Author Topic: Aeropoxy Questions  (Read 4821 times)

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Offline propblade

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Aeropoxy Questions
« on: July 18, 2013, 05:48:47 PM »
I started using Aeropoxy for my project. I found that using the West System epoxy mini-pump and switching the pump bodies on the two hardener pumps (pulling the whole mechanism out of the cap, then switching caps and re-installing the pump body), then using the one with the larger cap results in a 3:1 ratio by volume. I did some practice layups with this setup, but noticed the cure time to be a lot longer than with, say, West system. Once cured, it still had a tacky feel to it and didn't feel as rigid as a similar layup with West. So, I tried another layup, this time mixing by weight (100:27), with the same results. I read on the company's website that this is likely carbamate, since my shop's RH is over 65%. Their recommendation is to peel-ply everything. I did a practice layup with peel ply and sure enough, it didn't have the tacky feeling. After about a week, all of my practice layups seem to have cured to a rigidity similar to West. Also, the description sheet says it should be a light amber, but when mixed it is as clear as West.

My questions, then, are, is this normal? (longer cure time, carbamating, coloration) Or might I be doing somethng wrong? What is the nominal cure time for Aeropoxy? My shop is at 78F and 60-70% RH.

All that being said, has anyone else run into this issue (carbamate, long cure times) with Aeropoxy? How does it compare to EZ-poxy? Would it be worth it to stick with Aeropoxy and peel-ply everything (other than the extra cost of the peel ply) or switch to another system?

(First 2 paragraphs cc'd to PTM-W) (Attempted to CC, but got an error from the submission form. Will try again later)
 

Offline BruceHughes

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Re: Aeropoxy Questions
« Reply #1 on: July 26, 2013, 10:12:27 AM »
First, Your posting is confusing.   Did you REALLY use West System pumps for Aeropoxy?   Your ratios would be wrong.
That is VERY dangerous.   You need to get some help AT YOUR SHOP, not on line.   Find someone who is an expert to
come over, share a beer, and SHOW YOU.

Second, try posting on canard-aviators@yahoogroups.com   I think there are MANY more people that use it.   Some are
expert.   I am NOT.

Third, anyone building or thinking of building should be in CSA.  See the home page of this website.  That is how to find people
to come to your shop and help.   It costs $30/year.    Iff that s too much, try building model airplanes.

Yes, I have had the amine blush as you described.

Bruce Hughes   :)


Offline propblade

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Re: Aeropoxy Questions
« Reply #2 on: August 09, 2013, 11:19:27 AM »
As I re-read, it did come off a bit confusing; the 300 series hardener pumps from West come in a 3:1 ratio and a 5:1 ratio. The cap on the 3:1 is too small for the Aeropoxy hardener, but the 5:1 cap is the right size. So, I removed the "guts" from them and swapped them, so the 3:1 pump now fits the Aeropoxy hardener can. I did several tests; volumetrically the pumps are accurate, as well as by weight. I manually weighed a batch as well, and had the same blushing results as I did using the pumps, and after the test layups cured, both appeared to have the same qualities. And that is all I've done so far, is test layups. I want to see what system will work best for my conditions. Aeropoxy was recommended to me by an instructor at EAA and on ACS' website. However in light of the issues I had during practice, I won't be using it. So, this is all academic as I opted to go with EZ Poxy.

That being said, what epoxy system has the deep brown color? The EZ Poxy (10A/83B) I have has a straw-yellow color when mixed. Is it the 84B hardener (slow cure) that is deep brown, a new formulation of the EZ Poxy, or a different system altogether?

Thanks for your insight and concern, Bruce, I truly appreciate it. I've been in CSA for three years; a deep well of information, for sure! I got a list from Beagle of local Canardians. Not a lot in MN, and only half-dozen close by (meaning within an two-hours drive), and of them, not sure how many still building. I'll review my CSA roster too. I think I posted this on C-A Yahoo, but I'll repost there too. Thanks again.

I started building model airplanes as a kid. I decided to switch to a real aiplane to save money!  ;D

Matt "Mars" Reed
« Last Edit: August 09, 2013, 12:09:20 PM by propblade »

Offline BruceHughes

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Re: Aeropoxy Questions
« Reply #3 on: August 09, 2013, 08:25:31 PM »
I still think you were using the wrong ratio of hardener/epoxy.   No wonder it did not work for you.

I never used those pumps; most of the structure was built when I bought the project so I weighed everything (in the CORRECT ratio).

Bruce Hughes   :)

Offline Bill James

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Re: Aeropoxy Questions
« Reply #4 on: August 10, 2013, 12:09:29 PM »
Matt-
Very interesting analysis.
     FWIW, many folks have picked an epoxy and stayed with it for simplicity and convenience, and to minimize the variables. I started with the predecessor of EZ Poxy and stayed with it. When I was building in the 90s, EZ Poxy had few issues and reportedly the best resistance to fuel which was encouraging. AC Spruce is the only source I have used, again the KISS principle.
     While I used it to build the plane, the cylinder plenums, an oil sump, and a myriad of other contraptions, there are in fact things I would not use it for.  That's a joke, kinda   :)   I am not suggesting that anything be assumed about the qualities or characteristics without one doing their own due diligence.
     Everyone has their preference. I have benefitted from using the standard EZ Poxy and know its curing characteristics. Still in the simple column, in cool wx I use a hair dryer (not a heat gun) for saturation during fabrication and overnight often have a drop light in proximity of the component. Obviously with any product it is prudent to be cautious of fumes and physical contact. Complete mastering of Rutans composite workbook is a given. Also, it is good to confirm that your heating system isn't creating an issue, space heaters in particular.
     
     An aside, early on when I was beating the bushes trying to get up to speed on things like epoxy and components and such, I got an interesting response from several folks about what particular type or brand they used. After talking about various qualities and capabilities of the particular item, when I got around to asking them which one they used and why, their response was, "Oh, it was given to me."
Back to square one.
Bill    :)
« Last Edit: August 10, 2013, 03:25:04 PM by Bill James »
Bill James, Fort Worth VariEze N95BJ
Downdraft Plenums, QuickCowls
There was supposed to be anhedral?
ATP, Society of Flight Test Engineers

Offline BruceHughes

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Re: Aeropoxy Questions
« Reply #5 on: August 11, 2013, 10:47:43 AM »
Matt:

When Bill James says "cool wx" he means below 100 degrees  <grin>.     Well, maybe Fort Worth, TX is not THAT hot but I
have seen some warm days in north TX.   Not like cool wx in Minnesota......   I have lived near the interstate both east and
west of him by 50-150 miles.

Bruce Hughes    :)