# Somebody educate me about epoxy



## skunked (Jan 4, 2007)

What are some good brands to attempt to glue glass to HA aluminium?


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## Anglepoise (Jan 4, 2007)

This is what I use. Its water clear and I use it on Tritium.
Sticks well to Ai.
LINK

I do not use this for Emitters to heat sinks.
Use Arctic Alumina from the shoppe for that.


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## Illum (Jan 4, 2007)

dont know much...but I can sum up what I know in seven words

sticks anything bonds forever and very flammable

EDIT: well, i tried a new batch....interesting, someone told me the Part A and part B before mix is very flammable...so I got some cotton swabs and went out to try it...nope...

sorry for the  , edited


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## FirstDsent (Jan 5, 2007)

I"ve never considered uncured epoxy flammable. It has no volitile component at all. Perhaps there is some formulation that is. Cured epoxy is difficult to burn. 

Epoxy is exothermic though. If you mix a large quantity of it, the curing reaction will overheat. The mixture will smoke (really nasty) and get very hot, however it will not produce open flame. It will not reach the ignition temperature of common materials. 

Bernie 

Bernie


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## 65535 (Jan 5, 2007)

Hmm remind me to get a lot of resin and hardener and give it to my friend..one time he pu tepoxy on himself iono why?


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## MoonRise (Jan 5, 2007)

Epoxy is a very broad term for a type of adhesive. Sort of like 'flashlight', which can range from a single 5mm LED to a 50+W HID to a 100+W paper-igniting incan.

Generally epoxies are composed of two parts, a resin and a hardener. When mixed, the components undergo a chemical reaction and start to cure via an oxygen 'rearrangement' reaction. Hence the "oxy" in epoxy. The reaction is exothermic (releases heat), and some epoxy formulations can have a pretty HOT curing reaction. I have melted a plastic stirring stick in a relatively small batch of curing consumer 5-minute epoxy, estimated temp around 250F.

Epoxies can be hard, or softer, when cured. Most epoxies can bond to dissimiliar materials, and most are water or moisture resistant when cured. UV will degrade most epoxies (and most anything else, except maybe metal).

Now, all that background out of the way, what and why are you trying to bond together? Glass to HA aluminum is pretty broad as a description goes. Something non-critical could be done with most any consumer-level epoxy mix, like from a hardware or automotive or big-box store. Do you need any special properties, like heat-resistant or clear or 'softer' bond? Just read the package and find what you want or need.


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## Thujone (Jan 5, 2007)

Anglepoise said:


> This is what I use. Its water clear and I use it on Tritium.
> Sticks well to Ai.
> LINK
> 
> ...



Looks nice but there minimum cc order of $25 means you would have to order 3 of their ~$11 12 packs to get any. I emailed them to see if there is a way around the minimum...


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## greenlight (Jan 5, 2007)

Anglepoise said:


> This is what I use. Its water clear and I use it on Tritium.
> Sticks well to Ai.
> LINK
> 
> ...




I like the product packaging on this one. I need to get a few packs.


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## abvidledUK (Jan 5, 2007)

Thujone said:


> 01001100011010010111011001100101001000000110100101 10111000100000011101000110100001100101001000000110 0100011000010111001001101011
> 00101100000011010000101001100001011011100110010000 10000001110100011010000110010100100000011101110110 1111011100100110110001100100
> 00100000011010010111001100100000011101000110100001 11001001100101011000010111010001100101011011100110 1001011011100110011100101110



http://www.adcott.net/binary/

Live in the dark,
and the world is threatening.

That's what it means.

I'm still none the wiser !!


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## Thujone (Jan 5, 2007)

abvidledUK said:


> http://www.adcott.net/binary/
> 
> Live in the dark,
> and the world is threatening.
> ...



You can interpret that many ways. I happen to believe it means that if you choose to go thru life in the dark (uneducated, unwilling to learn) then life is much more intimidating. However a more direct and more CPF centric interpretation might be, "Pick up a light! it is scary dark out there!"


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## Anglepoise (Jan 6, 2007)

Thujone said:


> Looks nice but there minimum cc order of $25 means you would have to order 3 of their ~$11 12 packs to get any. I emailed them to see if there is a way around the minimum...



They waive the min order if you use PayPal.
There shipping was a bit expensive but my order inc shipping and handling was 
$19.95.


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## mudman cj (Jan 6, 2007)

I recommend 3M two part epoxy DP-460. There is also a DP-460NS that has a higher viscosity and will not sag. This is an excellent epoxy for bonding glass or ceramic to metal. I have tried many epoxies in an effort to find a better one for bonding a ceramic to metal in a very high pressure application, and have not yet found a better one.


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## NewBie (Jan 6, 2007)

There is a very wide variety of epoxies on the market.

Epo-Tek, which is just one company offers over 50 different thermal epoxies, each one with different properties:
http://www.epotek.com/categories.asp?ID=2

Epo-Tek offers about 50 different optical epoxies:
http://www.epotek.com/categories.asp?ID=3

They offer about 50 different electrical epoxies:
http://www.epotek.com/categories.asp?ID=1

They offer about 30 general epoxies:
http://www.epotek.com/categories.asp?ID=4

If you register, there are over sixty technical papers to help folks address their specific needs, and to help them do a better job when using epoxy:
http://www.epotek.com/ssc-sign-in.asp

If you have a specific application, you can use their keyword search to help narrow down from the wide range of choices:
http://www.epotek.com/ssc-product-rec-key.asp


Unfortunately in rugged environments, long term, epoxies don't usually perform that well unless you know what you are doing, and then utilize it properly. Even then you can have issues. I've even seen lifelong epoxy scientists scratch their heads over field failure mechanisms. Thats why there is such a wide variety of epoxies on the professional market, some are made to bond certain similar metals, some dissimilar, or bonding metal to glass, where you have CTE mis-matches, or for things like rapid temperature changes.

