Opinions Wanted About glues, underpinning, and hot glue tech for joining

[KingstonJW]

I currently join with a pneumatic underpinner plus CORNERWELD all-purpose wood glue. Another framer I collaborate with has recently been exploring three other glues and he recommended I give Maxim 15/5 a try. I am over simplifying but in this case he was using Maxim to join all 4 corners first with a pony strap holding everything in place, and then followed through with an underpin after it sets. (I did notice an old string here in the forum that briefly compares the two but I didn't find anything I thought was conclusive about the matter). Cornerweld seems adequate but I am not adverse to changing if there is a real difference.

Taking the discussion to the next level, I spoke with a Seattle area moulding distributor about the different glues and she indicated there is a hot glue technology in the home improvement market that is so good it may eliminate the need for an underpinner (gasp ). Initial cost of the gun about $150. She said her production staff have begun using it on some large volume jobs and small ready made frames with good results - no underpinning required. She hasn't sent me the photograph of the gun yet, or the glue manufacturer details... so I thought I would offer the topic for discussion here.

Does anyone have any firm thoughts about glue varieties for joining, or in particular have experience to share about hot glue alone for joining?

 

[Susan May]

You will probably get all sorts of answers to this. That being said, here are my two cents.

When you join a frame with glue and an underpinner, the v-nails hold the frame while the glue dries, and the glue is the actual strength of the join. If the frame falls off the wall, or in transit, the v-nails help hold the frame together if the glue joint breaks. But, if you join a frame with one of those new forms of hot glue that will not break... even if you stand on the joint, you run the risk of damage to the artwork inside the frame.

When things fall, something has to take the force of the fall. This is why we use hinging paper weaker than the paper we are hinging. You want the hinge to rip, not the art. Same goes for the frame. You want the frame to take the force of the fall, and allow the inside package to remain intact. It's simple physics.

 

[Artrageous]

I've been joining frames with an underpinner and corner weld glue for 25+ years. I'd say it's been a successful way of putting frames together.

Although the key to a good join is the use of glue, I wouldn't skip using the underpinner. The vnails hold the join while the glue completely sets.

 

[Prospero]

Glue and pins work in concert. Glue on it's own is strong, but it either holds or completely fails. No middle ground. Pins on their own are strong, but they will give a bit, so they will need a lot of force to separate the join completely. But on their own, torsion will cause the joint to gap slightly. Together, they form a good joint because the pins squeeze the joint together while the glue sets. They act like internal clamps. Once the glue has set, the pins have served their purpose as regards clamping bit, but continue to protect the glue line from trauma and act as a fail-safe.

I know some folks clamp a frame up and then add pins when the glue has set. This is something I would try to avoid. Can't see the point of it. Putting pins into a joint is quite a violent process and might even threaten the integrity of the dried glue bond. I do sometimes (on big frames) clamp all four corners with a strap clamp and then underpin. But I work fast and get the pins in before the glue sets up.

Just my fourpen'th.

 

[Jim Miller]

...he recommended I give Maxim 15/5 a try.

Maxim Glue for 5 minute setup/15 minute drying (red label) has been discontinued. The more-popular Maxim Glue for 1 minute setup/15 minute drying (blue label) is my preference, anyway, because its timing fits my joining procedures better than any of the other popular glues.

... she indicated there is a hot glue technology in the home improvement market that is so good it may eliminate the need for an underpinner...

Others have already explained the benefit of using glue with mechanical fasteners. There is no glue that would be suitable by itself for joining mitered frame corners, because in a properly-joined corner, even using the strongest-possible glue, the glued wood fibers could separate from one another under extreme stress, and that would usually be the point of failure. That is, in a properly-joined corner, the wood fails, not the glue.

Any of the popular wood glues used for joining frame miters would provide a strong bond if used correctly. So, if you are experiencing bond failures, examine your joining procedures. Changing glue brands probably would not solve the problem.

Here are some essentials to remember:
Make sure the miters are perfectly cut. Remove all sawdust and make sure there is no cutting oil, skin oil, color marker, or other contamination on the miter surfaces. Apply glue to the entire surface area of a miter, in suffcient thickness to avoid "starving" the joint", as the glue's moisture soaks into some woods more than others. (It's OK to use more glue than necessary. If it oozes out, wipe it off or use a moist toothbrush to remove it from crevices.) Securely clamp the corner immediately after applying the glue, either by installing fasteners or using a vice. Make sure the joined surfaces do not move during the setup/drying period of time.




I am a small-shop framer, a user of wood glues, and a consultant to Frame Specialties.

 

[Jim Miller]

About V-nailing...

If your v-nailed corners are not securely bonded, check to be sure the miters are tightly joined. If the underpinning machine is properly set up, the miters would fit together tightly and there would be no movement of those two pieces of wood during insertion of the fasteners. If any movement occurs - twisting, tilting, pop-up, etc. - then the glued/fastened joint would be weakened.

Setting up the underpinner correctly is essential to achieving good results. And that is a very common problem, since many framers either do not know how to set up their machines correctly, or do not realize the importance of doing it right.

 

[Rick Granick]

...make sure there is no cutting oil, skin oil, color marker, or other contamination on the miter surfaces.

