Edge gluing with epoxy didn't work so well

[jeff...]

Well I figured I would give epoxy / sawdust mix a try. I edge glued three white oaks boards together. One of the edge glued joints failed and also 1" band I glued to the endgrain.

I'm sure it was something I did wrong. I mixed up appox equal parts resin / hardner / fine saw dust from my belt sander. Did I use to much saw dust or should I have used a differnt kind of epoxy? It was Loctite 5 min epoxy like this one 5-Minute Epoxy Syringe
I had good squeeze out from the joints, so I'm confident I used enough.

Advise from the experts would be greatly apprciated.

No worries, I'll resaw the joints and re-glue with good ole yellow glue - I know that will hold.

Thanks

 

[SteveColes]

Jeff, I'm not why you wanted to edge glue with epoxy and filler.

Anyway, here are a couple of quick points.

One quick cure epoxy is not a very good idea for most woodworking applications. The epoxy tends to "go off" before you can mix, apply and clamp. Once you feel any heat from the mixture, You are done. it is too late to do much more.

The more filler you add to the mixture, the weaker the joint.

Epoxy and wood flour when cured DOES NOT take stain. It is best to add a compatible tint to the mixture to get as close as possible to the desired finished color.

When using epoxy for wood working, it is best to buy a formulation that is intended for woodworking. System 3 is one good example. It is what I use now. But when I was doing model ships, I used different formulation/ manufacturer (can't remember who)

Anyway, to sum up, I would suspect that the combination of quick setting expoxy and the filler caused your failure

Epoxy and wood flour makes a great filler, but a lousy adhesive.

 

[woodguy1975]

Jeff, you really need to use slow set epoxy. Slow setting gives the epoxy time to work into the wood fibers and anchor well. Fast setting is just too fast to get it on the wood and clamped together before setting. Also epoxy doesn't require a lot of pressure like yellow glue. Just need to close the joint and stop. BTW, 1/3 filler (sawdust)is way too much. I typically use about 10% of 320 grit dust. Belt sander dust is way too course.

I wouldn't edge glue with epoxy anyways. I use PRG (plastic resin glue) primarily for edge gluing because of the lack of creep.

It was worth a shot anyways! You never know until you try.

John

 

[DavidF]

I would also stay away from epoxy for this type of application. If it needs to be more water resistent then use TB III or PRG as WG suggests. If it needs to be chemical resistent then use the epoxy, but with no filler and use the slow set.

 

[Howard Acheson]

Let my add one VERY IMPORTANT POINT. Unlike most woodworking adhesives, epoxy relies on a certain amount of film thickness to develope strength. You do not want to tightly clamp epoxy joints or the film thickness will be too thin and the joint will not hold. Only apply minimal pressure to keep the joint together.

I too, question why you want to use epoxy? And, why you want to use a sawdust mixed into the epoxy.

 

[woodguy1975]

Let my add one VERY IMPORTANT POINT. Unlike most woodworking adhesives, epoxy relies on a certain amount of film thickness to develope strength. You do not want to tightly clamp epoxy joints or the film thickness will be too thin and the joint will not hold. Only apply minimal pressure to keep the joint together.

I too, question why you want to use epoxy? And, why you want to use a sawdust mixed into the epoxy.

Howard,

I think Jeff was taking my joint gluing practice a step further. On my rockers I use epoxy with a little sawdust to tint the epoxy so if there are any gaps in the jointery it will be hidden. Works very well with walnut and mahogany. The seat joint on my rockers and chairs are such the epoxy gives great strength. Epoxy has much better strength where there may be gaps in the joint or where you have an end grain situation. On my table that is on the calander I used epoxy with black pigment and dowel to attach the blackwood feet to my legs.

 

[jeff...]

Well since many want to know "why" did you do that? :slap:. One reason only, I was experimenting. Never tried it before and figured it was worth a try, just to see how it worked. Next time I'll know to use slow set epoxy and about 1/10 sawdust instead of 1/3.

As Woodguy said "You never know until you try" I really like that kind of philosophy. I'll even take that a little further, mistakes aren't so bad, there darn good teachers.

Couple of good things I noticed:icon_thum:
* Yep it does gap fill sloppy joints. I made a little mark with a razor blade on the edge of one of the boards and it filled it best part is you can't even notice it's there.

* I don't stain wood, so the dust colored the clear epoxy with a darn near perfect match, once I applied a clear finish to the surrounding wood.

* In my mind, Woodguy is a genius for thinking of this. Granted there's no substitute for a bad joint. My joints are far from perfect, but now they will look good. :-D


Thanks

 

[jeff...]