Another specialty company, that is a bit more expensive, is Masterbond. They offer over a lot of different grades of epoxy:
http://www.masterbond.com/overview.html

They have 81 generic materials that are common use items, there are many more that are not listed in this quick selector guide for two component epoxies:
http://www.masterbond.com/sg/masterbond_2ptsg.pdf


Basic bonding and surface prep is covered here in this guide by Loctite, another epoxy manufacturer, that makes hundreds of epoxies:
http://www.loctite.com/int_henkel/loctite/binarydata/pdf/ACF205.pdf

A number of their epoxies can be found here:
http://www.loctite.com/int_henkel/loctite_us/index.cfm?verityspider=0&layout=4&productline=OEM6030&path=Assembly%20Products|Bonding|Epoxies

Some metal bonding information from loctite:
http://www.loctite.com/int_henkel/loctite_us/binarydata/pdf/lt3371a-v4_MetalBondingGuide.pdf

If you want to find one of Loctite's adhesives, call them, I once found rocket nose cone epoxy 1/4 mile away from me, at a pneumatic parts company, and as it turns out, they can nearly get any of Loctite's materials in 24 hours at no cost additional cost to me. What was nice about this material, was it's high temperature, it's high Tg point, and the fact that it could flex and take shock, while still having a high bond strength, and even hold up under both high humidity and high heat situations at the same time. Most epoxies don't have all those combinations.

A real datasheet will look something like the one in the link below, giving properites in a variety of situations, and the properties when two surfaces are bonded. Once, I saw this material here used, and lap sheer on abraded acid etched aluminum should have been 4,800 pounds per square inch. However, some assemblies were failing, and a simple tug would cause them to come apart. It turned out that folks who had cutting fluids, grease, skin oil, and WD-40 on their fingers were handling the surfaces to be bonded. The surfaces had isopropyl alcohol wipe right before bonding. Once proper handling was accomplished so the materials were not getting on the surfaces, and the person doing the cleaning learned how to properly wipe up invisible residue on the surface, instead of just smearing it around with an isopropyl alcohol saturated chemwipe, the parts had no problems meeting the specifications. Due to the environment where the parts were epoxied, a more agressive solvent was later used, to help assure the parts were clean before bonding.
http://tds.loctite.com/tds5/docs/HYSAE-120HP-EN.pdf


Loctite has a general catalog that has various materials available, suggestions, and applications charts. The epoxy materials can be found on page 20:
http://www.loctite.com/int_henkel/loctite_us/binarydata/pdf/LT3355v5_FullCatalog.pdf


As far as epoxies are concerned, there an inumberable number of formulations that are tailored to meet different engineering needs.


Even 3M offers a number of varieties of just the DP-460. Here is the datasheet for the low outgassing version:
http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs666yXcCOrrrrQ-

Of note, the cured Tg point (glass transistion temperature- where the adhesive becomes soft and rubbery), actually varies depending on the curing method and temperature. This is pretty much true for most epoxies. On page 2, you will note that the Tg point will move from 45C to 74C just from different curing temperatures. The Tg point is important, as it is at that point the epoxy will start expanding rapidly, which can lead to CTE mis-match failures between the epoxy and the substrate, which is also affected by bond line thickness and surface prep.

I have seen DP-460 fail routinely at my last company, in a certain rare earth motor assembly. Yet, they had been using it in many other areas without problem. Their process was fine, and the 3M folks even came in. The final fix for the failure was to utilize a primer on the surfaces before epoxy application, and to bake the assembly during cure, to raise the bond strength and the Tg point. We called 3M to let them know what the solution turned out to be. Often, the devil is in the details.

The 460NS epoxy datasheet is found here, at the bottom of page 3, note how they use a very agressive solvent MEK for surface prep, no pussyfooting around there...:
http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs666yvWCOrrrrQ-

A link to 3M's 20 epoxies:
http://products3.3m.com/catalog/ca/...uction_3_0/command_AbcPageHandler/output_html


IMHO, there is no automagical single epoxy. It is a complex goo that is affected by many different things.


.


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## I'M DK (Jan 6, 2007)

I'm not going to hit the "quote button" on Newbie's post.
I'll just say you asked for it.:wow:

DK


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## AdamW (Jan 6, 2007)

Wow.


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## HEY HEY ITS HENDO (Jan 6, 2007)

NewBie ....we`re not worthy! (“\(*-*)/”) (“\(*-*)/”) (“\(*-*)/”) you rock man !!


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## CM (Jan 6, 2007)

JB Weld it! :devil:


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## NewBie (Jan 7, 2007)

JB Weld works even better when you properly treat the surfaces, then it can be amazing at times.


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## CM (Jan 7, 2007)

NewBie said:


> JB Weld works even better when you properly treat the surfaces, then it can be amazing at times.



Surface prep is the key to a good bond. We always forget how important this is (probably just as important as the selection of the adhesive itself). Thanks for bringing that up.


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## NewBie (Jan 8, 2007)

No sweat, I've seen surface prep cause issues for many wonder adhesives in the past. Surface prep for RTV(silicone) is just as important, and especially so for any sort of oil, especially skin oils that are always on your fingers, even after washing.


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## NewBie (Jan 19, 2007)

I've even seen Arctic Alumina epoxied luxeons pop off their heatsinks when dropped.


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## skunked (Jan 19, 2007)

Okay, I think I can consider myself at least mildly educated. Thanks for all the help.


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## luigi (Jan 19, 2007)

For metal to glass
http://www.thistothat.com
recommends:
Loctite Impruv
http://www.thistothat.com/glue/loctite_impruv.shtml

Luigi


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