Gluing Reclaimed Heart Pine
Heart pine can be loaded with pitch that interferes with glue joints. Here's some detailed advice on preparing the joints and selecting an adhesive. March 4, 2007
A customer that we did some built-ins for had some old reclaimed heart pine (at least a century old) put in her floors, and was given a chunk of leftover drops, and wants me to make her some woodturnings with it (she's seen some of the work I do on the side). I've never used heart pine for anything, so can this 3/4 material be glued? I've done a handful of segmented turnings with woods certain to hold glue well, but I don't know about heart pine's holding capacity. Any advice? Using Titebond II or a polyurethane glue if needed.
From contributor D:
I work with pine quite a bit, mostly ponderosa, sugarpine and lodgepole. I believe that the old heart pine floors were milled from southern yellow pine, which is similar to ponderosa, which is a western yellow pine. Glue is always my choice for fastening pine, even floors. Plain old yellow carpenters glue is what I prefer with pine. The end grain will glue up good if you rub some glue into the grain and let dry. Then glue away as normal. The edge or the face glue up great, and as a matter of fact, I've tried to break these glue joints plenty of times, and have always broken the board along the grain, not the joint. You mention that the boards are full of pitch, but if the boards are really that old, the pitch is well cured and wouldn't be a problem (though I doubt that the pitch would be a problem even if it were still green, because I have done this as well).
From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
It would be common that the heat from the saws would melt some of the pitch that would be hard at room temperature. When heated and melted, the pitch flows to the freshly cut surface and makes it hard to glue. For the strongest joint, you need to remove the pitch with a solvent before gluing (solvents for teak have been discussed before and should be in the archives) or you can lightly sand the surface (no heat) before gluing. It is my impression that a PUR adhesive will often work well in spite of this resin - try a few test pieces and see.
From the original questioner:
Thanks. I'd sure hate to find out the hard way that glue doesn't hold heart pine well, especially on a laminated blank turning a 10" bowl. Looks like I'm in the clear, so I appreciate the help!
From contributor F:
I would be interested to hear what type of glue you used and how it turned out. I have some heart pine I sawed with my Wood-Mizer and want to turn it too. But the blanks I've cut have hair-line cracks and I am hoping CA glue will work for me.
From the original questioner:
I haven't done it yet. CA glue should take care of the cracks just fine. Be sure to use thin CA.
From contributor A:
I live in heart pine country. It is not like the other pines. The heart will often have a very high resin content. I have built many stairs with it. I have tried most glues and the only one I have never had a problem with is West System. If the resin is so thick that it cakes up on the wood when planed or sawn, I usually wash it off with lacquer thinner, then glue up the treads. Most of my work deals with geometric types. I make them about an inch or two longer than needed. When I cut them to size, I have scraps an inch or so long that I break to see if it breaks on the glue line. I have never had a glue failure with the epoxy. I have had several problems with the other glues. I recently finished an open well hole stair made of Brazilian cherry and used urethane. Big mistake. Never again. Every scrap broke at the glue joint. I have one tread glue failure that I know of as of now. I joint all of the wood that the treads are made of and during the dry fitting, if the joints do not fit as near perfect as is reasonable, I re-joint until they are right before glue up. I don't take shortcuts any more and I use only West System; it works for me.