Question about joining finished woods


#1

Sometimes I want to join to identical pieces of wood that I’ve cut to thicken the project. So let’s say I have 2 or more pieces of freshly-cut thick maple ply. And I want to join them so it’s one piece of super-thick maple ply. I’ve used Gorilla glue, sparingly in the center-ish area and clamped them and returned to find them joined very well, but with glue squirted out the seems. If it’s not clear, I don’t know much about wood. I’m guessing it’s because these pieces are finished wood that’s nearly-perfectly flat so, when smashed together, the glue’s gotta go somewhere. So what’s a better answer? Different glue? Different technique? Both? I’ve thought about laser-scoring the woods before attempting to join them. (It’s like the only thing I recall from working with similar things in art class in grade school.) I haven’t tried that though, but it seems a reasonable technique.

Suggestions?

Thanks!


#2

I should think that any material with a finish on it would require abrading before any sort of bonding.
Even painted metal welds better if remove some paint.

I would say Sanding or Score would both aide the effort.

To avoid glue oozing out, I would suggest wiping the glue on with a brush, sponge, or rag, to avoid puddles.


#3

YMMV, but I’ve found less is more… Joining two finished surfaces will require less glue. I wipe of any excess once the clamps are in place with a damp rag (not a paper towel).

You might try some of the CA formulations, a few well-placed drops might work, depending on the application. Oh – If you’re using the “original” gorilla glue, it foams up in the presence of water (even humidity from the air) – their yellow wood glue formula does not.

Plus whatever Jules and the other experts recommend. :wink:


#4

Sometimes I do a light LPI engrave to give it some tooth if it’s not too large of an area, but mostly i just attack it with that weeding tool that i use for so many things around here.

Scratch it up real well, (nice for relieving tensions as well), and the parts don’t shift around as much when you clamp them.

Sixty grit sandpaper also works and is quick. (Breaks your heart the first few times you deliberately damage that finish though.) :smile:


#5

@brokendrum, @dwardio, @Jules
Thanks! Those are the answers I was expecting.

Dude. No kidding. I just spent an hour with a razor blade removing the dried foamed up parts from a project.


#6

I must have gotten lucky when I picked up the yellow stuff…sounds like the original foaming formula would have put me off Gorilla Glue forever. (And it would foam here.)

:sunglasses::+1:


#7

When building & repairing r/c aircraft, I wet each piece to be glued then apply the GG. Fills in gaps in foam and is pretty indestructible. Really useful in some cases.


#8

I think the idea of scoring is good. Think of tile bottoms, the channels give a place for the mastic to go, as well as increase the contact area.


#9

I use tightbond. I think it works better than Gorilla Glue and it dries clear. I just sand the edge. But, it is strong enough that you can brush it on super thin with a paint brush and then use a clamp and it will be good to go as long as both surfaces were clean.


#10

I’ve used Titebond I, II and III formulations, and to my knowledge, none of them dry clear. They are excellent glues though.

@Tom_A Did the surfaces have finish on them (polyurethane or something) or were they just raw plywood? If just raw plywood, scratching up the surfaces is not necessary. I would agree with others, I would not use original gorilla glue for this as it swells and will throw off the two pieces. I would actually use MORE glue than you think you need, spread it evenly (I use a $1 silicone spatula/spreader from the dollar store), and then clamp with even pressure as much as possible. (This could probably be accomplished by placing something heave on top, so long as it puts pressure on all of it. You will get some squeeze out…that means that you got it to contact everywhere…that’s what you want. I either just cut off that squeeze out after it has dried by using a table saw or other means, or just don’t worry about it, if you’re presumably lasering an object that might not go all of the way to the edges? Also, a damp paper towel works well to wipe up any glue squeeze out. Just wiping like this will not introduce enough moisture to the piece to matter. Be sure to either wipe it all off if you’re going to use that edge in the finished piece, or sand/scrape/cut it away because any glue left will resist staining or finish when you go to apply it.

I like Titebond II for the cost and product. It is kind of a yellowish color.


#11

I use I and II but as far as I can tell Tightbond I dries pretty clear. I do not go overboard with it and I’m sure it would be more opaque if I had a thicker coat of it.


#12

So, is the problem the squeezeout left over? When doing large glue-ups with finished edges I’ve used two things: tape (thicker pieces) or chapstick (or some other soft wax). I use these to mask the edges that are going to be affected by the squeezeout. Once the glue dries, wipe it away. I don’t typically wipe off squeezeout immediately after clamping if I’m worried about surface finish and have already masked the appropriate edges as it tends to smear it around more than anything. The wax/chapstick wipes off easy and shouldn’t affect the finished edges.


#13

This will seem really old school considering we are on a lser forum, but I think your best bet would be hot hide glue. It only takes about 30 minutes to cook up, needs no clamping (for flat, stiff material) and any squeeze out simply rubs off with your fingers once it has cooled down.This is a good place to start:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwizvcWk6JvXAhUjiFQKHUlyCzsQtwIIJjAA&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DstpmQfLrQPo&usg=AOvVaw3vlxtTaOn_L1Eu-Ue7R2dN

It involves a bit more work than just squeezing a tube, but the results are awesome.

If you want to just squeeze hide hot hide glue, another good starting point is:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=video&cd=1&cad=rja&uact=8&ved=0ahUKEwjksfW_6ZvXAhUBw4MKHVnTApUQtwIIJjAA&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DRQMV9jOsanQ&usg=AOvVaw2ze2fKInf5COBYCfBInaKi

Enjoy!


#14

Hot hide glue is used by all my luthier friends for stringed instrument construction and repair. Really important because you can steam apart hide glue but not regular wood glue. Instruments often need to be taken apart for repair.

But I have a question. I have a bottle of Titebond Genuine Hide Glue that I picked up last year. Haven’t had a chance to try it. Says it’s for furniture and instruments and is reversible. Directions show its use at room temperature, not heated. Wonder what the performance difference will be.


#15

Wow. So many interesting ideas! Who knew!

Thanks all!


#16

Titebond hide glue is genuine hide glue which has been modified with (from the label) cyanoguanidine and ammonium thiocyanate. These act as gel suppressants to lower the viscosity (thus liquid at room temperature).

A similar result can be achieved with traditional hot hide glue by adding urea, which will increase open time in hot glue, and if sufficient quantities are added, will result in a room temperature gel – Old Brown Glue.

Titebond performs as well as hot hide glue in bonding, but its reversability (the ability to take it apart) is not as good as Old Brown Glue or traditional hot hide glue.

Check your Titebond bottle, there is probably an expiration date on it.

Traditional hide glue can be poured out onto a non porous surface, and once dried hard, will keep practically forever. You just need to crush it up and re-hydrate.


#17

Chapstick = brilliant idea! Going to use it on a gluing project in a few minutes, thanks.


#18

If cost isn’t an option or the pieces are fairly small, a sheet of double sided tape will work well especially since you can cut it to shape. Depending on how thick the pieces are, and how vertical you need the kerf, you could glue first and cut second.

As you mention plywood is your material of gluing choice you probably want to keep the charred edges to hide the plys and therefore don’t want to sand away any char. But sanding will work for light smears. This weekend I removed a tiny bit of gorilla glue that seeped out of a joint with 400 grit sandpaper and a couple of light strokes.


#19

Great advice here. Yes, GG foams. I’d use CA because it hardens quickly; Titebond is great and will result in a stronger bond. I’ve only used hot hide glue once, but it’s old school cool… just note that it’s not vegan. :slight_smile: