Epoxy taking long time to set

[Alan Lightstone]

I'm running into something odd. I have a batch of West System 105 Epoxy that I've been using a lot lately, that is taking a very long time to initially set (like when using the 205 fast hardener) it still hasn't set overnight.

It takes applying a heat gun to make it set.

Has the hardener gone bad, or the epoxy resin, or am I imagining things?

Temperature is around 72 in the shop, I even turned on the shop heater to heat ambient air temp up to 82, which didn't really help.

[Kevin Jenness]

It is possible you have a bad batch Have you talked to the manufacturer?

Have you had normal results with this batch of resin and hardener in the past and only recently are having problems? If so, I would suspect your mixing ratio (5/1) is off. If you are using pumps check what they are putting out with graduated cups. Make sure the proportions are correct, and that you are mixing the components completely.

I have used West System 105/205 for many years with predictable results, even with old resin that has crystallized and been rejuvenated and hardener that is dark red and smells like ammonia.

[Alan Lightstone]

Yes, the batch has been fine until recently. I am using the pumps. Is the 5:1 ratio by volume or by weight? Would adding additional hardener to see if it sets quicker prove anything?

[Alan Lightstone]

Actually, I just looked it up. It's 5:1 ratio by volume, or 5.19:1 by weight.

[Kevin Jenness]

Additional hardener will not help. You need the correct # of resin and hardener molecules to bind with each other. If the proportions are off spec the result will be also.

[mreza Salav]

You pump might be the problem (I once had this issue and realized it when I saw the amount of hardener/resin left was not proportional).
As far as I know they don't have a shelf life.

[Wade Lippman]

As far as I know they don't have a shelf life.

I have some that is about 15 years old. It is dark brown now, but still works fine.

[Chris Hachet]

Cold temps will affect epoxy also. I was doing some lamination work and my epoxy was setting slowly, moving the lamination work to the kitchen table helped my lamination work but not my marriage.

[Larry Edgerton]

Sometimes if the pump gets a little dirty the spring will not push it all the way to the top of the stroke. I check to see if I can pull it up further by hand. Have not had it happen on the resin pump.

[Chip Seltzer]

Is it possible that your mix has been contaminated by something? Just for example, a very small amount of white vinegar introduced to the mixture will prevent it from setting. Maybe something you are using to clean the joint prior to your set up? I would try one shot of resin and one shot of hardner in a clean cup, mix well and let it sit. It should "kick" within 15 minutes and should get very hot and set quickly thereafter. If it doesn't, I am guessing that either the resin or the hardner is contaminated. Obviously the next step is to replace one at a time until you find the culprit. One mistake can be applying the mix to the wood before the chemical reaction has had time to complete. That requires the mixture to be in "bulk" and not spread out thin. I keep a gallon of West 105 on tap at all times with a gallon in reserve. I keep a quart of fast and a quart of slow as well, pumps always in place. I have never had a properly mixed, clean batch fail to kick.

[Frederick Skelly]

I'd call the manufacturer tomorrow, Alan.

[Larry Edgerton]

Is it possible that your mix has been contaminated by something? Just for example, a very small amount of white vinegar introduced to the mixture will prevent it from setting. Maybe something you are using to clean the joint prior to your set up? I would try one shot of resin and one shot of hardner in a clean cup, mix well and let it sit. It should "kick" within 15 minutes and should get very hot and set quickly thereafter. If it doesn't, I am guessing that either the resin or the hardner is contaminated. Obviously the next step is to replace one at a time until you find the culprit. One mistake can be applying the mix to the wood before the chemical reaction has had time to complete. That requires the mixture to be in "bulk" and not spread out thin. I keep a gallon of West 105 on tap at all times with a gallon in reserve. I keep a quart of fast and a quart of slow as well, pumps always in place. I have never had a properly mixed, clean batch fail to kick.

That is simply not true. The exothermic reaction will complete as long as it is mixed well and your temps are within spec. Your supposition is a disaster waiting to happen on a complicated glueup. In Wests own manual it tells you to spread out on a sheet after mixing to increase the time you have to complete the glueup. They also advise packing the cup in ice if even more tine is needed.

