I have glued a lot of mahogany veneer to some 8″ sewer pipes in order to make some false columns. They looked great until a couple of days after I stained them, when they all rippled. The plastic pipe was sanded before lamination, and the glue used was red spray on adhesive used in post-forming.
since then i have also used water based contact cement, 3m spray 90, pva glue in a vacuum press (which worked but was far too slow for production)
Other than the pva everything bubbled eventually.
any solutions?
Replies
Did you scuff the surface of the PVC? Sounds like a mechanical failure of the glue bond.
j.p., he/she says right there in the question that the PVC pipe was sanded.
This seems an unlikely mix of materials to achieve success-- pvc pipe, veneer, bonded to each other with impact glues of one sort or another! It sounds like a recipe ripe for failure, and not a routine I'd even countenance, let alone actually attempt with any hope of success.
My guess is that the veneer is being polished with solvent or oil based products which are reacting and weakening the glue causing it to release its grip resulting in bubbles and failure. This might explain why the PVA glue-- water based-- held rather better than other glue choices.
jz, It looks like you need to completely rethink this project. The plastic pipe, creepy glues you're using, and the wood veneers really don't like each other much in the first place. About the only glue I can think of that stands a half-ersed chance of working here seems likely to be an epoxy resin formulation-- or maybe a last gasp effort might be a hide glue of one sort another, and both those choices can be a bit tricky.
I might investigate the possibility of bonding some veneer with PVA to cardboard columns? Wood to paper (card, aka, wood product) with water based glue. It must be a column for an interior project because no-one would use the materials you're experimenting with for an outdoor situation anyway, ha, ha, so a cardboard tube as used in foundations and the like ought to be able to provide any columnar strength required. Slainte.Website
To add on to Sgian's post, you can buy plywood or fiberboard tubes from Anderson International (http://www.aitwood.com). They're intended for exactly this application, and are easier to work with than the Sonotube Sgian mentions. AIT also offers the tubes already veneered.
Check back through Fine Woodworking of a few years back as there was an article on this idea of making columns from plastic pipe. If my memory is working I think the woodworker glued a secondary wood to the plastic with epoxy and then glued the veneer to this.
Here's a source for veneered plywood tubing:
http://www.hollowoodinc.com/
PVC cores aren't a great idea for wood veneer because the plastic is subject to a lot of movement with temperature changes.
Looks like the hollowood link in post 6 is an answer, assuming the money angle is OK. But for the sake of discussion, I'm wondering if paper-backed veneer or perhaps cross-banded veneer would work, ignoring for the moment the temperature induced movement of the pvc pipe.
Sophie, there might be some advantage, particularly with using the paper backed veneer. This might bend around the desired curve easily enough with some dampening something along the lines lumo described. Applied with an impact glue, the paper would create something of a barrier between the glue and any solvent based finish/polish that's used on top.
There are some interesting problems with these types of impact glues (or contact cement to use the US parlance.) The most effective ones I've found are solvent based-- I've never had any real success with water based impact glue, and the bond can be attacked by the solvents used in many finishes. For exampe, the inevitable dribbles of glue used to apply plastic laminates is usually cleaned off with lacquer thinner, a constituent of a significant family of polishes.
The two ply veneer you mentioned might work too, especially in its ability to create a barrier as before, but now you are dealing with a stiffer material that might be too rigid to bend around a tight curve and be held down by creepy impact glues--- depends on the curve of course. Creep in impact glues can cause quite a few problems, even when used for plastic laminate for which they are ideally suited in many respects. Misaligned corners is just one failure sometimes seen where the glue allows the laminate to expand or contract as relative air moisture content changes which can affect both the groundwork and the laminate.
A difficulty with many glues used for this kind of job is actually wrapping a veneer successfully around a tube and creating a neat seam in one operation-- it's exceedingly difficult to do in a small workshop lacking factory type mass production control as used for producing veneered columns as mentioned earlier by Jamie, I think.
Glues that dry hard and rigid such as urea formaldehyde, or glues that grab instantly such as impact make it very hard to get a perfect seam, and lumo again highlighted one significant advantage of using glues that can be reactivated-- hot hide glue is a classic for this type of technique where the veneers are overlaid and later sliced through to remove the overlap, and he/she described it well.
PVA is another glue that can be reactivated, but with PVA you really get only one shot at reactivating it and creating a seam, whereas hot hide glue gives you multiple shots at the job because you can add more glue which reactivates or replaces the earlier applied stuff and press down again. I haven't used cold liquid hide glue for specifically for this type of procedure, but I've heard that it works too.
In the end though, the plastic pipe is not a good base upon which to veneer, and a better base would be the cardboard tubes I mentioned, or even better again, the ply or MDF tubes as suggested by Jamie and Bill Duckworth. Slainte.Website
Thanks to you all! A lot of great information. I wish I'd known about the cardboard tubes before, didn't want to use sono tubes (because of the seam). I tried, on the plastic tubes, many different adhesives, and in the very end, found that the really stinky old original brush-on contact cement was the stuff to use. So far, no problems. I had laminated a total of 58 tubes with the original contact cement before they all started rippling, and it took me a lot of time and money to figure this one out. Thought I knew it all, but should have come here first!
next time, thanks again.
Just as Sgian said cardboard will work.
I've used carpet roles in the past,to cover up a steel pipe in the basement at my house.I used barebacked veneer, it worked out great.
I hope your project works out too.
sincerely. C.A.G.
The principle that you describe is spot on , but as mentioned by others the choice of glues is the problem . I restore furniture and have in the workshop a piece which needs 2 columns re-veneered .The way which works is to wrap the veneer around the column and wet the veneer through, tie firmly in place , leave to dry , remove the bindings , now the veneer can be worked on to the column with hide glue , cut easily along the join and any lumps and bumps can be eased out with the iron. Some of the older methods will stand the test of time , i see this everyday. Good luck with the columns. Lumo.
This forum post is now archived. Commenting has been disabled