# 2-part epoxy vs. Gorilla glue?



## greenLED

Which one of the two would provide a stronger bond?

I'm making some G10 LED drop-ins for my brother, and I'd like to use some kind of adhesive to ensure a permanent bond between the plastic base and the metallic LED enclosure/heatsink. 

Both are joined by a couple of screws, but I don't trust the plastic material to hold long-term (?) and wanted to add a little extra something to hold everything together.

So, 2-part epoxy or Gorilla glue?

:thanks:


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## PCC

One thing you need to keep in mind when using Gorilla glue: it expands and bubbles as it sets up and cures. Try this experiment: put a drop of Gorilla glue onto a plastic bag then sprinkle some water onto it (per the instructions for using GG you are supposed to apply the glue to one surface and water to the other). That one drop of GG will expand about 2 or 3 times, bubbling as it goes, before it starts to set.

2-part epoxy does not tend to expand when applied and it does not tend to bubble so I would go with that instead.


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## mudman cj

I have used both many times, and in my opinion a good two part epoxy beats gorilla glue for strength. 

Gorilla glue is great when you need an expanding adhesive or when you don't want a two part adhesive.


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## olrac

mudman cj said:


> I have used both many times, and in my opinion a good two part epoxy beats gorilla glue for strength.
> 
> Gorilla glue is great when you need an expanding adhesive or when you don't want a two part adhesive.



+1

gorilla glue can be quite messy in a confined area due to expansion


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## sygyzy

What is situation you would want to use Gorilla Glue? When would you ever want your glue to expand?


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## greenLED

Thanks, guys. I'm aware of the expansion issues; they can be easily controlled, IMO.

I guess my primary concern is which one of the 2 would provide a more secure bond. Mudman's experience seems to point towards the 2-ton.

I've only ever used Gorilla glue in wood, leather, rubber.


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## Sgt. LED

2-ton
Gorilla eventually turns brown and powders. It's not pretty.


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## greenLED

Sgt. LED said:


> 2-ton
> Gorilla eventually turns brown and powders. It's not pretty.


2 votes does it for me. 
lovecpf


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## LuxLuthor

GG has too many downsides for me. I stopped using it a while ago.


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## adrianmariano

Fine Woodworking reviewed adhesives a couple years ago. Of course, their review was for gluing wood to wood, but they found gorilla glue to be the weakest of the glues tested. You can't necessarily generalize this to other materials, but it doesn't exactly inspire confidence. Epoxy was basically tied in first place with 2 other glues. 

There are lots of different types of epoxy. If you are trying to glue certain metals and you want a really strong bond, it may be worth checking its performance on the metals you are dealing with. For example, I needed a strong bond of brass to wood and I wrote to 3M tech support (which is very responsive) and they recommended a specific epoxy that can bond brass, which is apparently somewhat difficult to bond. (Note, however, that the 3M epoxies are somewhat more expensive than stuff at Home Depot. Home Depot is $5/25 ml. The 3M is more like $15/50 ml.)


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## Al Combs

I'm going to go the other way. I've never used gorilla glue. But I have used epoxy on plastic. I don't see it being an issue of strength as much as not flexible enough. Or perhaps it's the oily base of plastic that over time bleeds to the surface before it dries out. Something like Pliobond works fairly well in plastic/metal bonds. It's not as strong as epoxy, but it won't pop off either.


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## mudman cj

I used up the container of Gorilla Glue I bought and have not purchased another one since. I had it fail in a wood to wood bond after about a year that I later bonded more successfully using wood glue. Responding to the question from sygyzy, I really can't think of very many situations in which I would need an adhesive to expand. I guess that's why I haven't bought more of it. 

My favorite adhesives now are both two part epoxies that are useful for a wide variety of general purpose bonds. These are both industrial epoxies and are not inexpensive, but I can recommend them without reservation. The first is Tra-Bond 2116 which I have in the form of individual use packets and the second is 3M DP-460 or DP-460 NS in the form of a cartridge that fits into a dispensing gun. The NS version is non-sagging and has a higher viscosity to prevent it from running during the cure. 

I have also used common hardware store epoxies including 30 second, 2 minute, 5 minute, 6 minute, 15 minute and 1 hour epoxies, which is an indication of working time. To perhaps over generalize, it seems that longer working times tend to provide stronger bonds. I will no longer purchase a two part epoxy with a working time of under 5 minutes because I have not had good luck with them.


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## Al Combs

mudman cj said:


> To perhaps over generalize, it seems that longer working times tend to provide stronger bonds. I will no longer purchase a two part epoxy with a working time of under 5 minutes because I have not had good luck with them.