You can speed the process by doing as you suggest, but it is not necessary and compromises the strength of the end product.

[Andrew J. Coholic]

Been using West systems since the late 80's. We use it regularly in the shop for several glue ups where regular woodworking glue doesnt work.

I have never, ever had a problem - and I doubt a bad batch would get through.

I have had the same issues at time with the pumps not wanting to return to the top of the stroke, and I always pull up on them to make sure the next pump gives a full metered amount.

Cold - well, I drop the temps in the winter in the shop to 58 F, and I use a lot more slow hardener than fast. Never had it not harden although the working time is definitely longer. Often I use fast and slow together as well, as long as the # of pumps is the same as the resin your good.

We generally go through the stuff faster than I wish we did (due to the cost) but I have been given some older resin that was discoloured and hardener that was very amber and stunk like ammonia. It still worked fine as the others have stated.

Im a firm believed that if the epoxy fails to cure, user error is probably the culprit... and what I'd investigate first. If you test the batch and it doesnt cure, I'd call them up and send back for testing.

[Alan Schwabacher]

I would suspect the pumps. If one partially clogs and makes the ratio wrong, that will prevent proper cure. For epoxy, as mentioned above, don't change the ratio. Think of the resin as having mortises and the hardener tenons: only the correct ratio will make the structure you want. If you change the ratio, you may make something, but it won't be the same structure.

Another possibility is crystallization. If you store the epoxy for a long time in cool temperatures, you might see solid on the bottom. This is crystallization of the epoxy. Mixing it with hardener will make it behave as if you had the wrong ratio because the solid part does not properly mix in.

You can bring crystallized epoxy back to proper behavior by warming and stirring until it dissolves. Then on mixing with hardener it will harden as usual.

[Chip Seltzer]

That is simply not true. The exothermic reaction will complete as long as it is mixed well and your temps are within spec. Your supposition is a disaster waiting to happen on a complicated glueup. In Wests own manual it tells you to spread out on a sheet after mixing to increase the time you have to complete the glueup. They also advise packing the cup in ice if even more tine is needed.

You can speed the process by doing as you suggest, but it is not necessary and compromises the strength of the end product.
My point is simply that spreading the mix before the reaction is underway can result in incomplete set. I have done a lot of this and have used ice to extend pot life on many occasions. In this case, the post is about a mixture that did not harden and that is a possible reason. My suggested "test" was to see if the problem exists in one of the cans (resin or hardner) or if it has something to do with his application.

[Alan Lightstone]

Been using West systems since the late 80's. We use it regularly in the shop for several glue ups where regular woodworking glue doesnt work.

I have never, ever had a problem - and I doubt a bad batch would get through.

I have had the same issues at time with the pumps not wanting to return to the top of the stroke, and I always pull up on them to make sure the next pump gives a full metered amount.

Cold - well, I drop the temps in the winter in the shop to 58 F, and I use a lot more slow hardener than fast. Never had it not harden although the working time is definitely longer. Often I use fast and slow together as well, as long as the # of pumps is the same as the resin your good.

We generally go through the stuff faster than I wish we did (due to the cost) but I have been given some older resin that was discoloured and hardener that was very amber and stunk like ammonia. It still worked fine as the others have stated.

Im a firm believed that if the epoxy fails to cure, user error is probably the culprit... and what I'd investigate first. If you test the batch and it doesnt cure, I'd call them up and send back for testing.

Good advice, Andrew. To clarify things, in a cup, the unused portion does cure. It just seems that thinner films to glue boards, etc... haven't been curing without heating. And with the addition of heat (often several hours later), the epoxy does eventually cure.

It has been a little cooler than normal here, lately, but as I mentioned in my initial post the shop temperature is invariably over 72 degrees. A few times to try to coax the epoxy into curing I put the shop heat on, and it reached 82 degrees. That ought to be more than sufficient, I would think. Certainly has been in the past, and according to the instructions.

How would you clean out the pumps? Acetone?

I'll probably run a test later where I'll use each pump and measure the weight of the dispensed resin and hardener, and see where it compares to West Systems required ratios.

