Glue 101

[Dewald Swanepoel]

PVA glue, epoxy, hide glue, polyurethane glue, urea-formaldehyde, cyanoacrylate...

WOW! There seem to be so many different types of glue that people use and I'd really appreciate if someone could distil the topic and give me a bit of a 101 on glue. What are the differences and which applications should you use the various types for?
 
I've always used ordinary cold glue (which I believe is PVA glue). I'm starting to think now that the name "cold glue" is not even an internationally recognised name and that it might be a South African name for this glue? But it's the standard white wood glue of which you can wipe the excess off with a damp cloth.

Recently though, someone suggested I use aliphatic glue which looks very similar and is sold in very similar bottles but it has a yellowish colour and the word "professional" added to the label. I'd like to know what the difference between these two is. Why would you choose one over the other? Why does one exist if the other one does the same thing?

 

But really, I'd love to understand what all these other glues are all about and when one would choose to use which.

[TerryMcK]

I tend to use glues from Franklin International. They go under the tradename of Titebond. Have a look at their website for details/explanations here and Titebond here. You should be able to pick it up in South Africa.

For tough outside use I use West Systems epoxy or Titebond 3 if I don't have any epoxy left.

[Dewald Swanepoel]

Thanks Terry. I must be honest though, the Titebond website doesn't really simplify the matter for me. There's a video on the page that supposedly explains the difference between Titebond Original, Titebond II and Titebond III, but it only does so half way. It's full of sales talk and how this glue has been around for 60 years - the typical stuff you'd expect from an infomercial and how Titebond Original is generally awesome. The guy then goes on to explain how Titebond II is water resistant and generally awesomer and after that he explains how Titebond III is water proof, can be used at lower ambient temperatures, has a longer open time and is generally awesomererest.

 

But why does Titebond Original still exist if Titebond III is such an amazing glue that's approved by the FDA for contact with food stuff and fully water proof? What can you do with Titebond Original that you cannot do with Titebond III?

 

And now we're basically just discussing different products of one brand. I'm interested to know the differences between different types of glue, regardless of who makes it. So all three of these Titebond products look like PVA glue to me but I'd like to know how that differs from urea-formaldehyde glue, polyurethane glue etc.

[4-Square]

http://www.amazon.com/Glue-Taunton-Woodworking-Resource-Library/dp/1561582220

[Gilgaron]

I don't know the deep answers to your questions, but in short, glue is a binder in a solvent.  The properties of the glue come from that.  So, PVA glue is liquid vinyl, and the reasons there are different kinds is that the additives to convey water resistance alter the tack, drying time, and so on.  Hide glue is animal protein, so like a human mummy, it will last as long as it can stay dry.  Epoxy essentially involves creating a chemical reaction in place to make a new material in the joint, which is why it is permanent.  Polyurethane gets into a lot of organic chemistry, with all sorts of different lengths used for different applications. 

 

Much like mortar or concrete, you just need a solid with the right properties suspended in a solvent that will evaporate, and then smear it where you want it and let it cure.  What its final properties are depends on those ingredients and bridges many disciplines from science and engineering. 

[TerryMcK]

One thing you may notice is that the glues go up in price from I to III - each have their own applications but if you wanted to stick with one type then go with III.

 

Here is some blurb:

Titebond Original Wood Glue 

The best glue we have used with biscuit joints, providing strong initial tack with fast setting time to help minimise clamping time. This aliphatic resin is becoming very popular with joiners, carpenters and cabinetmakers alike. Excess glue can be easily cleaned off with just a damp rag!

 

Titebond II Dark Wood Glue PVA

Titebond II Dark Wood Glue is a dyed version of Titebond II Wood Glue. It provides a strong initial tack and fast speed of set to reduce clamp time. It also develops a bond stronger than the wood itself, offers excellent sandability and is unaffected by finishes. Titebond Dark is ideal for wood, hardboard, particleboard, leather, cloth and most other porous materials. Titebond Dark is easy to use, non-toxic and cleans up with water.

 

Titebond III Ultimate Wood Glue 

From Franklin of USA, described as an APP (Advanced Proprietary Polymer), Titebond III has been formulated as a dedicated wood glue to give you the ease of application of aliphatic/PVAs and the water resistance of polyurethane glues. Making an exceptionally strong bond on wood-to-wood joints, it has longer open time and higher viscosity than conventional PVAs and will maintain integrity at lower application temperatures. All of which makes for easier and less fraught assembly procedures. Polyurethane glue has undoubted flexibility of use and massive strength but is a very persistent adhesive, difficult to clean up from equipment and particularly hands. Titebond III has been designed to give you the strength of wood-to-wood bonds without the problems. It cleans up with water whilst wet, sands off without softening when fully cured, is unaffected by finishes, solvent and heat and is mildew resistant. It is suitable for interior and exterior use.

