Super glue as wood hardener

ArcadeJason

ArcadeJason

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Working on a cabinet made of fiber board. Not a fan of wood hardener on fiberboard as it never seems to actually get hard and can react with paint if not fully dry. As an experiment i tried using super glue instead. I have to say I am very impressed!! The fiberboard sucks it up like a sponge and the glue instantly dries. I dare say it's even stronger than a new sheet of fiberboard. By far the strongest fiberboard repair I have ever seen. I am in no hurry but I will likely finish the body work in a day or 3. I will update if I run into any issues.
 
Fiberboard is super compressed so it doesn't breathe. But it also one of the best sponge materials on the planet. It's a slow sponge with a huge capacity. Those are 2 of its many (MANY) flaws.

It makes sense that standard wood hardener doesn't fully harden. It get sucked in and doesn't instantly harden. So it get pulled in deeper. And then it can't breathe. It needs oxygen to cure and the solvent needs to escape. But near the surface it hardens normally. And forms a really good seal that prevents the deeper stuff from curing. It will *eventually* cure fully but it takes a looong time. Whereas super glue cures "right now" so it doesn't have time to get pulled in as deeply.
 
I've always thought the Varathane wood hardener you can get at Home Depot was actually just a diluted form of super glue (cyanoacrylate).

I used two cans of it restoring my Avalanche cab, which is particleboard, and mine was falling apart from moisture damage. It worked well and fully hardened. But it behaved just like very liquidy CA glue, like it was diluted with acetone or something similar. Thin enough to soak into the wood before it hardens, instead of sitting on top of it.
 
andrewb said:
I've always thought the Varathane wood hardener you can get at Home Depot was actually just a diluted form of super glue (cyanoacrylate).

I used two cans of it restoring my Avalanche cab, which is particleboard, and mine was falling apart from moisture damage. It worked well and fully hardened. But it behaved just like very liquidy CA glue, like it was diluted with acetone or something similar. Thin enough to soak into the wood before it hardens, instead of sitting on top of it.
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looks like you may be right as super glue is an acrylic resin. i would bet wood hardener is using the oily cyanoacrylate though
 
In which case it made me wonder at the time if you could make your own.

Only because the Varathane is expensive (like ~$20 a bottle, IIRC. And one bottle doesn't cover much if you need to do many parts of a cab. I think I used three bottles total.)
 
Yeah, I used 3 bottles of Varathane on my Atari Basketball. It doesn't go very far. And after covid the price shot up. Just like everything else. :(
It's thinned with acetone. If the monomer is CA then that acetone must be ridiculously pure and dry. Any water at all will cause CA to polymerize. But then....acetone breaks down CA. Where is it end? Maybe it's ok in equilibrium? Is cured CA that is broken down by acetone able to re-polymerize after the acetone has evaporated? If so, will the newly cured CA be as strong as virgin CA?

I'm just pondering out loud. What do you guys think? My chemistry knowledge is old and faded.
 
greedycrisp said:
Formula Ive used for years: 72% acetone, 3% alcohol, 25% cheap acrylic resin. Soak the wood if possible, or make a dam around the area and keep pouring till no bubbles appear.
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Yup I have done something like this for years ^^
 
Interesting. I shored up the disintegrating base of my Eyes cab with a liberal application of Gorilla Glue, clamped down for 24 hrs afterwards a few years back.
 
cyanoacrylate had been used in wood working for years including repairing fine furniture. I've used it on a number of cabinets. It works particularly well to harden bloated and fuzzy MDF that's losing structural rigidity.

If you plan to use cyanoacrylate on a project it's best to either get the cheap no name brand thin CA from eBay or your local hobby store
 
DonPanetta said:
cyanoacrylate had been used in wood working for years including repairing fine furniture. I've used it on a number of cabinets. It works particularly well to harden bloated and fuzzy MDF that's losing structural rigidity.

If you plan to use cyanoacrylate on a project it's best to either get the cheap no name brand thin CA from eBay or your local hobby store
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^ This.

Remember, even Super Glue has a cure time - typically 72 hours for a "full bond" - read your instructions.

It will work fine, but with paint you'll want to wait until you stop smelling the VOCs (volatile organic compounds) coming from the repair BEFORE you apply paint.

Generally, double the full cure time will be sufficient.
 
ArcadeTechGW said:
^ This.

Remember, even Super Glue has a cure time - typically 72 hours for a "full bond" - read your instructions.

It will work fine, but with paint you'll want to wait until you stop smelling the VOCs (volatile organic compounds) coming from the repair BEFORE you apply paint.

Generally, double the full cure time will be sufficient.
Click to expand...

Agree with everything above. If i could give just one other tip it would be to use baking sheets for any areas you need to cover for clamping. Everything I've used either melt or clumps using CA and that includes baking paper but it's the easiest material i've found so far that will sand off. I would not use waxed paper, it will seep into the MDF.
 
cwilkson said:
Yeah, I used 3 bottles of Varathane on my Atari Basketball. It doesn't go very far. And after covid the price shot up. Just like everything else. :(
It's thinned with acetone. If the monomer is CA then that acetone must be ridiculously pure and dry. Any water at all will cause CA to polymerize. But then....acetone breaks down CA. Where is it end? Maybe it's ok in equilibrium? Is cured CA that is broken down by acetone able to re-polymerize after the acetone has evaporated? If so, will the newly cured CA be as strong as virgin CA?

I'm just pondering out loud. What do you guys think? My chemistry knowledge is old and faded.
Click to expand...


All very good points.

I was just going by how it smelled and acted. It made me want to try to mix the two, just to see what happened, but I didn't have enough CA on hand. But yeah, maybe the CA recombines once the acetone dries up? Dunno.

The fact that they don't seem to be very clear online (or anywhere else) on what exactly is in it (which I spent time trying to find) suggested to me that it's maybe not that complicated.
 
obitus1990 said:
Can you give more details on what cheap acrylic resin you use?
Thanks!
Click to expand...

I had a no-name bag of acrylic powder I got from a mold-making place. They used it to fill in casts to make models for trains & costumes, etc. But if you really dilute it with acetone it makes a thin gruel, not quite as clear as the store-bought wood hardener. Looking on Amazon it looks exactly like the stuff they're selling for acrylic nail salons but at inflated prices.

The last couple times I've diluted Minwax Polycrylic topcoat with acetone, works the same way, easier to mix.
 
I used a lot of what is called 'clear penetrating epoxy sealer' in boat building..
Smiths CPES was the brand I used. There are a number of others less expensive on the market now..
It is as thin as water.. seeps into the wood and the solvent evaporates leaving 2 part epoxy molecules behind to lock up the material (or in my case waterproofing wood).

I've used it a number of times repairing particle board cabinet bottoms .. it firms it all up nicely and lets you sand it all smooth. Then it can be filled with epoxy filler (which I prefer) or if it is just surface imperfections, Bondo..
 
I've never used this method on wood projects but for small holes in plastic resin (molded items, etc that will be painted), super glue and then sprinkle immediately with bicarb soda works a treat and sands out really nice. Works better than most bog filler products :)
 
Pinheadbloke said:
I've never used this method on wood projects but for small holes in plastic resin (molded items, etc that will be painted), super glue and then sprinkle immediately with bicarb soda works a treat and sands out really nice. Works better than most bog filler products :)
Click to expand...

The problem with this method on wood is that it would be harder to sand than the wood surrounding it and getting that to flatten out would be extremely difficult .

This also isn't the best solution for repairing plastic as it becomes more brittle over time. Plastic welding is really the best method for plastics.
 
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