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Epoxy for wood

5K views 36 replies 17 participants last post by  stevekir 
#1 ·
I'm having to rebuild an exterior door frame that rotted on the lower end (long story, don't ask how). I've machined out the moulding to match and done the threshold. I need to glue a 2-1/2" ship-lap to add the new to the old. It's an exterior door and I'm thinking epoxy, but what I have on hand doesn't do wood. Any suggestions would be appreciated.
 
#3 ·
...but what I have on hand doesn't do wood
Wait, what? Is this like, an epoxy plumbers putty or something? Epoxy is one of those glues that really doesnt care what it gets stuck to, long as the surface is prepared properly it sticks. About the only exception to that that i know of is polyethylene/propylene, and nothing sticks to those.

Recommendations though, it really shouldnt matter, any decent 2 part epoxy will bond wood pretty well. As a general rule, the longer the glue takes to cure, the higher the strength is, so go with the slowest cure you can manage. The 15 and 30 minute cures are a good all-around choice, 5 minute epoxys cure to fast and arent strong enough in my opinion, and not everybody has the time for a 24 hour cure.

My personal favorite epoxy is West Systems G-Flex. Strongest crap ive ever used, a butt joint between some cocobolo and ebony that i did with 0 surface prep resulted in a joint that i had to lean on a pipe wrench to break. Downside is the 24 hour cure time. If you can stomach that though, the strength is insane and its surprisingly flexible, so seasonal movement wont break the joint
 
#8 ·
Is this a horizontal surface that will catch rain water?

If so, I'd use epoxy. Boatbuilders have used it for decades, never heard of TB3 being used on boats, at least below the waterline. Added benefit to epoxy is that it has gap filling properties so if pieces don't fit perfectly they will still be solidly joined and water tight, add some thickener as needed.
 
#12 ·
Most epoxys will penetrate most woods. How much they penetrate is a variable based on numerous factors, but they typically do penetrate nonetheless.

Boats, oars, paddles, wooden surfboards, etc. are all examples of just how effective epoxies can be when used on wood.

Most epoxy manufacturers now have what they refer to as "penetrating epoxy". Again, how much they truly penetrate is dependent upon a number of variables. West Systems and MAS are two that I've used extensively.
 
#14 ·
Either type of glue should work up to a point.The point where it doesn't work is if the piece you are attempting to glue moves across it's width and the fibres in contact with the glue pull away from the bulk of the piece.By selecting a quarter sawn piece you will reduce the risk of this happening.
 
#15 ·
To you general question Charlie...without knowing the conditions the door is subjected to on a regular basis, I can't really give a good definitive reply...or..."good recommendation."

You may not need an epoxy at all and only a good "all weather" adhesive (like Titebond III)...or...you may very well need an actual wood solidifying epoxy and thus also other targeted epoxy adhesives meant specifically for your given application like the line that Abatron (et al) produces?

Let me know if this is of value or if I can expand further on what I shared...Feel free to email directly as I only post on weekends here generally to avoid the constant "debating," on too many posts...
 
#16 ·
Hey all...Thanks to everyone, I didn't mean to start a ruckus. LOL


I'm going with the G-Flex. I've got a pretty good fit on the joints but I don't plan on repeating this operation...EVER! Just one question...what is best for cleaning up the epoxy squeeze so these joints are pretty? By the way, I'll post a couple of before and afters when Its done.
 
#17 ·
Youve got nothing to apologize for, you just stumbled into a bee hive... Really just boils down to authority and ego, but none of it is your fault

Good choice on the G-Flex, like i said its hands-down the best ive used, and shockingly theres next to no price premium on it. As far as cleanup of the squeeze-out goes, theres actually several methods you can use. The most obvious one is wiping it off with a solvent while its wet. Denatured alcohol and acetone both work well for this, but its a messy process. Ive hear tales that baby wipes do the job well, but i have more acetone on-hand than small children, so i cant vouch for that. You can also chip/sand the excess off after its cured, works but not my favorite method.

What i like doing, when the situation allows, is a bit of a compromise between the aforementioned methods, and will work for you if both the pieces are already pre-finished. First, dry assemble the joing, get everything looking how it will once the glueup is done, then wax the entire area. Dont get any wax where you want glue, of course, but get it everywhere that you dont want glue to end up. Once thats done, glue up as you would otherwise, but instead of walking away straight after, wait until the epoxy has gelled, bout an hour or so with the G-Flex. Then, come back and just pop off the squeeze out. No mess, no fuss, and the wax just buffs off afterwards. That said though, dont do this on unfinished pieces, the wax will prevent finishes from adhering!
 
#18 ·
Epoxy is the ideal material to make lasting fixes of spoiling window ledges, door frames and outside embellishment that are hard to expel and costly to supplant. Epoxy is anything but difficult to deal with as well. You blend it like treat batter, form it like demonstrating earth and, when it solidifies, you cut and sand it simply like wood. It sticks like insane and is defined to flex and move with the wood, so it won't split and drop out like some outside wood fillers.

