Question Corner Glue?

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LaFontsee

LaFontsee

MGF, Master Grumble Framer
Joined
Sep 2, 2009
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Grand Rapids, MI
What do you all use to glue your corners on wood mouldings?

Currently we use Titebond that we get from Home Depot. We are re-evaluating that and would like to know what is popular with the rest of you and why.

We join most of our frames with a pneumatic underpinner if that make any difference.

Thanks!
James
 
We use MAXIM Blue from Frame Specialties. Quick set time and wipes away with a damp cloth.
 
Since MiterTighter's demise, I'm stuck on Maxim black, opaque white, and the typical, translucent Maxim Blue.
 
The wood glues used for framing are generally PVA (polyvinyl acetate) or EVA (ethylene-vinyl acetate) formulations. There are some differences in their chemistry, such as content of solids, which mostly affect the minutes of open time, set-up time, and drying time. However, when properly used, all of the popular brands are stronger than the wood parts they bond.

Usually, framers asking for glue recommendations are experiencing bonding problems. The only reason for failure of the glue itself would be corruption of its chemistry, which is usually caused by freezing, extreme heat, or age-degradation. Most PVA glues in properly-capped plastic bottles will be good for at least two years in good ambient conditions.

Speaking of ambient conditions, the performance of water-borne frame glues is affected by temperature. In summer in a shop without air conditioning, warm glue will have shorter open time, but will set-up and dry faster. Conversely, cold glue will have longer open time, but will set-up and dry more slowly. Of course, if your shop is climate controlled all year round, these characteristics might not matter.

If your glue is separated or watery, it probably has been frozen. Or, if it is very thick or lumpy, it probably has been exposed to extreme heat. Both of these conditions could happen in transit or warehousing before the glue arrives in your shop, but if your glue is not right, just throw it away. Store your glue supply carefully and replace the cap after every use. Leaving the cap off allows the glue to lose moisture over time, which amounts to a slow drying process.

Most of the time, weak or failing glue joints are caused by something other than the glue. Here are some common causes:

1) Applying too little glue. Smear a thin film of glue over the whole miter surface, and after clamping, use a dampened towel or toothbrush to remove the excess that oozes out of the joint before it dries.

2) Moving the joint too soon or breaking the bond during set-up. "Open time" varies among brands, but it usually is around 30-60 seconds. Know the open time of your glue and stop manipulating the joint within that time. Otherwise, the bond will be weakened. For most glues, after about 3 minutes the frame may be handled carefully, but the bond will still be weak. Complete drying (and full strength of the bond) may take an hour or more, depending on the wood and the ambient.

3) Contamination of the miter surfaces caused by something like saw dust, skin oil, cutting oil, or oil-based marker ink. Make sure your miters are cut using blades that are not covered with oil applied to prevent rust after sharpening, or from cutting aluminum. Remove saw dust by wiping with a clean, damp cloth. If you use a color marker on miters, apply the ink only to the very edge, since the glue will not bond well to the inked area. If you use hand lotion, do not touch miter surfaces. (BTW, nitrile gloves work well)

Bottom line:
Use whatever glue brand you like best.
 
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I know this is an old story of mine. I once asked a biblical archaeologist what type of glue he used to glue all the chards together in the field. His response was "whatever is on sale". They used so much, it didn't matter, and in the end, it was the conservators' problem to solve. o_O My cousin is the department head of archeology/biblical graduate studies at Towson Univ.
 
Thank you all for your replies. The info provided by Jim Miller is particularly interesting.

I think the main complaint we have with Titebond is that regular wood glue tends not to be as flexible as we would like. We have recently been having issues with joints cracking, especially narrow, tall floaters. I am confident that using a framing specific glue will help immensely. It seems that the main deciding factor between Maxim, Cornerweld, or something else will be ease of ordering from our suppliers.

Thanks again,
James
 
Lafontsee said:
We have recently been having issues with joints cracking, especially narrow, tall floaters.
Click to expand...
Ah, yes. Floater frames...Please allow me to add one more cause of weak or failing glue joints:

4. Inadequate clamping. If a deep-rabbet shadowbox frame or floater frame is clamped only at the bottom, such as in an underpinner or Stanley-type clamp, the top may not bond properly, even if the miters appear to be closed together. I suggest using a clamp with provisions for deep rabbets (Master Clamp is excellent, but costly). Also, you can securely clamp these tall mouldings using a strap clamp or bar clamps.

After fitting, a floater frame suffers almost no stress at its top, since the artwork is generally attached to its perpendicular "floor", so a secure glue bond should serve the purpose. However, a deep-rabbet shadowbox frame's stress generally is concentrated at the top, due to the weight of glass under the lip. In that case, you probably should consider adding a pin or brad near the top, in adddition to v-nails at the bottom. Or, for the best results on shadowbox mouldings at least 1/2"wide at the bottom, use a Hoffmann dovetail router and insert a nearly-full-length key.

