# I think heat from belt sanding made my glue joint come apart.



## Jimothy (Oct 29, 2015)

So I glued up some wenge/birch panels together, and I left them for about 2 hours. I know I know I should wait 24 hours, but in my experience it's always been long enough to at least sand them, I didn't need to plane them because they were already quite flush. I was using 80 grit on a belt sander and it was producing some heat as per usual, but definitely wasn't burning the wood, which has happened to me before from putting too much downward pressure. After some time, only one of the glue joints came apart and it seemed like it almost melted the glue or something. It was strange looking, it didn't look like how uncured glue usually looks.

Is it possible the heat melted the glue joint? Has anyone else had similar experiences? Maybe if it was fully cured it would have been fine, but this has never happened to me before, and I've done this a handful of times. Also, it was brand new sandpaper if that makes a difference.


----------



## LittleBlackDuck (Feb 26, 2016)

It's old sandpaper that would tend to buff and therefore heat up (more).

You didn't mention the glue you used… with *Titebond*, I've often sanded after about 1 hour without issues… Did you put a paper in/on the sander?

You should not put unnecessary pressure on your sander and just let it do it's job… If you need pressure I thing you should drop a grit or two and work your way up. I think that anything above slightly warm is being overworked.


----------



## PeteStaehling (May 3, 2015)

If you did melt the glue you are probably taking way too heavy of a pass. Multiple lighter passes are the way to go. Speed of feed can be a factor as well. If you are heating up the wood much, I'd recommend rethinking your procedure. You really ought to be able to avoid heating up the wood much at all.

Oh, and yeah I too often run stuff through the sander without waiting long for it to dry. Never had a problem with that.


----------



## craftsman on the lake (Dec 27, 2008)

I've got two belt sanders. Never had glue come apart but I let it cure a long time. If your piece is fairly large, i.e. it covers the belt, it will generate a lot of heat. The larger the surface the less pressure you can put on it. You must have noticed some slowing down and straining of the unit too. When that happens let up. Takes longr but it has to be.


----------



## JackDuren (Oct 10, 2015)

You can pull them from clamps within an hour if clamped correctly. You should be able to work the joint in that time. Just don't stress the joint.

Why they popped apart u don't know.


----------



## RichT (Oct 14, 2016)

I've never had that happen. How old was the glue and which one did you use?


----------



## splintergroup (Jan 20, 2015)

Same w/me as to sanding after only a few hours (or even less) with a DS.

Heat does soften the glue up somewhat, but I've never had issues, even when the surface (cutting boards) gets quite warm to the touch.

Wenge is somewhat oily so lack of surface prep may have had some effect, but still something is amiss.


----------



## trsnider (Nov 23, 2012)

Klingspor said I had (very) old belts when I sent one in after the glue failed. They said the glue deteriorates over time and won't hold up against the heat.


----------



## pintodeluxe (Sep 12, 2010)

I think the Wenge is part of the issue here. I believe it needed 24 hour cure time.
I don't think sanding had much to do with the failure, just that it was a somewhat oily exotic wood that was handled too soon. I've used Wenge in combination with domestic hardwoods without issue, but as a matter of practice, always let glueups dry overnight.
It's one of the few legitimate excuses woodworkers have to take a break!

Good luck with it.


----------



## HokieKen (Apr 14, 2015)

> I think the Wenge is part of the issue here. I believe it needed 24 hour cure time.
> I don t think sanding had much to do with the failure, just that it was a somewhat oily exotic wood that was handled too soon. I ve used Wenge in combination with domestic hardwoods without issue, but as a matter of practice, always let glueups dry overnight.
> It s one of the few legitimate excuses woodworkers have to take a break!
> 
> ...


+1 I suspect your issue is the Wenge. Oily exotics can be hard to glue up effectively.


----------



## JackDuren (Oct 10, 2015)

Are you talking about the the belt sander belt breaking apart at the glue seam?