There are many brands of epoxy the exact mixing and application procedures vary a bit depending upon the manufacturer you must follow the manufacturer's instruction carefully. :wink:
 
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#19 ·
So, if you are manufacturing a product and it's being returned by the customer because of the type adhesive used you are suppose to ignore it? Say people on the internet say it's the best and accept it? We were using an exterior PVA adhesive and it was working great and epoxy was suggested so we tried it. Then when parts started coming back we when back to PVA and that solved the problem.

Again, I've been around for a long time and post my experiences.
That doesn't prove anything beyond that type of epoxy not working in that particular application however many years ago. Maybe for that situation yeahz that epoxy was a bad choice because of low flexibility leading to broken glue joints or similar

The bottom line here is that presenting one, personal opinion as a solid fact is a fallacy, and a blanket statement like "epoxy isn't an appropriate glue for wood" is factually wrong to put it nicely. Does epoxy work everywhere? No. Neither do PVA adhesives.
 
#21 ·
We were just gluing narrow strips of ash and Honduras mahogany in a gentle curve to make tiller handles for boars. It maybe had a 3/4" bow in 4' and was enough pressure to cause the joints to fail.

Over the years I've had other failures with epoxy gluing it steel or other non-porous things. In hindsight I believe it has as much to do with wood movement as anything. Epoxy dries harder than PVA therefore more likely to crack. Sometimes you don't have a choice though. PVA won't bond to steel where epoxy will. It just makes sense that if you are gluing new wood to new wood you use a glue formulated for wood.
 
#22 ·
I don't know how many more different ways I can say this. The bickering simply has to stop. Honestly, NO ONE wants to hear it. We are all either part of the problem or we are part of the solution. It doesn't matter who said what. We can CHOOSE not to respond to the nonsense, report it, and then simply scroll past it all. If we engage in the bickering we are absolutely part of the issue.

We all have different opinions. That's real life.

Can you imagine how boring things would be if we all agreed on everything?

I encourage open discussions. It is how we all learn.

That being said, woodworking isn't an angry debate, even when we disagree.

When a member asks a question, the odds are very good that there will be a wide range of answers, some of which may be the complete opposite of what you believe. When we see a post (in the responses) that we don't agree with, it is not up to us to prove why their response is right or wrong, or why we think our response it better. Doing so will only confuse the original point of the discussion. Sometimes there is no right or wrong answer. It is up to the original poster to determine which response makes the most sense to them.

Treat each other with respect. :smile2:

Respect For Others In The Community

This thread will be closed while I clean up the nonsense.
 
#27 ·
jbweld also makes jbwood, it is a 2 part epoxy that works well outside
i have a laminated 6 foot radius deck rail that i built 18 years ago
it has needed a few repairs over the years mostly due to knots that cause rot/delamination
i repaired it a few times with waterproof fillers that failed within a year or 2
7 yrs ago i tried the jbwood, have yet to have a failure

i originally tried the twin tube pack for a few knot voids on top of the rail, it hasn't failed in 7 yrs
it is thin enough to flow into cracks



i ended up skim coating the top of the radius 5 yrs ago and used the bigger putty kit
it is a lot thicker and goes on like thick filler
still looks good



i'd use the twin tube for glue up and small filling, i used masking tape to contain the flow
the putty pack for bigger filling of rotted areas, just gouge out to good wood and fill
 
#36 ·
Would like to make 4 things clear

1. Epoxy is made from epoxy resins. Not all 2 component products are epoxies Must say "Epoxy"

2. Dont over tighten your clamps. Epoxy uses a moderate pressure not a complete cranking down.

3. Not all epoxy resins mix the same way. Some 3 to 1, some 5 to 1 , some 1 to 1.

4. There are also thickeners for epoxy. Some thickeners are designed to make the bond stronger and some are made to be sanded easily

Read the instructions
 
#37 · (Edited)
Squeezeout. I have solved the problem. There are two ways: before the mortices are cut, and after.


Before: I put some tape over the parts (both sides of the "line") where the blunt end of the mitre cut will appear - 8 pieces of tape for the four mitres. Then I cut the mitres as usual and with a little luck the tapes will remain but only right up to the blunt side of the cut, the rest of the tape having been cut away with the mitreing. That is all that is necessary. After assembly and waiting for a few minutes for the squeezeout to thicken a little, I remove both tapes, together, from each mitre. The squeezeout comes away with the tapes and leaves none behing.


After: I put some tape accurately on and along the blunt line of the mitre (not of course on the surface where the intended glue will go) - again 8 pieces. Then assemble the joint and as above, After assembly and waiting for a few minutes for the squeezeout to thicken a little, I remove both tapes, together, from each mitre. The squeezeout comes away with the tapes and leaves none behing.


These methods prevent even any glue contaminating where it shouldn't be, thus preventing trouble when staining the wood. Fiddly but effective.
 
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