Or, maybe you could do what I did and make your own clamps. I built a pair of these pneumatic babies to join the 40"x60"x 2"deep floater frames I'm asked to assemble routinely. This photo shows an early version with a shallow-rabbet frame, but it works best with deep frames. The current models have 2-1/2" tall vertical plates with screw adjustments in all four corners, to tightly close the miters top-to-bottom when the rails are warped/twisted, which happens a lot. Because two hands are often needed to position the miters, these are rigged to release when the foot pedal is depressed. Stand on it while manipulating the corner (no more than 10-15 seconds), then let up on the pedal, and the clamp closes. Five minutes later, the Maxim Raven (black) or Dove (opaque white) glue is set-up enough to hold throughout fastening in the shop's Cassese underpinner; One 15 mm v-nail at the outside, plus three or four 7 mm v-nails along the horizontal "floor".
Photo-Floater Clamp Pneumatic-LoRes.jpg
 
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What a great idea, Jim. Maybe you could start a cottage industry making those for shops that do a lot of joining of these kinds of frames.
:cool: Rick
 
Jim, I agree with Rick. You have a wealth of talent and ideas that many of us would never think of. We should start a TV show like This Old House but call it ......wait for it......This Old Frame Shop? OK - I'm open for better names for the show!o_O
Thanks for sharing these tips. By the way, I'll take 10 sets of clamps......if I can have them by Monday and I have coupon for 40% off, can I use it?
Darth
 
Jim Miller said:
Ah, yes. Floater frames...Please allow me to add one more cause of weak or failing glue joints:

4. Inadequate clamping. If a deep-rabbet shadowbox frame or floater frame is clamped only at the bottom, such as in an underpinner or Stanley-type clamp, the top may not bond properly, even if the miters appear to be closed together. I suggest using a clamp with provisions for deep rabbets (Master Clamp is excellent, but costly). Also, you can securely clamp these tall mouldings using a strap clamp or bar clamps.
Click to expand...

Or go all out and get a Hoffmann. With the new W0 keys you can go as narrow as 3/16". That IS pushing the limits, but we recently did an order of 42 frames* and had only 2 or 3 rejects because of blow out. No doubt we could have set the spacing a bit looser, but I considered that acceptable considering the circumstances.

*these were cap frames, 5/16 on the face, 1/8 rabbet, leaving 3/16 stem:

2018-04-24 06.49.19.jpg
 
I've always used PVA. The thing is with it, when it has set it is still very slightly flexible. So it will absorb
a certain amount of stress before it breaks. The secret of a good join is the combination of a glue and a
mechanical fixing. A nail on it's own will hold the joint, but will move if stressed. Glue on it's own will hold
but if it breaks the whole issue falls apart. Glue and nails work in concert. The nails mitigate any stress on
the glue bond and the glue stops any movement.

Some glues are brittle. The fast-setting two-part Epoxy is strong but very brittle when cured. The slower (2hr)
setting stuff is much tougher. Both need to be clamped while curing or the joint can actually be forced apart.
Same applies to Polyurethane glue. Very strong but very user-unfriendly.

A glue joint needs pressure to get a good bond. Pressure will force the glue into the wood somewhat and
ensure that the maximum area is fixed firmly.

I have on occasion had to break frames apart, so the opportunity to test joins arises. I did one once that had
an very chunky moulding. It was basically a bit of 4x2 with a few bits milled off. I got it on sp offer, otherwise
I would have avoided it. o_O. I used two biscuit slots, glued the whole thing up and cinched it up with a webbing
strap. While clamped I put two 4" woodscrews across each corner. Way too big to underpin. It joined well after
a bit of persuasion, but unfortunately one rail must have been warped so a corner was a misaligned. Tried a bit
on judicious sanding to try and disguise it but couldn't quite manage it. So I tried to break it down. Even with my
huge strength I couldn't break it. :confused: Had to take saw to it.
The moral is: Large glue area + pressure on the join + solid mechanical fittings = Strong Join. :D
 
Just an observation. I was out of "wood" glue at some point and grabbed the fabric glue (Mighty Muck). It worked like a charm. 1.5" X .75" profile in soft wood, 2 v-nails. This was for a job due out in a couple weeks, so the frame sat.
When I go to fit, I discover I cut the frame 1" too big on one side. No problem, just back out the v-nails, break the glue joints, and trim the rails, right? Wrong. I could not break the glue joints and was probably going to ruin the frame trying. Ended up sawing the frame apart and recutting the miters. If it had been Titebond, Corner weld, Maxim or Elmer's Carpenter glue, I could have broken the glue joint.

That's a pretty fancy rig there Jim. I use band clamps* for gluing up floater frames. About the only time I glue and let it cure before putting in any metal. I use the Hoffmann whenever possible, but we've been using the 1/4" floaters mostly.

*Corner shims may be necessary since the articulating clamp faces put the pressure inside of the miter causing the miter to open on the back on thin profiles.
 
wpfay said:
...I could not break the glue joints and was probably going to ruin the frame trying.
Click to expand...
That's why I mentioned that CornerWeld allows you to take the frame apart if needed.
:cool: Rick

P.S. One thing I've noticed about the black maxim glue is that it thickens up in the bottle and in the dispenser tip. This can be a big frustration and time-waster.
 
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