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Epoxy not hardening

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olechap

Joined: 08 Jul 2007
Posts: 3
Location: Ellington, CT

Posted: Tue Oct 09, 2007 6:46 pm Post subject: Epoxy not hardening

Hey guys,



I'm having a problem with the epoxy (aeropoxy) I used for coating the cowl

surface.  I thinned with acetone per Van's directions, but after 4 days now

(or so) it's still tacky.  It feels smooth if you run your finger over it,

but if you just touch it - it's sticky.  



Batch was purchased 10 mo ago (no date on container)

Stored in 60F+ 

Parts are curing in a humidity controlled environment, 70-75F

Epoxy worked ok 3 months ago

Mixed by weight on postal scale 



That said, I think I figured it out... but check me.  A few of my colleagues

mentioned that my hardener might be the problem and that it needs stirring.

I opened the can and it had crystallized slightly.  I suppose if I read the

side of the can in CAPS where it says "MAY CRYSTALLIZE IN STORAGE" that I

would have checked earlier.  My questions are:



1.  Since I mixed a few batches without homogeneous hardener, would the

mixed remainder be of the wrong constituents and should I just throw it out?

I'm not planning on using this stuff for anything flight critical or

structural.  Perhaps I need to heat the hardener to re-mix it correctly?



2. How can I remove the sticky crap off the cowling so I can start over, or

is there something I can do to cure it?  Sanding just gums up the sandpaper

and acetone just made it stickier.  I tried a small corner of MEK, but

wonder if I'll hurt the prepreg substrate.  



Any suggestions?  All comments will be appreciated.



-Andy

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acepilot(at)bloomer.net
Guest

Posted: Tue Oct 09, 2007 7:22 pm Post subject: Epoxy not hardening

Order a new cowl?  DOH!  Just kidding.  What about that deadly stuff 

called MEK???



Scott

http://corbenflyer.tripod.com/

Gotta Fly or Gonna Die

Building RV-4 (Super Slow Build Version)



Andrew Olech wrote:



 	  Quote: 	
		  



 

Hey guys,



I'm having a problem with the epoxy (aeropoxy) I used for coating the cowl

surface.  I thinned with acetone per Van's directions, but after 4 days now

(or so) it's still tacky.  It feels smooth if you run your finger over it,

but if you just touch it - it's sticky.  



Batch was purchased 10 mo ago (no date on container)

Stored in 60F+ 

Parts are curing in a humidity controlled environment, 70-75F

Epoxy worked ok 3 months ago

Mixed by weight on postal scale 



That said, I think I figured it out... but check me.  A few of my colleagues

mentioned that my hardener might be the problem and that it needs stirring.

I opened the can and it had crystallized slightly.  I suppose if I read the

side of the can in CAPS where it says "MAY CRYSTALLIZE IN STORAGE" that I

would have checked earlier.  My questions are:



1.  Since I mixed a few batches without homogeneous hardener, would the

mixed remainder be of the wrong constituents and should I just throw it out?

I'm not planning on using this stuff for anything flight critical or

structural.  Perhaps I need to heat the hardener to re-mix it correctly?



2. How can I remove the sticky crap off the cowling so I can start over, or

is there something I can do to cure it?  Sanding just gums up the sandpaper

and acetone just made it stickier.  I tried a small corner of MEK, but

wonder if I'll hurt the prepreg substrate.  



Any suggestions?  All comments will be appreciated.



-Andy

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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rv8a2001(at)yahoo.com
Guest

Posted: Tue Oct 09, 2007 7:28 pm Post subject: Epoxy not hardening

When ever you have a problem like this I beleive you should always call the manufacturer, they know better than anybody as to what is going on. I had the same problem on the cowl and after calling the manufacturer they told me that it is normal to get a film on the surface of the epoxy......I dont remember the reasoning (its been 5 years) to get it off I just sanded, yes it plugged the sand paper but I had a bunch so......



 

Scott Bilinski

RV-8a



---

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mike109g6(at)insideconnec
Guest

Posted: Tue Oct 09, 2007 7:33 pm Post subject: Epoxy not hardening

Andy,

Try www.fibreglast.com for help.  They a resin company only and have a whole 

on-line help section.  I'm getting ready to do my epoxy work and have dealt 

with Fibreglast before when I was mold making.  Great source for products 

and advice.  Sounds like I should have posted it earlier.

Mike H 9A/8A

---

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Bruce(at)glasair.org
Guest

Posted: Tue Oct 09, 2007 7:43 pm Post subject: Epoxy not hardening

Set it out in the sun to warm up and cure.



Bruce

www.Glasair.org

 



--

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Larry Bowen

Joined: 09 Jan 2006
Posts: 802
Location: NC, USA

Posted: Wed Oct 10, 2007 3:20 am Post subject: Epoxy not hardening

It's called blush.  Easily removed with water and a scotchbrite pad.

-- 

Larry Bowen

Larry(at)BowenAero.com (Larry(at)BowenAero.com)

http://BowenAero.com  



On 10/9/07, scott bilinski <rv8a2001(at)yahoo.com (rv8a2001(at)yahoo.com)> wrote:[quote] --> RV-List message posted by: scott bilinski <rv8a2001(at)yahoo.com (rv8a2001(at)yahoo.com)>



When ever you have a problem like this I beleive you should always call the manufacturer, they know better than anybody as to what is going on. I had the same problem on the cowl and after calling the manufacturer they told me that it is normal to get a film on the surface of the epoxy......I dont remember the reasoning (its been 5 years) to get it off I just sanded, yes it plugged the sand paper but I had a bunch so...... 

Scott Bilinski

RV-8a



---

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_________________
Larry Bowen
RV-8 SOLD,
RV-7QB in progress...

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