Are you saying that a small application of colored marker to neutralize the color of bright gesso would weaken the glue join? I have always used markers or colored pencils to coordinate the edges with the frame's finish on patterns that would result in visible gesso at the miters because of carved or molded shapes, etc. I find that doing so minimizes the need to touch up these areas after joining, which might be riskier to complex finishes. I join using v-nails and CornerWeld glue.
:kaffeetrinker_2: Rick

 

[Baer Charlton]

Are you saying that a small application of colored marker to neutralize the color of bright gesso would weaken the glue join? I have always used markers or colored pencils to coordinate the edges with the frame's finish on patterns that would result in visible gesso at the miters because of carved or molded shapes, etc. I find that doing so minimizes the need to touch up these areas after joining, which might be riskier to complex finishes. I join using v-nails and CornerWeld glue.
:kaffeetrinker_2: Rick

Yeah Rick, we've all been doing it wrong for 40 years now.

And the glue we used for the first 80 years of the 20th century also doesn't work.

Corner Weld, Adam's Adhesive, Elmer's Milk, Tight Joint, and even the hot glue that several
people tried and found more than lacking..... are all ALTERNATIVES.

Just as a V-nailer by any brand name is an alternative to nailing.

All of this is an alternative to hide glue with hand cut pegs, dove-tails, bow-ties, and splines....

You all talk about saving time (5 minute set up is no good... so just the 1 minute...) and yet
you will futz with a roached mat, or sew for hours what can be done in minutes with an
tagging gun.
And don't get me started about hours spent on the Grumble..... because we don't talk religion here. :kaffeetrinker_2:

 

[jim_p]

Maxim Glue for 5 minute setup/15 minute drying (red label) has been discontinued.

Oh no! When was it discontinued? I don't use it a lot, but sometimes if I have a tricky moulding I'll glue it up in a band clamp, then v-nail it. I prefer the 5/15 for this application because of the extra working time. Guess I oughta call around and see who might still have it...

 

[KingstonJW]

Thanks for the discussion

As always, I appreciate disparate views and discussion in even what might seem a mundane topic. The bottom line seems to be that there aren't any real significant differences to the major glue brands and choice is probably a matter of price and workflow (Maxim comment). So my CornerWeld is apparently still adequate for the times.

I didn't see anyone here that actually considered a "glue only" technology as worth trying. I believe it was Sue who cautioned the need for give in a joint in order to protect the art.

I'll likely try to talk with the distributer who is using hot glue directly and see what their decision process was. When I learn it, I will come back and share.

I trust everyone to have a very good week.

 

[Jim Miller]

Are you saying that a small application of colored marker to neutralize the color of bright gesso would weaken the glue join?

Small application, no problem. We all use color markers on the edges, at least occasionally, for the reasons you mentioned. But yes, the glue bond would be weakened in whatever area is covered by the oil/solvent of that color marker. So, limit the colored area to just the edges and avoid getting it on the surface to be glued.

I once had a problem with corners joined by a new employee breaking loose very easily. She claimed to be an experienced framer, but we quickly discovered she was coloring the entire surface of the miters. No kidding.

 

[Jim Miller]

So my CornerWeld is apparently still adequate for the times.

Cornerweld, Maxim, TiteBond and other popular wood glues will all make strong bonds when they are used correctly. The hot glue might make a very strong bond, as well. Maybe polyurethane (Gorilla Glue) would make the strongest bond, but its foaming action makes it unpredictable and impractical for joining frame corners.

I didn't see anyone here that actually considered a "glue only" technology as worth trying.

Right, because no matter how strong the glue may be, the wood fibers around the glue could break/separate in the event of severe impact. Only sturdy mechanical fasteners, such as brads, v-nails, dowels, dovetails, etc. can prevent catastrophic failure of the joint.

 

[Rick Granick]

...she was coloring the entire surface of the miters. No kidding.

I guess you can't be too careful. You never know who might peek inside the miter someday.
Rick

"Maybe she had stock in the marker company." We always say the same thing about the young baggers at the grocery store who try to use a separate bag for every couple of items.

 

[David Hewitt]

On multi angle frames I will glue & clamp. When dry I will install a v-nail for liability.
Last week a customer brought in 2oo ft. of moulding he had made from old heart pine wood flooring. The profile he made would not cooperate with the underpinner, clamping, or vise.
The solution was to use the underpinner. We made a support for the rabbet. Made a mold by filling the cavity between the frame & underpinner with bondo & capped with 1/4 plexi so the moulding could be seen. then proceeded to join. It worked great.
Favorite glue-Cornerweld

 

[Prospero]

In my exp, glues that cure fast tend to be more brittle than slower ones. Particularly true of epoxy type stuff. And some glues can 'wriggle' a bit when setting and can blow a joint apart - even with v-nails in. I tried PU glue once. No doubt it's strong stuff and when set it is still slightly flexible. Which is a good thing on the whole. But I found it a pain to work with. It's messy. You have to clean off any ooze very carefully as it's not easy to remove afterwards. It's not cheap. And the shelf life once opened is very short. I got a pump cartridge of the stuff and used a little bit. Next time I went to use it it had set solid in the cartridge right though. I had a 6" long candle.