Last night I glued up a dovetailed frame using West Systems 105 Epoxy with 205 hardener and microfibre thickener.
I also glued and lightly clamped 2 scrap pieces.
After 8 hours the left over glue was still uncured and the scrap came apart when I unclamped it.
The temperature would have been about 27 deg C dropping to 24 over the “curing” period.
I propose to take the frame apart, clean up with acetone and reglue but would appreciate alternative suggestions and possible explanations of why this happened.
I bought and opened the resin in March.
Replies
From everything you listed, it sounds like it should have worked. I use 105 & 205 to do some veneer and bent lamination work ocassionally. My cans of the stuff are a few years old, and they still set up well, the ke being the proper ratio. I do not use the west system pumps, I just mix them up in a 5:1 ratio.
Your temps sound right for 205 as well. I've never used the microfiber, but assuming it's the 403, masde by west, I wouldn't anticipate any issues.
Without being there, the three things I need to question is how well did you mix the epoxy? Was it in the correct ratio, and was the mixing container contaminated? That's all I can really think of
Keep me posted
Gregory Paolini
http://www.GregoryPaolini.com
Custom Furniture, Cabinetry, and Woodworking Instruction
Thank you both for your inputs.I think that where I went wrong was in the measuring. I did not deliberately add less hardener but tended to a "slight" (I thought) excess of resin.The reason for this was not to get too rapid a cure. I have been caught out with fillers where, having mixed as per recipe (a golf ball of resin + a pea of hardener), the stuff hardened before I got it to the job.The good news is that it is curing slowly. It was "peanut butter" after 12 hours, "stiff dough" after 24 and "gum" after 36. I was in a position to dismantle the frame after 24 hours but decided to give it time and use the waiting time to fettle a plane and update my computer operating systems.Next time I'll make up the resin like a baby's formula.Again, thanks for your assistance.
>stuff hardened before I got it to the job.<One thing to realize is MUST be mixed as specified. Hardening rate is not determined by fudging ratio. To keep from hardening fast keep the mixed " puddle " spread out in a thin pool. If you stack it up in a cup it will get hot from the heat of the chemical reaction and that will accelerate the hardening rate and it will multiply. More heat even faster cure etc., etc., etc. If you need to take a break and stop for some reason put the puddle in the refrigerator. That will very much slow down the curing.Hope that helpsrocGive me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )
Haing learned my lesson, I hope to put all this into practice today.
I believe that while some epoxies have a non-critical mix, the West System ratio is critical. I could be wrong though.Chris @ http://www.flairwoodworks.com and http://www.flairwoodwork.spaces.live.com)
- Success is not the key to happiness. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
I think you're right. Proof of the pudding is, hopefully, later today when I attach the legs to the laundry trollet I am building.
All epoxies are a critical mix. The two components react together to form a new compound. Too little of the smaller volume B component results in under-reacted, therefor weak product. Too much results in the main A component being fully reacted, but with the excess B component unreacted and trapped in the finished product, thus compromising the strength of it.
BruceT
Bruce,Gee, I could swear that I read on one of my epoxy containers that it was a non-critical mix. I went down to the shop to check, but none made any such mention. I know I read it somewhere, but where?Chris @ http://www.flairwoodworks.com and http://www.flairwoodwork.spaces.live.com)
- Success is not the key to happiness. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
This is where I seem to have come undone. Some Epoxy **Paste** materials like Bondapaste and Chemical Metal state specifically that the ratio is non critical and actually suggest that you vary it to compensate for temperature.(Actually Bondapaste might be Polyester not epoxy, I forget).However in these cases it seems that the catalyst is just that. In Epoxies the hardener actually takes part in the reaction.
mix, mix, mix, mix and then press and spread, press and spread, press and spread stir,stir,stir,stir,stir, then mix some more really pressing it so there can be do lumps you are chasing around.
I have never used the fiber/filler but as I recall they have specific instructions for incorporating that into the mix.
West system wanted all sorts of sign up personal info and then wanted to snail mail their book. But System Three has this book
http://www.systemthree.com/members/literature/The_Epoxy_Book.pdf
you can get quick on line. Page down until you see contents page.
Here is and exerpt:
These fi llers , pigments and additives may be used with any of our
epoxy systems except for SilverTip Laminating Epoxy, which was
designed as a coating and fi berglassing resin only. Higher fi ller
loading levels are possible with Clear Coat epoxy because it is
much lower in viscosity than our other systems .
