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Author Topic: epoxy...  (Read 1692 times)

Offline Bootlegger

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epoxy...
« on: May 24, 2018, 07:06:59 AM »

  Where can I get some one hour cure epoxy that will cure in one hour?  I got some and mixed a batch on Tuesday, here it is Thursday, and it's still not cured!!
  I am gonna contact the seller and complain..
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Gil Causey
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Offline James Holford

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Re: epoxy...
« Reply #1 on: May 24, 2018, 07:08:39 AM »
  Where can I get some one hour cure epoxy that will cure in one hour?  I got some and mixed a batch on Tuesday, here it is Thursday, and it's still not cured!!
  I am gonna contact the seller and complain..
Not enough hardener?


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Offline Steve Fitton

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Re: epoxy...
« Reply #2 on: May 24, 2018, 07:43:40 AM »
Look up the thread on EZ Lam that Brett Buck mentioned a while back.  Or, look at West Systems.

https://store.acpsales.com/products/2271/ez-lam-30-minute-epoxy-resin

Steve

Offline Brett Buck

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Re: epoxy...
« Reply #3 on: May 24, 2018, 09:02:38 AM »
Not enough hardener?

   Or too much. For most epoxies you are liable to run across in modeling, you get about the same result with either too much or too little of either component - it never cures completely.

    The reasons it fails to sure are pretty straightforward - it was mixed at the wrong ratio, it wasn't mixed thoroughly enough, it wasn't cured at the right temperature range (usually too low), it was contaminated with some third component, or it has expired. The first two are by far the most common.

      Brett

Offline Doug Moisuk

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Re: epoxy...
« Reply #4 on: May 24, 2018, 09:10:40 AM »
Try your heat gun or a hair blower. Warm it up. It will go off later.
Doug Moisuk
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Offline Brett Buck

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Re: epoxy...
« Reply #5 on: May 24, 2018, 09:19:42 AM »
Look up the thread on EZ Lam that Brett Buck mentioned a while back.  Or, look at West Systems.

https://store.acpsales.com/products/2271/ez-lam-30-minute-epoxy-resin

   Those are really good and very reliable (so far). EZ-lam is particularly good for, surprise, laminating (like sheeting foam wings) because it has a very long pot life and has nearly no tendency to self-heat. It cures pretty hard, hard enough to be able to sand with some effort. The variety of West Systems I have (from Uncle Jimby's *gallon* of the stuff) is extremely tough and doesn't get rock hard, so it holds tenaciously even when overloaded, and is very difficult to sand. Unfortunately I don't know what the actual type/part number it is.


     All of these epoxies are strongly reactive chemicals and definitely have a shelf life to them. As far as I can tell, most of the consumer epoxies last a pretty long time, even storing them in my un-airconditioned apartment (where it has been known to get to as high as 119 indoors on a few special occasions), on the order of decades. But they definitely go over the hill after a while. My buddies and I have had no end of problems with HobbyPoxy paint, for example, and it is my considered opinion that even sitting in unopened cans, it was probably over the hill. I would guess they made at most two production runs, one in the mid-60's and one in the '70s, and every can of it ever packaged was from the same factory batch. It's all over the hill and cures just like you mixed it wrong. I think Klass-Kote is probably very similar, if not the identical chemicals probably from the same plant. But it's fresh and works fine.

   The hardener of the most highly reactive types, like PIC Finishing Epoxy, tend to react their way through the container. Even the heavy polypropylene bottle it came it reacted strongly and made the entire bottle, on the outside, sticky. I had to pour it into a ZipLock disposable tub, and that turned glass-hard and brittle in about a week.

     Brett

Offline big ron

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Re: epoxy...
« Reply #6 on: May 24, 2018, 09:39:58 AM »
  (Those are really good and very reliable (so far). EZ-lam is particularly good for, surprise, laminating)

Would this Epoxy be suitable for laminating plywood fuselage doublers?
John Blanchard
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Offline Brett Buck

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Re: epoxy...
« Reply #7 on: May 24, 2018, 09:49:02 AM »
  (Those are really good and very reliable (so far). EZ-lam is particularly good for, surprise, laminating)

Would this Epoxy be suitable for laminating plywood fuselage doublers?

  Yes, probably ideal since it gives so much working time. It's very strong, too, but that is almost irrelevant for this application - huge sufrace area and very low local loads. Almost anything would work for this, as long as you got it applied and clamped before it started to set. 5-minute would be otherwise strong enough but you have maybe a minute or so total to assemble and clamp it. EZ-Lam 30-minute gives you easily 30 minutes even at elevated temperatures.

