Epoxy glue
- Thread starter Kittyhawk
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Kittyhawk...
I have the same problem..it now goes to a thick rubbery lump on the squeeze out....
I'm pretty sure it's not damp air in the tin as here the temp never gets much below 18º`c and averages out in summer to at least 25 ......
my tins are stored in a cool, dark UV proof cupboard.....
I dont use it a lot but so far it's just used for rubber bump stops etc.....as it's rubbery I might as well save a load of money and use a Polyurethene glue outta a caulking tube....which seems to work as well........
as tech shopping here has not really progressed since 1950, tube type epoxy is not generally available.....
although I managed to get the one last packet *2 tubes* from Lidil....
I have the same problem..it now goes to a thick rubbery lump on the squeeze out....
I'm pretty sure it's not damp air in the tin as here the temp never gets much below 18º`c and averages out in summer to at least 25 ......
my tins are stored in a cool, dark UV proof cupboard.....
I dont use it a lot but so far it's just used for rubber bump stops etc.....as it's rubbery I might as well save a load of money and use a Polyurethene glue outta a caulking tube....which seems to work as well........
as tech shopping here has not really progressed since 1950, tube type epoxy is not generally available.....
although I managed to get the one last packet *2 tubes* from Lidil....
Kittyhawk....
As you state that you only use a little at a time and the tins should last for months it indicates that the tin is opened frequently allowing fresh air in each time, apart from the fact that tins don't always seal adequately to prevent air ingress in storage. Epoxy components are reactive chemicals and will react with oxygen and water( moisture in the air ) as well as with each other. If you smell ammonia in the hardener then it is probably reacting with water. To try to prevent premature ageing try filling the tins with a blast of dry Nitrogen or other inert gas every time you close the lid. Cans of Argon are sold for preserving wine in opened bottles and would be good as Argon is very unreactive and is heavier than air so will sit as a blanket on the top of the resin.
Nigel
As you state that you only use a little at a time and the tins should last for months it indicates that the tin is opened frequently allowing fresh air in each time, apart from the fact that tins don't always seal adequately to prevent air ingress in storage. Epoxy components are reactive chemicals and will react with oxygen and water( moisture in the air ) as well as with each other. If you smell ammonia in the hardener then it is probably reacting with water. To try to prevent premature ageing try filling the tins with a blast of dry Nitrogen or other inert gas every time you close the lid. Cans of Argon are sold for preserving wine in opened bottles and would be good as Argon is very unreactive and is heavier than air so will sit as a blanket on the top of the resin.
Nigel
AES
Established Member
Kittyhawk
Established Member
Thanks for the replies.
Further to my post earlier in the thread that I was going to try something different, well I have.
Our ice cream comes in 2 litre square polypropylene tubs and when empty I cut them up into little squares to mix the epoxy on.
Last night I mixed up a small brew on a piece of 3mm MDF and it cured rock hard. I will repeat the experiment again today.
Perhaps some component in the epoxy is reacting with the polypropylene resulting in insufficient curing. Perhaps the reason why the non-curing symptom takes a couple of months to develop is that's how long it takes for the polypropylene surface to degrade sitting on a sunny shelf in my shop after being full of ice cream sitting in the fridge, thereby affecting the curing. This sort of knowledge is way above my pay scale. I would like to know, though.
I'm not convinced on age and air affecting epoxy. I have years old West System epoxy laminating resin in half full plastic jerrycans. The screw caps are a bit gummed up and don't seal so very well and the hardener has gone dark with a strong ammonia smell. West System's website says this is not detrimental and the resin still cures ok for me.
Further to my post earlier in the thread that I was going to try something different, well I have.
Our ice cream comes in 2 litre square polypropylene tubs and when empty I cut them up into little squares to mix the epoxy on.
Last night I mixed up a small brew on a piece of 3mm MDF and it cured rock hard. I will repeat the experiment again today.
Perhaps some component in the epoxy is reacting with the polypropylene resulting in insufficient curing. Perhaps the reason why the non-curing symptom takes a couple of months to develop is that's how long it takes for the polypropylene surface to degrade sitting on a sunny shelf in my shop after being full of ice cream sitting in the fridge, thereby affecting the curing. This sort of knowledge is way above my pay scale. I would like to know, though.