Fillers change the mechanical properties of the cured resin. For
all practical purposes the builder can ignore these changes.
Thixotropic agents have the least effect since they are used
in the smallest amounts to produce the desired result. Bulk-
ing agents reduce tensile strength in proportion to the amount
added. Some will initially increase compressive strength. With
increasing amounts of additives, though, compressive strengths
will decrease.
Many combinations of fi ller materials are possible and we have
not tested them all. If you have an idea that a certain combina-
tion might do something special for you then check it out. Little
pieces of scrap plywood are good for this. Think up some destruc-
tive tests that will simulate the stresses the material will see in
service. Check to see where the failure occurs. If the wood breaks
then your combination should work well with wood, at least.
The correct sequence for the addition of fi ller materials:
1. Correctly measure and mix resin/hardener.
2. Add fi ber fi llers
, if any, and mix well.
3. Add bulking agents , if any, and mix well.
4. Add thixotropic agent and mix well.
See also pages under SECTION IV - MEASURING AND MIXING
Exerpt: Customers
will call our Technical Support line suggesting that something is
wrong with the epoxy because it didn’t cure properly. We know of
no situation where properly-mixed resin/hardener has gone bad or
has been contaminated and wouldn’t cure. It always resolves that
the batch was either improperly measured or insuffi ciently mixed
in the user’s shop. Epoxy chemistry just will not allow it to work
any other way.
Measuring errors are insidious and can pop up when least expected. The reasons that errors occur are always because the technique changed, too little time was
taken, someone else mixed a batch, or just not enough care was
taken.
With the resin and hardener accurately measured, mix thoroughly.
For batches of a gallon or less, stir well, scraping the container
sides, and mix from the bottom to the top. Keep stirring until
that mixture is no longer hazy. Don’t worry about a few air
bubbles . That’s normal. Scrape the mixing stick several times on
the side of the container. Mixing takes anywhere from 15 seconds
to a minute depending on the size, shape of the container, and
temperature and viscosity of the mix. A sure-fi re way to make sure
that material is thoroughly mixed is to use the “two-container
method”. Mix in one container and then transfer the contents
into a second container scraping the fi rst into the second. Then
mix again. You will have an absolutely uniform batch if you do
this and avoid having partially
cured spots in your coating or
pour.
end of exerpt
The book is fun and has cool drawings.
mix, mix, mix, mix and then press and spread, press and spread, press and spread stir,stir,stir,stir,stir, then mix some more
roc
Give me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )
Edited 8/15/2009 1:25 am by roc
Edited 8/15/2009 1:26 am by roc
I had a similiar problem using Raka epoxy. The mix was probably a bit light on hardener. I thought the laminate was going to be scrap, I decided to leave it for another day. Next morning the epoxy was hard, just took longer to cure.
I always use measuring cups instead of relying on the pump dispensers.The one time I relied on the pump dispenser was this laminate chair rail.
mike
Hello again.I have used the same epoxy for another glue up and this time the results seem to be OK. The resin was almost fully cured (hard but a little tacky) after 50 minutes.It must have been the hardener. From measuring very carefully and thinking what I would have done while mixing the last batch I guess that I was at 1+6 instead of 1+5.Thanks for the advice and assistance.
If the resin to hardener ratio is off, it may eventually harden to a reasonable extent, but it will not get as strong as if the correct ratio were used. If flexibility is more important than strength to your application, a little off the proper ratio can get you there. But don't deviate too much.
Just for my own curiosity did you spend more time mixing and or use a different tool or way of mixing ? For example maybe before you used a screw driver in a cup but this time used a flat paddle shape and mixed on a pallet surface.By the way this is an excellent tool for mixing epoxy to spread the hardener throughout the resin :http://www.dickblick.com/products/blick-painting-knives/It is an artist's pallet knife designed to throughly mix thicker pasty stuff.Glad things are " coming together " for you: )rocGive me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )
Edited 8/16/2009 4:52 pm by roc
I am mixing 5 teaspoons of resin plus 1 of hardener, then adding 1 1/2 tsps of 403 fibre. I was more careful in measuring so that if I overflowed one spoon I underfilled the next.I did spend more time mixing but I doubt that that was the problem.
Coming late to this, but did you use the West system dispensers?
Unless you pre deliver and then fully charge them, they will give you a bad mix ratio and give you some of the problems you describe. With fully charged dispensers and the correct number of shots, I've never had a failure.
Boiler
I used teaspoons! Following my failure I have mixed 2 more batches which cured properly.Thanks for the input.
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