I have removed several badly deteriorated 100 plus year old columns that I need to replace, disassembled them, and examined the staves and splines. My client wants the replacement columns made by the same methods to follow historical preservation guidelines. I cannot detect any signs of glue in any of the dados in the staves, on the staves' bevels, or on the splines themselves. I know that hide glue will break down, but I expected to see some signs of glue having been used. Is it possible that these columns were assembled without any glue? If so, how did the makers keep them from coming apart on their lathes?
(Architectural Woodworking Forum)
From contributor B:
True, "hide glue will break down" (along with all animal or vegetable-based glue). So what do you suppose is actually happening to the glue when it is in the process of breaking down?
Answer: Microorganisms are ingesting and digest the glue (which is pure protein and starch) and leaving nothing behind (which isn't being re-ingested and digested over and over again). Add a little rain-water rinse and viola - the mystery of the disappearing glue. Crack an egg, splatter some milk, or smear a bit of fish or animal fat on a stick of wood and leave it outside for the next 100 years or so. Of course it disappears (just not before your very eyes).
I would work towards convincing your customer that some 21st century glue like TB III would be good for columns, good for historical, and good return for expended resources. The original makers would have used it if it was available. If you want to be truly historical, you could come down with yellow fever in the middle of the job.
I am about to conduct a trial glue-up using epoxy. I am concerned about the open working time I will have to assemble long staves with splines. Epoxy should provide lots of open working time, but I will need to control starving the joints during clamping and controlling slumping-likely I'll use a thickening agent in the mix. My client, for his part, has taken a bunch of the old staves and splines and plans to try cleaning them up and attempting to build a new, old column. One he will do without glue, he says, and one with hide glue, as an academic exercise. At least I don't have to!
After a hemisphere of staves are set in place I set circular plywood discs at each end which are equal to the inside diameter of the column staves. This supports the assembly of the upper half. Strap-clamps complete the job. The plywood discs are knocked out before the clamps are fully tightened. Working this way, the whole column shaft is assembled and clamped within a few minutes. A pair of extra hands makes the job much easier. I don't normally use epoxy, just any waterproof glue, straight from the squeeze bottle.
I also recommend seal-coating the inside surfaces of each stave prior to glue-up (and full sealer to the completed column before shipment.) Wood columns should always be installed immediately upon arrival to the job-site and not allowed to lay around under the sun. (This should always be stipulated in writing and signed or initialed by the customer). The staved shaft is then ready to be turned full-round (with the proper entasis). Paper glue-joints can be employed for half column requirements. The caps and bases are turned separately on a face-plate. Manufacturing wood columns is fun but any mistake can spell doom. Proper installation is also essential as exterior columns need to be vented both at the base and head.