[Chip Seltzer]

I tried to reply with quote but I guess I don't understand how to work the thread. In any event, I am aware of the methods for extending pot life and have used them all. In this case, the original post is about a batch (or batches) that are not properly setting and spreading the epoxy before it is thoroughly mixed can bring that result. My suggested test would determine if the problem was in one of he cans (resin or hardner, including the pumps) or in his application.

[Larry Edgerton]

My point is simply that spreading the mix before the reaction is underway can result in incomplete set. I have done a lot of this and have used ice to extend pot life on many occasions. In this case, the post is about a mixture that did not harden and that is a possible reason. My suggested "test" was to see if the problem exists in one of the cans (resin or hardner) or if it has something to do with his application.

And my point is that you are wrong.

[Chip Seltzer]

And my point is that you are wrong.
See West System User Manual page 36. Problem:Incomplete cure after cure time has passed. Cause number 3: Incomplete mix. That is what I was trying to communicate. I just didn't say it correctly. Sorry.

[Larry Edgerton]

[QUOTE=Chip Seltzer;2671469One mistake can be applying the mix to the wood before the chemical reaction has had time to complete. That requires the mixture to be in "bulk" and not spread out thin.[/QUOTE]

This is what you said. It is wrong.

[Andrew J. Coholic]

Good advice, Andrew. To clarify things, in a cup, the unused portion does cure. It just seems that thinner films to glue boards, etc... haven't been curing without heating. And with the addition of heat (often several hours later), the epoxy does eventually cure.

It has been a little cooler than normal here, lately, but as I mentioned in my initial post the shop temperature is invariably over 72 degrees. A few times to try to coax the epoxy into curing I put the shop heat on, and it reached 82 degrees. That ought to be more than sufficient, I would think. Certainly has been in the past, and according to the instructions.

How would you clean out the pumps? Acetone?

I'll probably run a test later where I'll use each pump and measure the weight of the dispensed resin and hardener, and see where it compares to West Systems required ratios.

To clarify, I drop the temp to 58 at night, and during the working day I bring it up to 64 or 65 F. None the less, cooler than your temps.

As for pumps I regularly get new ones. I feel every few containers of resin and hardener it isnt worth the few bucks to try and clean them or hope theyll continue to work perfectly long term. I usually buy the resin and hardener in a kit with new pumps, every so often (maybe once a year to a year and a half) and toss the old ones.

[Kevin Jenness]

"One mistake can be applying the mix to the wood before the chemical reaction has had time to complete. That requires the mixture to be in "bulk" and not spread out thin."

This is incorrect. It is important to mix the components thoroughly (the manufacturer recommends a full minute of stirring including scraping the sides and bottom of the mixing pot), but once the mixing is complete the reaction proceeds and spreading can begin. If you keep the mixed components in the pot it had better be a small batch and quickly spread or bad things happen. I have had to dump more than one batch that kicked off even in a roller pan and started smoking- sad!

To the OP: just measure out and mix a 5-1 batch by volume without the pumps, spread it out and see if it sets normally (resists fingernail denting in 4 hours @72*F). If so, your pumps need cleaning or replacement.

[Andrew J. Coholic]

Yes I make sure that (like anything you add hardener to) mix it thoroughly before adding any additives, and scrape the stir sticks and side of container you use to mix it in - and stir it up again.

[Chip Seltzer]

My reference to "in bulk" is misleading. I simply meant that I mix the resin thoroughly in the cup before I spread it. Incomplete mix can end up with incomplete set. I'm done with this for now. I apologize for the inaccuracy.

[William Fretwell]

When you have used up a fair bit in the tins and it's been standing a while you get an air bubble in the pump which can throw the ratio off.
Prime the pump and put that back in the tin. If your pipe at the base of the pump is loose or too short it can do the same.
I can think of no other reason.