Ok - I'm feeling a little out of sorts here. Many are talking about using PRG (plastic resin glue). Ive been using good ole Elmers carpenters glue for a number of years. I've tried others like titebond, etc... but always seem to come back to good ole Elmer's. I don't think I've every used PRG before. What brand do you guys use or is there really no difference? Whats the pros and cons or the brand to buy?

I'm looking at Dap, it looks like it comes in a powder and you just add water Dap® Plastic Resin Glue - Adhesives - HeavyDutyStore.com . I really like the idea of powder and mix as needed. :icon_thum

More advise from the experts is needed, please :-D

Ever get the feeling you've been doing something wrong for years and not knowing it was wrong?


Thanks

 

[McRabbet]

You can get a 5 pound tub of urea resin glue from Woodworker's Supply for about $25 plus shipping. Woodguy uses it, too. Mixes with water, has great properties and a long pot life.

Rob

 

[Howard Acheson]

>> Ok - I'm feeling a little out of sorts here. Many are talking about using PRG (plastic resin glue).

Plastic Resin is a brand name of DAP/Weldwood for their urea formaldehyde (UF) adhesive. The full name is DAP/Weldwood Plastic Resin. It's a powder that you mix with water.

There are other UF's but those are two part chemical adhesives and are sold in commercial quantities and have limited distribution.

>>Ive been using good ole Elmers carpenters glue for a number of years. I've tried others like titebond, etc... but always seem to come back to good ole Elmer's.

Nothing wrong with Elmer's Carpenter Glue. It's a pretty standard PVA adhesive little different from others like Titebond. I prefer Elmers as it tends to be a little less drippy and seems to have a slighly higher tack. Like all PVA's, it does creep so I don't use it for edge to edge panel gluing. But PVA's are great for most other joints.

>> I don't think I've every used PRG before. What brand do you guys use or is there really no difference? Whats the pros and cons or the brand to buy?

See my response above.

 

[botebum]

Well, other than the thread to introduce myself, this will be my first post of any significance.
One very important point that has not been mentioned is that White Oak doesn't always do well with epoxy. Some have no trouble, some swear by it, most swear at it. Yellow glues or resourcinol are your best bets. Polyurathane glues(ie. Gorilla Glue) may work well, but I honestly have no experience with it. If waterproof is an issue- I'd go with resourcinol. If not- yellow glue.
Just my .02

Doug

 

[SteveColes]

Howard, which glue do you use for edge to edge panel gluing?

And here is a question, I'm almost ashamed to ask. What do you mean by creep?[

>> Ok - I'm feeling a little out of sorts here. Many are talking about using PRG (plastic resin glue).

Plastic Resin is a brand name of DAP/Weldwood for their urea formaldehyde (UF) adhesive. The full name is DAP/Weldwood Plastic Resin. It's a powder that you mix with water.

There are other UF's but those are two part chemical adhesives and are sold in commercial quantities and have limited distribution.

>>Ive been using good ole Elmers carpenters glue for a number of years. I've tried others like titebond, etc... but always seem to come back to good ole Elmer's.

Nothing wrong with Elmer's Carpenter Glue. It's a pretty standard PVA adhesive little different from others like Titebond. I prefer Elmers as it tends to be a little less drippy and seems to have a slighly higher tack. Like all PVA's, it does creep so I don't use it for edge to edge panel gluing. But PVA's are great for most other joints.

>> I don't think I've every used PRG before. What brand do you guys use or is there really no difference? Whats the pros and cons or the brand to buy?

See my response above.

 

[DaveO]

Steve, glue line creep is something that shows up long after you've glued and finished a panel or slab. It manifests itself as a slightly raised line at the joint, you can only feel it with your fingers. It is the result of different MC of the boards being glued up. Yes, it can even happen it the boards are ripped from one large board, the MC in the center might not be the same as on the edges. Basically you get different swelling and shrinking that results in pushing the glue line up just a bit.
I am sure that Howard or others can explain it much better :5dunce:

Dave

 

[Travis Porter]

You know, I have read about creep, but never experienced it in 15 years. I have read that the UF glues are better for gluing strips and all (like making curves), but I haven't done much of that and when I did I used yellow glue. I finally caught an episode of David Marks show this weekend, and low and behold, he was using it to glue I believe IIRC veeners together.

Now I have an inkling to get me some of this glue and give it a try. Unfortunately, my local HD doesn't carry it. I have seen it before, so I will have to go to one of the larger BORG's to see if they have it, or who knows, maybe go to Woodcraft or Klingspor.:eusa_thin