Just cut the pieces for a new entertainment center in cherry ply. While trying to pre-think myself out of possible problems I remembered that when I built a solid cherry table top the glue (Titebond II WeatherProof ) that I used to edge glue the boards seemed to expand out of the joints for some months after the table was put in use. This top was finished with Watco Danish Oil. Re-sanded top, no more problem.
I plan on again using Titebond II, and the Watco finish, and I am concerned that if I get the same glue expansion problem it will be very difficult to re-sand the project, and is this glue expansion a symptom of some sort of glue deterioration? Does anyone have any experience with this combination? What about the Watco finish affecting the adhesive used with iron-on edge trim?
I am primarily a large nail-banger, so I am not sure if I should use some sort of sanding sealer before the Watco. Any advise on any or all of my concerns would be greatly appreciated.
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I also used Titebond II for all my woodworking until I took a solid case construction course with Kelly Mehler. He strongly recommended plain white glue (Elmer's) or hide glue due to the moisture content and set up time (hide glue gives you a little more time to get the joint right before it begins to set up). I still use Titebond II for plywood but when it comes to solid wood I have switched to hide glue. Not sure why your joints continued to ooze but these glues do have a shelf life.
Titebond is water-based. Wood swells with water. Wood dries and shrinks. Glue line doesn't and you can feel it.
I used to make my laminated items and store them final-sanded but unfinished for a month in a heated room. Glue lines would surface, i'd hit them with a fine sandpaper and finish as usual.
Now i use poly glue and forget all that hassle. Clamp time is crucial, though. Just leave the stuff clamped up at least 24 hours and you should be fine.
Here is one of the best write-up I have seen on the subject. The shop I was involved with stopped using PVA adhesives for panel construction a number of years ago. We switched to urea plastic resin or casein glue for panel glue ups and eliminated all call backs.
Creep has been known about for many years, perhaps even centuries. It's nothing new and has already been defined precisely, so no need to reinvent the wheel here. PVA is the classic and renowned creeper.
The tendency of the glue to ooze out of joints is one form of creep. A classic example is in a slab edge to edge glueup, such as a table top. When ambient humidity rises the timber and the the glue swell. When the ambient humidity goes down the timber shrinks again, and so does the glue, but the glue doesn't all shrink back into its original place resulting in a line of pimples disfiguring the finish. Actually, under sustained high humidity my anecdotal observations are that the glue keeps on absorbing moisture and creeps out of the joint without the need for the timber to shrink. The symptoms can also be seen sometimes at the shoulder line of other joints such as mortise and tenons.
Another cause that I've witnessed several times is to make a solid timber slab with edge joints in a fairly humid workshop without climate control using PVA as described before. Then right away get to planing and preparing the surface ready for polishing with scrapers, sanding, etc.. Right after that apply the polish, whether it be varnish, pre-cat, or another finish, and take the piece into a drier house, either heated or air conditioned. Three to five days later the rows of pimples will be apparent as the timber shrinks.
Somewhat related to this is using an aid for edge glue alignment, such as biscuits with PVA. These jobs need time to settle. If you are in too much of a hurry and prepare for and polish it all as soon as you get the piece out of the cramps, the chances are you'll see a row of rugby ball shaped depressions telegraphing the position of every biscuit a couple or three weeks later, although I've seen them appear as much as a year, or more, later. The moisture in the glue swells the wood either side of the biscuit, and it takes a week or two for this moisture to work its way out of the joint properly. My advice then is to not rush into the preparing for and polishing stages after this type of glueup, particularly table tops and the like which show off every flaw. I don't use PVA for this specific kind of glueup at all anymore here in hot, humid Houston. I tend to reach for the hide glue nowadays, either out of the pot, or the liquid stuff. Slainte, RJ.
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