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Reversible adhesive or not4/3
I am making eleven replacement columns, approx. 8 feet high by 12 inches in diameter at the base, plus bases, capitals, and plinths. The columns are to be made from ten tapered staves each with a spline, 1/4 inch by 5/8 inch between each pair of staves set in a dado that is slightly larger than the spline itself in the beveled stave edge. The original columns are over a century old and appear to have no glue in the joints between the staves or on the splines or in the dados. I assume that there was hide glue in these areas and it has disappeared due to time, moisture, insect or microbe activity, but it could be that there was no glue. (Is that possible? To make columns this way without glue?)
My client wants me to use the same construction that was used in the original columns to maintain historical accuracy and adhere to historic preservation guidelines. This would mean not using glue, or using a reversible glue, such as hide glue.
I am having difficulty imagining assembling the columns using hide glue. I fear the glue would cool and harden long before I could get all the staves together, even just doing them in pairs at a time. Eight feet is a long glue line in hot glue!
Is there another glue I should consider or should I get several assistants and several hot glue pots? Is there another glue I should use, reversible or not?
Normally I have used resorcinol glues for my exterior posts and columns, but it is getting very hard to find. Dural have stopped making the Marine Glue I currently use and I am still looking for alternatives there, but this request for reversibility, or a not-glued assembly has me baffled. I need enlightenment.
I like epoxy for exterior / large glue-ups. It can stand the weather, has plenty of open time, doesn't hurt to be squirmed for better alignment, so long as it is still flexible, bridges gaps.
I have never really bought into going with glues which can be reversible. I'm more of a "if it isn't broke, don't fix it" kind of guy. I'm not sure why anyone would want to take something apart that is holding up well.
However, epoxy can be softened with heat. Although, wood being a good insulator, it is hard to get enough heat to a deep glue-line, without likely doing damage to the wood.
You can mix colloidal silica in to thicken it, which helps it stay put, and bridge better, as well as less brittle.
Even though your columns are replacements for historical ones, I don't think reversability or original construction techniques are desirable here.
Franklin, makers of TiteBond makes liquid hide glue (long open time). It has a "shelf life" & container s/b dated. One can add urea to hot hide glue to extend the open time. "Liquid" hide glues are used extensively today in marquetry on fine furniture & in restoration/conservation of antiques. Your client is paying the bills & his criteria are not a crime so honor the commission you will be both be happy & aapologize to no one. Good luck & enjoy.
I'd be a bit worried about columns with loose splines and no glue. Was this what you found? Or were the splines tight enough to hold things?
Do these columns take weight, or is there a load bearing post in them, or other mechanism? If they are structural in any way, all the codes I know of insist that they still be structural— history be damned.
While liquid hide glue might hold for a while, I would not think it would be good for outdoor work. Check with Franklin Tech Support before using it. And I can't imagine the client would be happy if he had eleven bundles of staves ten years down the track.
It is true that the work of gluing should be kept from too much glue excessive that can impact to the antique art look at joints.
Becuase the glue is applied on the adherent substrates and then and is hiden when we attach two parts of the joint.
I think you can use the epoxy glue or PUR glue that can help long time exterior service.
First: Many thanks to all of you who have responded. Here's my update:
Bolstered by the responses, I have come to an agreement with my client on how to proceed. All of the new columns will be glued with a modern glue of my choice. He now recognizes that the new columns are not themselves historical, though they may be so in 100 years! As such, making them by today's best practice makes sense to him, now.
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, so this will give me a chance to see how the epoxy mix behaves and what issues I may have. I plan to try a bit of thickening agent to help control glue slumping.
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 without glue, and one with hide glue, as an academic exercise. At least I don't have to!
When using splines without glue it is important to make sure that the splines are essentially bone dry. Doing this will mean that as they increase their MC, they will expand, etc. This was a common procedure years ago...before I was born.