Glue...

[Susan May]

On another thread, the question was asked, "How much glue should you use, and can you use too much?". In all honesty, that question needed a different style of mounting. BUT, the question is a good one.

Glue:

You can use too much, and you can use too little. Plus you can use it wrong. In order to use glue for any purpose, you need to know what you are gluing together, and what kind of glue is appropriate to use. Just because a glue says it "Can" be used on something, does not mean it is the right glue for the job.

Elmer's white glue: Dries brittle, and is not reversible. Personally, the only thing I would use it for is watered down for paper Mache'.

Elmer's wood glue: Dries yellow, cleans up with water. I find it a decent glue for wood. Repairing chairs, and things like that..

Hot Glue: There are a few different types of Hot glue. I can give you more reasons not to use it, than to use it. It leaves strings of glue like a spider web all over your project. It can soften and let go if in a hot area... like a hot car, or on a front door, or even under stage lights. It does not hold well on smooth surface items like metal and can melt some plastics. Pros: It holds quickly.

Silicone Glue: Dries flexible. Safe (for fish and us)... AFTER IT CURES. But it takes a while to cure, so you must allow it to fully cure. If not fully cured, the off-gassing is nasty. Can be built up for 3D effect. As for artwork, it can be peeled off of metal items with no damage other than removing tarnish. (As far as I know.) BUT, it is not recommended for items with value.

Spray glue: Personally, I don't see anything good about spray glue... but that is my personal opinion. As for the Cons: Messy, hard to maintain an even amount applied, unhealthy to breathe, not know for a strong hold.





(Please add to my list, as I am writing this off the top of my head.)

As for using glue.

On wood, there are different ways of using glue. Typically, a woodworker will spread a thin amount of glue on both surfaces being glued. Allow the glue to mostly dry (And soak into the wood) and then add another thin layer of glue and clamp the two pieces together. The fist application of glue is to open the pores of the wood, and soak into the grain. The second layer of glue is actually gluing the two layers of glue together... not the wood. If you use too much glue, not only do you get a mess of glue gushing out of the join, you get a weak joint. On the other hand, too little glue, and you won't get a strong join either.

When gluing paper, (which we shouldn't normally do in a frame shop) too much glue can make things bubble, or ripple. To little glue will result in a weak join.


All glues/adhesives have their places, but just because it looks easy, does not mean it is right. Also, almost all glues have a learning curve. With any glue, too much is just as bad as too little. Your job is to find the happy medium.

 

[Grey Owl]

(Please add to my list, as I am writing this off the top of my head.)

As for using glue.

On wood, there are different ways of using glue. Typically, a woodworker will spread a thin amount of glue on both surfaces being glued. Allow the glue to mostly dry (And soak into the wood) and then add another thin layer of glue and clamp the two pieces together. The fist application of glue is to open the pores of the wood, and soak into the grain. The second layer of glue is actually gluing the two layers of glue together... not the wood. If you use too much glue, not only do you get a mess of glue gushing out of the join, you get a weak joint. On the other hand, too little glue, and you won't get a strong join either.

.

Hi Susan.

I had initially learned to do this method. Then I heard from someone (a woodworker, conservationist, ??? I don't remember who) that you should not add a second thin coat, because you are really just gluing glue instead of wood. Instead just glue once. So I now just put the glue on, then clamp.

Does anyone else remember this discussion?

 

[tedh]

I remember the discussion. On HitchHikers. I was so intrigued I called a technical rep from Elmers (or Lepage's up here). I was told that, when gluing hardwood, to thin the glue to half-consistency with water, apply a thin coat to both edges, let dry, then apply a normal amount just prior to glue-up.

 

[wpfay]

Russ, I think the technique changed with the changes in glues. The newer white glues (Maxim, Corner Weld, etc.) used for joining frames don't need the glue/clamp/open and re-glue/clamp again method that was used with the yellow carpenter's glues. The yellow glues penetrated the fiber of the wood more aggressively with a longer open time and additional glue at the interface was needed. The newer glues set much more quickly and have shallower penetration. At least that's the story I was told by a woodworker friend.

Other glues used in joinery include Hyde glues, both natural (granular reconstituted with water and heat) and modified (liquid at room temperature, no prep necessary), and two part epoxies such as Resorcinol used on exotics with high oil content (lubricious).

 

[Prospero]

I think it depends on the wood. Most mouldings use quite open pore woods which 'drink' the glue in well. I use PVA on the majority. Some woods such as oak can have an almost glass-like surface on the cut face so this type of glue doesn't penetrate as well. I have been known to drill tiny holes in an attempt to provide a better 'key'. Epoxy and Polyurethane are probably better for harder woods. The epoxy should be the slow-setting type, not the instant as the former remains slightly flexible when cured. Not to mention the extra jiggling time. A note of caution with these glues. They can move about as they cure and unless you clamp them very firmly - more than vnails, they can elbow a tight joint apart. Polyurethane also has a very short shelf life once you open a tube.

I'm not really convinced about the pre-drying method. Surely even a thing coat of glue will turn your plane-smooth miter into a slightly uneven surface. I was always taught that it's bad practice to glue on top of old glue.

 

[Susan May]

My point has been made.

Different glues require different techniques, and the person using them should learn the what and how of glue before attempting to do something that might damage something.
(Personally, I never did the thin layer of glue before gluing the two frame sides together. I always used Corner Weld.)

Wheat paste/ Gorilla Glue/ Glue sticks /Wall Paper adhesive/ Rubber Cement/ etc... These are all forms of glue that have specific uses, and specific techniques. Some glues like Rubber Cement have different uses depending on the technique. Never fear asking how much glue you should use. (Or IF glue is the right technique.)

 

[Joe B]

Hi Susan.

I had initially learned to do this method. Then I heard from someone (a woodworker, conservationist, ??? I don't remember who) that you should not add a second thin coat, because you are really just gluing glue instead of wood. Instead just glue once. So I now just put the glue on, then clamp.

Does anyone else remember this discussion?

Hi Russ, I believe I remember the conversation on the Grumble too. If I'm not mistaken, I believe it was Jim Miller that stated you should glue only once and that he too use to "pre-glue" then re-glue before joining. I believe he stated he was informed by a woodworker that pre-gluing was not as good as gluing just once because then you are just gluing glue. Jim knows his stuff so I tend to listen.

I also spoke to a cabinet maker shortly after I got into picture framing who told me to glue both sides of the mitre to make the joint the strongest. I tried that but found no difference between gluing 1 side versus 2 sides. I now just glue 1 side with a full thin smooth layer of Corner Weld that I apply with a Q tip. If I ever have to break apart a joint usually chunks of wood from the mitre will break off with the glue.

Joe B