I'm not convinced on age and air affecting epoxy. I have years old West System epoxy laminating resin in half full plastic jerrycans. The screw caps are a bit gummed up and don't seal so very well and the hardener has gone dark with a strong ammonia smell. West System's website says this is not detrimental and the resin still cures ok for me.
English fellow I learned from here found the same thing with west. He had cans about 10 years old when I met him - one gallon per. metal, cans. I asked him why so much, and I can't remember anything but mumbling about it being "expensive". I also asked him about it going bad as a man who knows titebond can become iffy assumes the same for all glues and he said something about "never".
However, proof was never had as he punctured one of the two metal cans without knowing it and it ran out.
AES
Established Member
I am definitely NOT an epoxy (or any other chemicals) expert, but I believe that West Systems epoxy and Araldite are different beasts.
I have had experience of both, in the case of West Systems it was a "liquid" epoxy to be used for protecting motor/generator windings. Mine was acquired MANY yonks ago, and the hardener was a deep brown honey colour (and flowed like molasses!) plus stunk to high heaven of ammonia when I - finally - got around to using it. But it worked like a charm and cured "rock hard", even if browny coloured.
Whereas I have had Araldite (especially the 30 min stuff), 2 pack polyurethane (paint and clear varnish) and 2-part car body filler degenerate over - agreed an extensive - time period. And as others have said above, this is usually the hardener that goes first. And in my little "workshop fridge" this shelf life seems to be at least doubled or tripled, compared to storing it on an open shelf.
And the fridge trick definitely works well with all types of cyano acrylate (super glue) too.
You may well be right about a polythene container. If I ever acquire quantities of any such stuff "loose" I always make sure that it goes into a glass jar with a good lid. Apart from that, nearly all the stuff I've ever bought over the counter is in tubes, which as D-W said above, can be a nuisance because as the stuff ages it gets harder to get out of the tube without splitting the bottom of the tube.
The only stuff I've ever tried which comes on a "Siamese hypodermic" (V handy) is a 30 min epoxy called Devcon. Unlike the 30 min Araldite, which I find hardens off to a "slightly rubbery" state, Devcon does harden within the specific 30 mins. But the "Siamese hypodermics" are quite small and expensive for their size - more expensive than Araldite here anyway.
BTW, those "Siamese hypodermics" appear to be made of a pretty clear/almost transparent and reasonably flexible "plastic", but I wouldn't like to guess if that's PVC or something else. (Plastics is another subject that I don't know much about)
that's a bummer - the bottles are some kind of relatively flexible plastic that make squeezing really easy and they never seem to degrade into hard or brittle. I am no plastics expert, so I have no clue what they are. they don't suffer the death of a CA bottle, either (glue setting in the nozzle, degrading the plastic until the whole thing breaks), thankfully.
AES
Established Member
Kittyhawk
Established Member
The epoxy glue I'm currently using is Epiglue made by International Paints which is in turn an Anzio Nobel (spelling something like that ) company. It is regarded as the premium epoxy glue here in NZ and so it should be considering the eye-watering amounts of money they charge for the stuff.
The mix ratio us 2:1. Getting the proportions right in big batches is easy but not so easy on the tiny amounts I prepare. Whilst I'm reasonably confident with the mix ratio maybe a bit more attention to this is required.
The mix ratio us 2:1. Getting the proportions right in big batches is easy but not so easy on the tiny amounts I prepare. Whilst I'm reasonably confident with the mix ratio maybe a bit more attention to this is required.
Kittyhawk
Established Member
Same epoxy. Rubbery on polypropylene, rock hard on MDF.
AES
Established Member
OK Kittyhawk. Not heard of that one, though the Azko Nobel name is well known to me (their paints and primers, etc, are used a lot for painting full-size a/c).
As you say, mixing anything other than 1 to 1 in the small quantities you need must be quite difficult. But as you've "invested" in Epiglue, can I suggest either a piece of thin sheet metal (unpainted), glass, or glazed ceramic tile as the mixing "palate". Thoroughly cleaned off before first use of course (finished off with wipe with clean Acetone on a new tissue), and scraped off then Acetone again for subsequent uses.
But after that I'd suggest going back to standard (long cure) Araldite might be better for you - easier anyway, as you "just measure out" 2 little sausages of equal length on the piece of "plastic" sheet provided with the pack, using the "plastic" double-ended spatula-thingy also provided with the pack to mix the two sausages together.
