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Differences between types of Titebond glue10/13
Sometime ago I recall reading a dissertation here about the differences between various types of titebond glue. As I recall it had something to do with hardness of glue line and glue lines telegraphing through finish.
We currently use both titebond 1 and titebond 2 in our shop though I am not really sure why. The titebond 2 has a pretty intense yellow dye that seemed to stain white plastic laminate so when we do this part we stick with the titebond 1.
If anybody can explain the various differences again I would appreciate it.
Franklin International has a pretty informative website with technical information on all their products as well as techs available by phone. I have been told verbally by a tech that Titebond 1 Extend has the most rigid glueline (read creep resistance) of all the Titebond products.
For what it's worth.
I'm a former Franklin employee and worked in the technical group until March of this year. Bill, your name sounds very familiar and I'm almost positive I've spoken with you at some point. If you're who I'm thinking of you requested an informational CD after IWF two years ago after talking with Dale.
Anyways, since departing Franklin I've founded a business that is focused on guitars (after consulting that industry for a bit over a decade.) I have no industry affiliations with respect to adhesives: So here's the straight dope on the differences:
White glues were the first PVA based adhesives and had little else to them. As a result they had lousy water resistance, were highly prone to creep, and generally wound up with a poor reputation compared to hot and liquid hide glues that were dominant in the woodworking industries at the time (mid 40s.) In order to improve their performance across the board (tack, creep resistance, thermal resistance, water resistance, to name a few) tackifying resins were added. In case you're wondering, this is all that "aliphatic resin" glues consist of. I often call them resin-modified PVA's because I consider it a less confusing term. This modification would not change the color on its own, so the decision was made to add yellow dye to differentiate them from white glues and is purely a marketing strategy. I have personally used dye free Titebond II and tested low quality yellow glues from manufacturers who have done nothing more than add dye to white glue. Uninformed individuals may try to convince you that yellow was added because it provided a better match to the surrounding wood. This is simply untrue. Not to mention, if you can see a glue line it's too thick. As part of some competitive testing I performed on Gorilla Wood Glue (not the polyurethane... The type II water resistant white glue) I found that not only was it nearly colorless and clear when dried but its performance was effectively identical to that of Titebond II. If you need something colorless for an exterior application I would not hesitate to recommend Gorilla Wood Glue. Titebond III is a different animal. It was actually the end result of a project to achieve type I water resistance from a PVA as a method to compete with urea-formaldehyde adhesives. It does accomplish it, but unless you're building a cutting board, countertop, or skateboard, I wouldn't recommend it. The product is prone to creep, and there's a reason its shear strength at 150°F isn't published: it's not great, usually around 1000 PSI which equates to a 2/3 loss of bond strength.
In terms of strength, at room temperature a good white glue can cause 100% wood failure just like Titebond Original, Extend, Titebond II, and Titebond III. Under ASTM D-905, they are also tested for shear strength at 150°F at which point from best to worst the list will look as follows: Titebond Extend, Titebond II Extend, Titebond Original, Titebond II, Titebond III. All PVA based adhesives are thermoplastics, which simply means they will melt (most of them reach their melting point somewhere above 250°F.) This is known as thermal plasticity, and in case you're wondering, it correlates exactly with creep resistance. It's also the reason that as a guitar manufacturer I personally use primarily Titebond Extend and Titebond 50. They're overkill, but if a guitar gets left in a hot car I can still feel confident that it wont come apart.
I've seen the term crosslinking a lot in this thread and some confusion about how it relates to creep. Picture plain PVA adhesive as wet spaghetti noodles: If you leave them to dry they will tangle around each other and shrink a bit, and you won't be able to pull the mass apart easily. Put that mess back into water and they will separate. Crosslinking PVAs would look more like spaghetti noodles that actually fused together as they dried and if you put them into water again those fused points (just like covalent crosslinks) would not separate. However, they do *not* crosslink with the wood itself. Instead, they have relatively weak electrostatic interactions (known as hydrogen bonds and van der waals forces) but in HUGE numbers, which is why they still create bonds stronger than wood.
I saw Bob's name mentioned, you're welcome to contact him if you wish. I helped train him, and unlike myself he comes from the sales/marketing world and still has an obvious corporate affiliation. In my case: I'm an entrepreneur with no specific allegiance to any adhesives company aside from my father who works for their industrial division. My Dad is the reason that despite being a younger guy I have been learning about the adhesives industry for over 25 years. I do my best to keep an eye on message boards because even though it's not technically my responsibility anymore, I care about getting good information out to fellow woodworkers. Not to mention, at over 5 months unemployed and just starting to get endorsements and contract work... It makes me feel like I'm still contributing something to the world.
I'm sure I've opened a can of worms, so feel free to reply or contact me directly. I'm always happy to help.
Thanks Kevin & Richard.
That was a fascinating read. Thanks for posting it.
Hugh mentioned the concept of "creep". I would like to make sure I understand this.
Several years ago we used to use a glue called Dorhus Express. It was a very thick white glue. We used it because it set up very quick. You didn't have to leave things in clamps very long at all.
The problem with this glue is you would clamp a piece of lumber that was perfectly aligned to a face of plywood. When you came back a few minutes later it would have slid a little bit and adjusted position.
Sometimes after we glue three sticks of lumber together and run it through the widebelt sander you can see a pronounced glue edge. The glue forms a little ridge and is slightly taller than the adjacent lumber.
What is this called & what causes it?
"and run it through the widebelt sander you can see a pronounced glue edge" Reasons: surfaces not perfectly prepared resulting in thick glue where they didn't meet tightly. Not long enough time elapsed for the glue to fully set hard. Not enough clamp pressure. Water absorbed from the glue is swelling the wood @ the joint, wait longer to machine.
I like gluing right off the straight line saw. I think the edge is more open and allows better bonding than joints that have been jointed.
Ca maker...the ridge is caused by the heat in sanding causing the glue to soften and then the pressure on the joint (after sanding) pushes a little of the adhesive out. Using fresh sandpaper, which has much less heating and reducing the amount of material removed (do not use a sander to do what a jointer or planer should do) will reduce the heat. You can also use an adhesive that is less prone to softening when heated...there are many different formulations of the PVA adhesives that are available.
Hmmm... So none of my thoughts on glue problems on glued up panels was it. Good aim Gene. Thanks always appreciate your input.