       Brett

Offline BYU

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Re: epoxy...
« Reply #8 on: May 24, 2018, 09:51:37 AM »
Unfortunately I don't know what the actual type/part number it is.
     Brett

West Systems Resin 105 plus either slow or fast hardener 206 or 205 respectively.
It sets up best overnight.

Add more hardener for faster setting.







« Last Edit: May 24, 2018, 01:38:13 PM by Bobs your Uncle »

Offline Perry Rose

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Re: epoxy...
« Reply #9 on: May 24, 2018, 01:33:56 PM »
Two hours ago wasn't Tuesday.
I may be wrong but I doubt it.
I wouldn't take her to a dog fight even if she had a chance to win.
The worst part of growing old is remembering when you were young.

Offline James Holford

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Re: epoxy...
« Reply #10 on: May 24, 2018, 01:52:21 PM »
Two hours ago wasn't Tuesday.
🤣🤣🤣🤣🤣🤣🤣

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Offline Randy Cuberly

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Re: epoxy...
« Reply #11 on: May 24, 2018, 02:00:09 PM »
West Systems Resin 105 plus either slow or fast hardener 206 or 205 respectively.
It sets up best overnight.

Add more hardener for faster setting.

I've found the West Systems 105 with the slow 206 hardener works very well here in Tucson even in the summer time when typical shop temps are about 85-90 even with my stinking air conditioner running full blast.  Nothing else I've tried will last more than about 8 minutes in the pot!

It also doesn't seem to be quite as critical on the mix as most other epoxies I've tried!

Good Stuff!

Randy Cuberly






























Randy Cuberly
Tucson, AZ

Offline Dave Hull

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Re: epoxy...
« Reply #12 on: May 24, 2018, 02:56:50 PM »
The EZ-Lam product is good stuff. I started using it instead of a prior product that required thinning to work well when using .58 oz/yd2 glass cloth. The thinning caused additional issues with curing--problems that you won't have with EZ-Lam right out of the bottles.

I have purchased at least three kits over the years. I keep it handy so when I am motivated to build, I don't have to wait. So far, it has been usable up to about 3 years. A batch last year didn't cure, so I ordered more. Problem solved. The latest kit came with stickers that gave the manufacturing date and expiration date. They are stating a one year shelf life, which is pretty good.

The part A may turn cloudy and thicken when the shelf life is up. You can warm the bottle in a pan of water and it then turns clear and looks normal, but you are at the end of life, and even if it cures, may not do so reliably. It also will not be as strong, but as Brett points out, for model building we hardly use the strength of the product. The part B hardener turns a bit darker--or else the bottle is getting stained. It does get sticky on the outside with age. Not from drips but from migrating thru the plastic.

If you have had epoxy applied for 48 hours and it has not fully cured, it probably never will. I have put items into the oven that were glassed using old epoxy and they did not fully cure. So removal/cleanup is the next step. If you are lucky it did not even begin to cure and you can scrape it off and solvent wipe. A bit of time to outgas and you are ready to start again. For a glass job, it is pointless to try sanding partially cured glass/epoxy. I found that I could peel up an edge and using a roller to wrap the fabric onto, continue to roll and peel. This was easy once I got it started. The parts were solid parts though. I would hate to try this over a planked foam wing! Maybe it would work in fairly narrow strips.

To make sure I get the proper mix, I use the small "K&B" cups and weigh both parts out on a scale. (Triple beam balance, actually.) I never mess with the ratio hoping to shorten or lengthen the pot life. Unless it is old--and I know it is old before I mix it--it has never failed to cure satisfactorily. I taper the tip of the popsicle stick so I can mix right into the corners of the cup.

Of the different epoxies that I have used, this one sands the best, isn't too brittle, and is thin enough for model work (laminating and glassing). I have also heard good things about West Systems. I believe its biggest claim to fame is that it will cure at fairly low temperatures. This is really important to boat builders working in unheated sheds, which I think was one of the original markets for the product. The homebuilt airplane guys use it a lot, too.

Dave




Offline Bootlegger

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Re: epoxy...
« Reply #13 on: May 24, 2018, 05:04:57 PM »

   I took it out of the fridge and let it set all day in my shop so it was at room temp, then I used a measuring spoon and mixed exact portions and it finally cured, apparentely I either didn't mix it correctly or didn't stir it enough, so I am going to use it again and be more careful.
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Gil Causey
AMA# 6964


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