I have no idea what that plastic is exactly, but as it's provided with the Araldite pack I'd say it's not likely to adversely affect either the mixing or the curing in any way. It's worth pointing out that after the epoxy has cured, any residue left on the mixing plastic, or on the spatula, all comes off quite easily - just flex the plastic a few times and the dead residue flakes off, ready for the next mix.
Pure guesswork on my part, but in the pic you showed of the Epiglue on MDF and on that piece of black plastic, somehow or other the mix on the black plastic is not curing fully due to some sort of interaction with that piece of plastic. But as said, pure guesswork here.
Does the Epiglue come with any "tools" to help you measure out and mix? It appears not (????)
As above, the Araldite does come with the "tools" included (well it does here anyway!) and I've always found that measuring out is not too critical anyway - "roughly equal length sausages" works fine. I've found what IS critical is cleanliness - both the mixing palate, the mixing tool, and both parts of the joint MUST be clean and grease and dust-free. I always finish off my clean up, (before mixing and applying the mix to the job) with a drop of clean Acetone on a clean tissue.
HTH
There is a very big difference between an Epoxy and Polyester glue in the polymer chain, the Epoxy chain stays in line and is critical to its mixing ratio as the binder does not move on to cure any resin that has not been mixed in the correct proportions, in a Polyester the catalyst moves on down the polymer chain and attracts the chains to each other, hence polyester resin will shrink when curing, but Epoxy does not, polyester is not usually affected by moisture as its a thermic reaction, Epoxy is affected by moisture and at times will not go off or just reaches a rubbery state.
AES
Established Member
I won't pretend to fully understand the chemical process/es and reactions involved Mike, and I certainly could not argue with you. But all I know from practical usage experience is that:
A) Within reason, Araldite does not seem to care all that much in it's cure provided that i) the "sausages" are of ROUGHLY equal length - by eye; and ii) whatever is squeezed out of the tubes is thoroughly mixed up;
and
B) All this "fancy" chemical stuff (various 2 part paints and varnishes, various fillers, and lots of 2 part glues, plus cyano) all seem to at least double their stated shelf life if kept in the fridge and only brought out shortly before use/put back again right after use.
Works for me
Kittyhawk
Established Member
I think my epoxy curing problem is resolved.
Firstly I like to pass on what somebody told me years ago. As we know the correct ratio of glue to hardener is important, and the smaller the mix the harder it is to get it right. The Epiglue I am using is a 2:1 mix and the way to mix it is to divide the components into three equal amounts - two equal amounts of glue and one equal amount if hardener. This is much easier to eyeball than trying to visualize whether that single dollop of glue is twice the size compared to that dollop of hardener.
Using little squares of polypropylene as mixing palettes was I think the cause of my glue not curing but not from being contaminated in some way. Epiglue is self supporting on vertical surface when mixed but the glue component is a lot more runny than the hardener. The polypropylene squares are very smooth, have a waxy feel and are reflective. I had been placing two equal amounts of glue on the palette, closing the glue tin, opening the hardener tin and scooping out the required amount. In the interim the two dollops of glue had been slowly oozing outwards in a thin almost invisible film thereby reducing the sizes of the glue mounds that I was using as a reference for the hardener amount. Result - incorrect mix ratio.
As to why the mix was OK for a few months and then started going bad, I had the same problem at this time last year. Its early summer. Temperatures over the last week have gone from 18° to 24° lowering the viscosity of the glue component... and the reason why it cures when mixed on MDF is that it has a grippy textured surface, the glue doesn't spread out over it so the mix ratios are much more likely to be correct.
I'm sorry for this long winded explanation but hopefully you can derive some benefits from my ****-ups.
Firstly I like to pass on what somebody told me years ago. As we know the correct ratio of glue to hardener is important, and the smaller the mix the harder it is to get it right. The Epiglue I am using is a 2:1 mix and the way to mix it is to divide the components into three equal amounts - two equal amounts of glue and one equal amount if hardener. This is much easier to eyeball than trying to visualize whether that single dollop of glue is twice the size compared to that dollop of hardener.