I thought you were saying the boards broke apart…


----------



## WoodenDreams (Aug 23, 2018)

You didn't mention if the glue joints were 'end grain to face' or 'end grain to edge' or 'edge to edge' or 'face to face'. Also using 60 grit or 80 grit on a belt sander, shortly after a glue-up, it can grab the wood, and be considered stressing the joint, before glue being cured. Verses using 150 or 180 grit use within a two hour period. Example, I've had 80 grit yank the wood out of my hand using my edge sander without a stop block.

I think there's a lot of woodworking try to take short cuts in time factor after a glue-up. Doesn't mean it's not wrong, They've been getting by with it. "Knock on wood". This time stress won.


----------



## LeeRoyMan (Feb 23, 2019)

I'm only making an assumption, but it's my theory that wood breaths, 
and Wenge is oily and dense and doesn't breath as well as others. 
Since glue needs air to dry I figure it takes longer for the glue to get it through the dense, oily wood.

I always swipe the joint with acetone or lacquer thinner then glue and clamp and leave it for a longer period of time depending what it is.

Like I say, just an assumption, could be totally wrong, but at any rate more clamp time if nothing else.


----------



## RichT (Oct 14, 2016)

> I m only making an assumption, but it s my theory that wood breaths,
> 
> - LeeRoyMan


Tell me about it. My nightstand has COPD and keeps me awake at night with its wheezing.


----------



## LeeRoyMan (Feb 23, 2019)

> I m only making an assumption, but it s my theory that wood breaths,
> 
> - LeeRoyMan
> 
> ...


Well, if you can't dazzle them with brilliance, you have to baffle them with bull********************…....


----------



## Sark (May 31, 2017)

I also think that Wenge is the most likely culprit. A modest amount of heat with glue that's not sticking properly and you see the results. What glue should you use? Non-water-based glues, and that would include polyurethanes, epoxies and maybe cyanoacrylates. Also as mentioned, since wenge is an oily wood, the joint needs to be wiped down with a solvent such as acetone or lacquer thinner prior to glue up.


----------



## Sark (May 31, 2017)

Duplicate


----------



## Lazyman (Aug 8, 2014)

The oily wood may be a factor but also check the age of your glue, especially if it is Titebond. TB seems especially prone to failing when the glue is over a year old in my experience. So much so that I avoid it unless I need one of their special purpose glues, which is rare. When the TB glue was too old, it definitely had a weird consistency. Somewhere on LJ there are a couple of threads that have the key for deciphering the code date printed on the TB bottles.

On the other hand, the gallon of Elmer's Wood glue I bought over 5 years ago still works fine and still has the original consistency.


----------



## Jimothy (Oct 29, 2015)

Wow thanks for all the replies! I'll try and address all your posts at once, sorry if I miss something. The glue was brand new Lepage white glue, which I am quite familiar with. The joint was side grain to side grain. Now that I think of it, it could be the wenge considering it is known to be harder to glue and may take longer to dry properly. But that doesn't explain why only one joint came apart and not all the others considering they're all wenge to birch side grain to side grain. I usually do wipe down with acetone for exotics but in my experience I've never had to with wenge before, guess I should next time.


----------



## CWWoodworking (Nov 28, 2017)

Wait longer. I did something like you did and while my piece didn't come apart, it caused problems in the finish process. Ended up having to reglue top.


----------



## farmfromkansas (Jun 16, 2019)

If titebond were to go bad, would probably be the result of freezing. Titebond and Elmers wood glue are about the same product.


----------



## Lazyman (Aug 8, 2014)

> If titebond were to go bad, would probably be the result of freezing. Titebond and Elmers wood glue are about the same product.
> 
> - farmfromkansas


Not if you ask Titebond. Plus, the glues just feel different. No freezing in my heated shop.


----------



## homestd (Sep 10, 2018)

Just as a general procedure, I always allow 24hrs minimum in clamps for any glue-up. Regardless of material or type of glue. I just work on a different part of the project or clean the shop…etc. But then I'm old and no longer in a hurry to get it done.


----------