[Warren Lake]

some chemicals have a certain life, auto finishes furniture finishes the catalyst can lose strength with time and how its stored. More likely to have issues with that than the resin, I dont have a ton of epoxy experience but have stuff that was recommended over the west stuff and have the west as well. Id be calling your supplier and asking about catalyst date and how old it is and if there is a decrease in its strength. The 15 minute thing not my experience, it was mix it well in a cup brush it on both surfaces minute later brush more on as it was end grain and some had soaked in and by the time I assembled stuff it was almost doing its thing. By the time my stuff was clamped the left over in the mixing container was hard. Temp will change that time. Mix it well and its ready to go, there were some epoxy primers I used in the past that had an induction time maybe an hour cant remember now. I also remember i had two or three catlyst speed choices in the brand I used.

[Malcolm Schweizer]

The fast hardener goes bad more rapidly than the others. Usually it turns purple or rust colored when it goes bad. The culprit is often humidity- not always, but that's a prime suspect. I do not buy fast hardener unless I really need it, and usually buy it in small batches. Note: West System's literature says the color does not affect cure time. They are wrong. Although the color itself literally does not affect hardening, I can tell you from a LOT of boatbuilding experience that if the hardener is turning dark, i.e. Reddish to purple hue, it's going to kick much slower and you need to use it up because it eventually will not kick at all.

As mentioned, test your pumps. It's easy to do. If it's a 5:1 mix then pump 5 hardener and it should equal 1 resin.

Freezing and thawing can cause epoxy to crystallize. Also taking it in and out of A/C to the warm outdoors can cause condensation. Moisture is not good for epoxy.

[Larry Edgerton]

Good advice, Andrew. To clarify things, in a cup, the unused portion does cure. It just seems that thinner films to glue boards, etc... haven't been curing without heating. And with the addition of heat (often several hours later), the epoxy does eventually cure.

It has been a little cooler than normal here, lately, but as I mentioned in my initial post the shop temperature is invariably over 72 degrees. A few times to try to coax the epoxy into curing I put the shop heat on, and it reached 82 degrees. That ought to be more than sufficient, I would think. Certainly has been in the past, and according to the instructions.

How would you clean out the pumps? Acetone?

I'll probably run a test later where I'll use each pump and measure the weight of the dispensed resin and hardener, and see where it compares to West Systems required ratios.

Ii just built a door with West. and it was slow curing for me as well, but in the morning it was hard. Humidity is very low right now here and that has an effect on epoxy as well.

I just clean the outside of the pumps, just where the shaft meets the seal. I use acetone or alcohol. Then I give the shaft a drop of light oil where it goes through the seal, has not been a problem.

By the way, if you buy sets and always have spare 207 pumps with the 1 gal extension around, they will screw on to a 1 gallon can of either acetone or alcohol. I keep one on a gallon of alcohol in my kit for cleanup. I find I am going through a lot less alcohol this way as well plus it is just handy.

[Mason Truelove]

I agree with you!
o advise packing the cup in ice if even more tine is needed.

You can speed the process by doing as you suggest, but it is not necessary and compromises the strength of the end product.[/QUOTE]

[Alan Lightstone]

So, some more info.

Finally got a chance to get back into the workshop, and I dispensed one pump each of resin and fast hardener and weighed them.

One pump of the resin delivered 20.7 g of epoxy resin
One pump of the hardener delivered 4.5 g of fast hardener.

This comes out to a ratio of 4.6:1 resin/hardener by weight.

According to the West Systems instructions, an acceptable ratio is 4.83:1 to 6.20:1 resin:hardener.

So, the pumps are no longer delivering an acceptable ratio. It's actually an excess of hardener in the ratio, not of resin. The question is, which pump (or both) aren't delivering the correct amount. Or has the hardener gone bad? Hard to imagine that a pump is delivering too much per stroke, so the I'm thinking the resin pump is delivering too little.

Still unclear as to whether I should replace the hardener and pumps, or will acetone clean them appropriately.

[Alan Lightstone]

Just cleaned the pumps with acetone. Ratio changed slightly. Now 4.77:1, so still less than West System's acceptable ratio, but closer. In theory, I could use one pump each, then a small pump of resin and likely be in the correct range. Or just replace the pumps.

The fast hardener is quite maroon colored at this point. They say that doesn't affect curing, but...