Using little squares of polypropylene as mixing palettes was I think the cause of my glue not curing but not from being contaminated in some way. Epiglue is self supporting on vertical surface when mixed but the glue component is a lot more runny than the hardener. The polypropylene squares are very smooth, have a waxy feel and are reflective. I had been placing two equal amounts of glue on the palette, closing the glue tin, opening the hardener tin and scooping out the required amount. In the interim the two dollops of glue had been slowly oozing outwards in a thin almost invisible film thereby reducing the sizes of the glue mounds that I was using as a reference for the hardener amount. Result - incorrect mix ratio.
As to why the mix was OK for a few months and then started going bad, I had the same problem at this time last year. Its early summer. Temperatures over the last week have gone from 18° to 24° lowering the viscosity of the glue component... and the reason why it cures when mixed on MDF is that it has a grippy textured surface, the glue doesn't spread out over it so the mix ratios are much more likely to be correct.
I'm sorry for this long winded explanation but hopefully you can derive some benefits from my ****-ups.
AlanWS
New member
I've used System Three epoxy after at least a decade, and it's worked well. The hardener can yellow but that only affects appearance.
One thing that can happen is that if it's stored cool you can crystallize out part of the resin. You will see a solid at the bottom of the liquid, and if you mix up a batch that crystallized part won't enter into the reaction so it will behave as if you had mixed the wrong ratios: it will cure only to a rubbery state.
The fix is easy: just warm and mix the resin (not mixed with hardener!) until the solid dissolves, and then the epoxy will mix and cure fine. That might fix your problem.
One thing that can happen is that if it's stored cool you can crystallize out part of the resin. You will see a solid at the bottom of the liquid, and if you mix up a batch that crystallized part won't enter into the reaction so it will behave as if you had mixed the wrong ratios: it will cure only to a rubbery state.
The fix is easy: just warm and mix the resin (not mixed with hardener!) until the solid dissolves, and then the epoxy will mix and cure fine. That might fix your problem.
Jameshow
Established Member
Slightly off topic but in a way related....
Many years ago as a kid I built my first control line model aeroplane. It was a kit solid balsa affair paw 1.5 engine etc.
I built it carefully with my dad painted it, and came to the fuel proofing which was two pack. I'd never heard of it before and my dad must have been working, I put one jar on without any knowledge of the hardener!
Many years ago as a kid I built my first control line model aeroplane. It was a kit solid balsa affair paw 1.5 engine etc.
I built it carefully with my dad painted it, and came to the fuel proofing which was two pack. I'd never heard of it before and my dad must have been working, I put one jar on without any knowledge of the hardener!
Interesting. I'm somewhat late in life to start woodworking, at least relative to people who did it all along (started around 28 or 29), but built airplanes in my youth. Everything was CA glue and anything else was task named, like you say "fuel proofing". I don't remember much about anyone using the word "epoxy" too often but to say that you could use it to reinforce inevitably broken fancy planes and get them flying again until they became so heavy that the wing loading got too high to fly easily (can always make them go faster, but rough on landing with places that have landing lights and posts sometimes!)
Also remember as a kid being sparing with the CA accelerant and never wanting to use much, but rather pin things and wait because every penny counted as a kid - or at least I felt that it did, even when it didn't.
I have some nostaglia for that era, too - yesterday I replaced the epoxy I was using because the hardener stinks and the mrs is apoplectic about it. If I take a PTO day and do it at 9 in the morning and she works (infrequently, so I take the opportunity) and I glue a couple of knife handles *outside* and then put them in a bucket and bring them in to cure with a lid on the bucket, she can still tell.
Bob Smith Industries was a big supplier to the hobby industry back then, along with Zap-a-Gap stuff. The companies hadn't been bought and sold or wiped out other than for brand, and maybe that's still true of BSI, but they didn't come up with obscure names or hidden ownership. What should the company be called? Just put "industries" after the founder's name and make the customer service phone connection competent and important not by just automatically allowing returns for cheap imported goods, but by having the same person answer the phone every time and provide assistance and answers in a minute or two. We paid a little extra for it, I guess. After the amazon and VC funded brand purchasing and stripping to get market share has seemingly gone full circle (squeeze the old timers on price, then get their market, then raise price back up and replace quality with continuous marketing).
My era (1990s) was the R/C era, but pre-turbine, and the hobby was lively. Membership in a club and insurance was cheap and at least half a dozen people were at the field any given time. When I drive by it now, there's rarely anyone there and the gate is usually locked. I guess people are at home on their devices.
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