+1 on the only thing good about 5 minute epoxy is the time it takes. I have used a toaster oven on many occasions at 225-250°F to harden 24 hour epoxy in only 15 minutes. Funny thing is it's harder after cooling than it would be in a week of normal room temperature hardening. It's difficult to make a dent with a screwdriver after that kind of processing. Of course it's no good on some materials. Also the temperature changes the viscosity of the glue. That is it runs like super glue before hardening. Good if you need it to flow into cracks. Just don't go too hot as 300°F is what you use to destroy most epoxies.


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## fireboltr

there is only one gorilla glue adhesive I wouls seriously use over 2 part in you situation.... Its the rubber reiforced CA (super glue).....
its tough as heck doesn't expand and in some instances where a direct bond is available stronger....
I have gone to it for knife handles and such and find it to be easier and stronger....
of course you CAN NOT beat a reinforced epoxy for gap filling


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## LEDobsession

Cree states that Gorilla Glue is not safe for use on or around the XP-E (I know thats not what you're using but see page 6 of the PDF). I don't know if that would be recommended on other emitters as well, but I wouldn't even chance it. I like using 2 part epoxy for both bond and heat purposes as well. My two cents. :thumbsup:


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## adrianmariano

Al Combs said:


> I'm going to go the other way. I've never used gorilla glue. But I have used epoxy on plastic. I don't see it being an issue of strength as much as not flexible enough. Or perhaps it's the oily base of plastic that over time bleeds to the surface before it dries out. Something like Pliobond works fairly well in plastic/metal bonds. It's not as strong as epoxy, but it won't pop off either.



First of all, epoxy comes in a huge variety of formulations. If you go down the 3M catalog you'll see that they have one that is hard enough to sand and drill holes in and they have a "super flexible" one, and they have products in between. McMaster sells 15 different 3M epoxies (and 11 other two part adhesives that look like epoxy but are actually something else.) 

But that may not be the issue. Plastic is very tricky. Not all plastics are the same. If you want to bond a hard plastic, you may have good luck with a randomly chosen epoxy with good surface preparation (e.g. roughing up the surfaces). But if you want to bond a soft, slick plastic such as polyethylene then these epoxies won't work well. In fact, very few things will bond polyethylene well. For bonding acrylic, regular epoxy is also mediocre. 

For bonding general slick plastics ("low surface energy plastics") 3M makes DP-8005 and DP-8010 which work very well. They are kind of expensive and 3M does not recommend hand mixing, so you have to get the gun and use static mixing nozzles (10-1 mixing ratio). But they really work. I bonded zinc plated magnets to polyethylene with this stuff about 6 years ago and have been putting them through the dishwasher on a weekly basis without any failures. I use a sheet of teflon (PTFE) as a backer for epoxy work and regular epoxy pops right off. The 3M adhesive stuck to the teflon so well that I couldn't get it off. 

For bonding acrylic, you can use Weld-On #3 or #4 which basically dissolve the acrylic and melts the two surfaces together. (This is how you make an acquarium.) But the point is that if you want to bond plastic well you need to know what kind of plastic it is and seek an adhesive suitable for that particular plastic. 

If you're concerned about bond strength, then at least 3M (and I assume other manufacturers too) publish spec sheets with advertised bond strengths for different materials. As it happens, DP-460 was the product recommended to me to bond brass to wood. But I usually use epoxy for things that requires a fast set and I don't generally have any problems with bond strength. 

I have gotten the impression that in general, epoxies that bond more difficult materials or have other superior properties are slower curing, but I wouldn't try to generalize too far. I compared DP-100 Plus (4 minute open) to DP-460 (60 minute open). For DP-100 Plus the sheer strength in PSI for etched aluminum=3500, sanded aluminum=1800, ABS plastic=450, PVC plastic=250. For slower curing DP-640, etched aluminum=4500, sanded aluminum=3500, ABS=300, PVC=500. Note also that DP-460NS has sanded aluminum=2650. In fact, the non-sag version was significantly weaker on several materials. 

The observation is that if you're gluing aluminum, most likely the DP-100 Plus is adequate, but it is weaker. Note that for plastic, the DP-100 plus is actually stronger on ABS than the one with the longer open time. Surface preparation can make a significant difference. (Compare etched aluminum to sanded aluminum. You're better off etching your aluminum and using the fast product than sanding and using the slow product.) In the end, if you really care about bond strength, you should check the manufacturer specs for the material you want to glue rather than trying to infer it from working time. The DP-8005 that I used to glue to plastic has a 3 minute working time and bonds PVC with sheer strength of 2050 and ABS with 1575, much better than the DP-460.


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## ErickThakrar

DP-460 is an outstanding product that frankly has amazing strength when it comes to shear and peel. I've used it for a few years now and it's my go-to product for high-strength applications.


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