 

Titebond Polyurethane Glue

A professional strength waterproof glue specially formulated for multi-purpose applications. In addition to its superior wood-to-wood performance, it is equally effective for metal, ceramic, plastic, Corian® stone and other porous/non-porous materials. Titebond Polyurethane is ready to use, offers excellent sandability and is unaffected by finishes. Twice as thick as traditional polyurethanes it provides a non-running, non-drip glue line for more precise applications. Titebond Polyurethane will not become brittle with age and will not expand or contract in the glue joint. Polyurethane glues cure by moisture and an effervescence is a by-product of this, there is no strength in this and it is easily sanded off when dry. In very dry timber it may be necessary to moisten one surface to encourage curing to take place.

 

These Titebond wood glues have been independently tested for lead, cadmium and other metals under ASTM F963 and 16 CFR 1303 (total lead content). These are the testing methods specified for toy safety under the U.S. Consumer Product Safety Commission. It has also reviewed by an independent toxicologist and conforms to ASTM D4236 for art and craft materials.

[wouldwurker]

I'm not crazy about their numbering system.  I would assume that most folks see I, II, and III at the big box and think "good, better, best". 

So far, my most common differentiator between using Titebond I, II, and III is open time. 

 

Titebond I is my go to glue for jigs, crafts,  or any single joint glue up that won't be immediately be followed by say, the opposite leg.  Also exacto-knife overlay marquetry (watered down a tad).  I want an immediate bond.

 

I learned by lesson the hard way with open time and Titebond I....While using 50mm dominos, by the time I walked over to get my mallet to bring them flush, the dominos swelled halfway in the mortise and the glue set.  I had no clamps to pull the pieces flush and literally had to rip the thing apart.

 

I use Titebond II when I need time to shift and pound several things around (e.g. all four corners of a mitred box, extra time to add lots of clamps or cauls).

 

Titebond III for a 30m plus major glue up process with several counteracting joints.  Especially when I make a MISTAKE and need to separate the first joint 45 minutes after I glued it in!

[David Stephens]

Hey Deefstes,

 

Here in Germany we have cold glue as well.  The numbering system they use here is the D1-D4.  Maybe it's universal...?  I don't know why it's called cold glue, but the D-ranking means 4 is the strongest.

I use Titebond I and D3/D4 (cold glue) for everything.

Plus, I can get a 12kg tub of the cold glue for 45€.  Much cheaper than Titebond!

 

Most people say "if the joint is made right, most glues will work just fine."

I'll agree with that.

[wouldwurker]

Then again, I think I recall Marc in a video mentioning that William Ng only uses Elmer's Wood Glue.....so there's that

[Orbb]

Here is a good article from Bob Smalser

 

http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=smalser&file=articles_737.shtml

[h3nry]

Different glues have different properties, and you select the glue depending on the properties you need in your glue-up.

 

I'm certainly no expert, but here's how I use different glues:

 

PVA glue.

This is my general purpose wood glue and it does 98% of all my glueing. As mentioned there are subtle changes in water resistance, colour and open time in the different products. I generally only have one bottle on the shelf at a time, and so experiment between different brands - the biggest difference seems to be in the open time, but they are all in the minutes range. What makes PVA glue so good for woodworking is that it makes a very strong joint between two bits of wood with an open time that fits most glue-up tasks.

 

I'll only choose a different type of glue if there is something special about the glue-up.

 

Epoxy.

The three things that make epoxy great in my mind are a) long open time - sometimes it's hours (this can be a pain if you actually want to get back to work on your project that day).  b.) Weather resistance - epoxy is basically a plastic and pretty impervious to water, plywood boats are coated with epoxy and then spend their lives in the water. c) Gap filling - expoxy takes up volume, this is good if your joint isn't a perfect tight fit and has some gaps that need filling, or for stabilizing knots and checks.  But as a general purpose glue, It's toxic, messy, slow to cure and expensive.

 

CA glue:

I'm not a big user of CA glue, but I do use it for glueing chips back onto a piece that I clumsily broke off. For this it is great - It cures almost instantly, with a very thin glue line. I think it's the instant bond time that makes it most useful in places that are hard to clamp.

 

Hide Glue:

Hide glue's biggest selling point is that it is reversible. If you ever want your joint to be unglued then you probably want to use hide glue. Musical instruments are often glued with hide glue so that they can be opened up and repaired if necessary. One of the down sides is that it can come unglued with too much heat and humidity.

There are two types on hide glue: hot-hide glue and liquid hide glue, and they have very different open times. The liquid hide glue has fairly long open time (minutes), but the hot hide glue has a short open time (seconds) this has the advantage of not requiring clamps. I only use hot-hide glue, and I only use it for veneering and marquetry where I like that short open time. It's too messy and smelly and a kerfuffle keeping the glue-pot at the right temperature and viscosity for everyday use. I've never tried the liquid hide glue.

 

There are other properties like flexibility, and how they affect finishes that could be important, but I don't usually think about these until after it's too late.

[Dewald Swanepoel]

Fantastic answer H3nry. Thanks for that.

[Dewald Swanepoel]

Here's an interesting article published in Fine Woodworking some years ago doing failure tests on different types of glues on different types of wood. I thought someone else might also find it interesting.

http://www.oldbrownglue.com/images/articles/HowStrongisYourGlue_FWW.pdf