (after removing any loose or deteriorated glue) and clamp the joints back together. • Clean all the old glue out of the joints, apply fresh glue (usually hide, white or yellow) and clamp the joints back together. In furniture with dowels, remove all the dowels that are loose and either reuse them after cleaning both them and the holes, or replace them with new dowels after cleaning the holes. Even better, replace all the dowels by drilling out those that are still tight but likely to come loose relatively soon. Then clean the holes and reglue the joints with new dowels as if everything were new. Metal Fasteners Inserting nails or screws and attaching metal fasteners is the worst thing that can be done to furniture. Any stress put on the joints can cause the wood to split, and sometimes cause tenons or dowels to completely break off. At best, the fasteners just hold the joints together; they don't make the joints tight. "Wooden nails" (dowels) inserted perpendicularly through a wobbly mortise-and-tenon joint are just as destructive and difficult to deal with as metal nails. Unfortunately, many people find wooden nails somehow romantic, as if these "nails" are evidence of great craftsmanship, so they are sometimes added to old furniture. Inserting Glue Into Joints The practice of inserting glue into joints without disassembling the furniture is very widespread. Three methods are used: drip glue at the edges of the joints and hope it runs into them; drill holes into the joints and insert the glue through a syringe; and pull the joints open just enough to expose small parts of the tenons or dowels and apply glue to them. The glues most often used with this technique are cyanoacrylate and epoxy, though white and yellow glues are also used. Cyanoacrylate and epoxy are more expensive and difficult to use, but it's usually reasoned that they are stronger. Though this method produces joints that usually remain tight for a year or so, long-term soundness rarely occurs because only a part of the surface area is "reglued," and it is still sealed with old glue, so the new glue doesn't get to the wood. Old furniture pints were glued with animal hide glue, which must be removed before regluing with any glue other than hot hide glue so the new glue can bond to the wood. You can easily dissolve and wash off old hide glue with hot water or vinegar. If the glue is stubborn, scrub it with a stainless-steel kitchen scrubber or coarse Scotch-Brite pad and hot water. Disassembling and Applying Glue A better practice is to disassemble the joints before applying the new glue - usually white, yellow, epoxy or polyurethane glue. This method exposes more surface area to these glues, so there's a better chance that the joints will remain tight for at least a few years. But the wood is still sealed with the old glue, so just as with the previous method, whatever bond is achieved is made to the old glue, not to the wood. The bond achieved is thus no stronger than that of the remaining old glue to the wood, and that glue has already given way once. Moreover, when the joints break down again, as they surely will, proper regluing will be much more difficult because all the newly applied glue will have to be removed in addition to the original glue. Using Hide Glue All furniture made or repaired before the 1950s was glued with animal hide glue. This glue is made from the broth of animal skins, usually cattle, and has to be heated to about 140 degrees to be made 30 Popular Woodworking February 2001 |
