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Which epoxy?


jdb1930

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There is a comparison here but the 2006 prices are a little old. 

http://www.cozybuilders.org/ref_info/2006_06_Hunter_Resin_Price_Table.pdf

 

And a Gary Hunter presentation here.  Pay attention to what to use on fuel tanks and what he says about post cures.

http://www.cozybuilders.org/Oshkosh_Presentations/2006_EpoxyDoDonts.pdf

 

I have not bought epoxy in a few years and have lost track of hazardous material shipping costs but I suggest you start with a postal scale and a spreadsheet for mixing, then you can easily switch epoxies any time.  What I do is punch a hole in the cans, fill the cup with as much resin as I think I'll need and add hardener to bring the total up to the spreadsheet weight, then plug the can-holes with a machine screw when done and put them back in the hot-box.  It is not quite as fast as a dedicated epoxy pump but still pretty fast and accurate.  I don't trust the in-the-can-pumps.

 

I mostly used EZPoxy and 83 resin.  I liked MGS but it started to give me an itch.

 

Have you joined the Cozybuilder's list?  There is always some discussion of epoxies.  Search the archives. 

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-Kent
Cozy IV N13AM-750 hrs, Long-EZ-85 hrs and sold

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  • 2 months later...

I read :-   "  Rutan Aircraft Factory now recommends WEST SYSTEM epoxy for certain homebuilt aircraft applications, particularly where a moisture resistant epoxy is desired.... etc..

 

any comments on this appreciated. 

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I read :-   "  Rutan Aircraft Factory now recommends WEST SYSTEM epoxy for certain homebuilt aircraft applications, particularly where a moisture resistant epoxy is desired.... etc..

 

any comments on this appreciated. 

I will answer that with my best guess at the answer....

 

1.)  West System 105 Resin with 209 Hardener is an approved laminating system for the RAF Long-EZ / Cozy type builds.

2.)  105 Product Description - "105 Resin is a clear, low-viscosity liquid epoxy resin. Formulated for use with one of four WEST SYSTEM hardeners, it can be cured in a wide temperature range to form a high-strength solid with excellent moisture resistance"     209 Product Description - "209 Extra Slow Hardener is formulated for general coating and bonding applications in extremely warm and/or humid conditions or when extended working time is desired at room temperature. Provides approximately twice the working time of 206 Slow Hardener. 105/209 forms a high-strength, moisture-resistant solid with excellent bonding and barrier coating properties."

 

So, yeah, 105/209 is RAF approved, and according to the manufacturer it has excellent moisture resistance.

 

I don't have a clue what "moisture resistance" means, because all of our cured epoxies have excellent moisture resistance... and none of them have moisture resistance while being mixed / cured.

Interesting to me is that 209 is formulated for use in "warm and/or humid conditions"...  that may be a good reason to use the product.

 

Was that a good guess?

Edited by Andrew Anunson

Andrew Anunson

I work underground and I play in the sky... no problem

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Figure out a way to use approved epoxy. There is a Cozy for sale that nobody will buy because it was built with un-approved epoxy.

West is only approved with very slow (209) for layups. The faster hardeners can exotherm on some layups... so I suppose if an epoxy system can't be used for the entire build then it wasn't approved.

 

That being said, if you build with MGS and use all fast hardener you might get exotherm too.

Andrew Anunson

I work underground and I play in the sky... no problem

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Easy to say use an approved epoxy when you live in the same country as those approving epoxies.  :) 

Happily, I found local composites gurus who were able to advise on local options that are superior to West!

Aerocanard (modified) SN:ACPB-0226 (Chapter 8)

Canardspeed.com (my build log and more; usually lags behind actual progress)
Flight simulator (X-plane) flight model master: X-Aerodynamics

(GMT+12)

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Araldite K3600 (used to contruct Jabirus, apparently)

Adhesive Technologies ADR246 (used in at least 1 aircraft project and high-performance marine). This is what I am using.

Aerocanard (modified) SN:ACPB-0226 (Chapter 8)

Canardspeed.com (my build log and more; usually lags behind actual progress)
Flight simulator (X-plane) flight model master: X-Aerodynamics

(GMT+12)

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  • 4 years later...

I found this thread about what epoxy to use, but it is a little over 4 years old now.  I am trying to figure out what epoxy everyone recommends at this point?  I was considering the West System, but there isn't much talk about it.  Anyone have any opinions or personal experience with the West System Epoxy?

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West is popularly known mainly as a finishing epoxy, perhaps because West offers a variety of easily sandable fillers.

Gary Hunter has gone on record, along with Nat Puffer (I recall from a Cozy Newsletter), that West 105 with the 209 Extra Slow hardener is perfectly fine.

Looking at the properties, I am unclear as to why the 205 Fast hardener is excluded, but I tend to avoid fast hardeners anyway in favor of the longer working times of slow hardeners.

https://www.westsystem.com/products/compare-epoxy-physical-properties/

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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3 hours ago, Jon Matcho said:

West is popularly known mainly as a finishing epoxy, perhaps because West offers a variety of easily sandable fillers.

Gary Hunter has gone on record, along with Nat Puffer (I recall from a Cozy Newsletter), that West 105 with the 209 Extra Slow hardener is perfectly fine.

Looking at the properties, I am unclear as to why the 205 Fast hardener is excluded, but I tend to avoid fast hardeners anyway in favor of the longer working times of slow hardeners.

https://www.westsystem.com/products/compare-epoxy-physical-properties/

That makes sense.  I had seen a few articles where people were talking about Nat being good with the West 105 Resin I just couldn't find anything about what hardener was being recommended.  That helps!  Thank you!

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4 hours ago, Jon Matcho said:

Looking at the properties, I am unclear as to why the 205 Fast hardener is excluded, but I tend to avoid fast hardeners anyway in favor of the longer working times of slow hardeners.

Both West 205 and 206 hardeners are too fast and will exotherm on thicker layups, and also have pot lives that are way too short for large layups like spars and wing skins.

This has been explained and discussed infinitely many (slight hyperbole) times.

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1 minute ago, Marc Zeitlin said:

This has been explained and discussed infinitely many (slight hyperbole) times.

For those who have not memorized the Internet references are always appreciated.

For the life of me I was not able to find the source post or newsletter article from Nat declaring West 105/209 is OK, but found the slides from Gary Hunter's OSH presentations at www.cozybuilders.org showing 105/209 is "approved".

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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45 minutes ago, Marc Zeitlin said:

Both West 205 and 206 hardeners are too fast and will exotherm on thicker layups, and also have pot lives that are way too short for large layups like spars and wing skins.

Understood -- don't use fast hardeners for those sorts of layups. However, using that logic restrictions would be placed on other approved fast hardeners (Pro*Set and MGS for example). 

I definitely would NOT use the 207 Clear hardener, but based on the mechanicals for 205 Fast and 206 Slow hardeners I wouldn't throw parts away (assuming no exotherms). As I mentioned before, I prefer taking my time with slow (> 30 minute) hardeners, which is why I use only 209 Extra Slow (along with Pro*Set and MGS systems).

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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I used West a bit pre-airplane for small projects. It exotherms very easily. I have some small solid blocks of the stuff to prove it.

A study of the cured properties of various epoxies also shows that West has lower properties than other 'approved' products. Good enough, and it isn't like I have ever heard of a structural failure of one of these birds due to a low-quality epoxy. And makes it well-suited for filling, as it sands away easier. But given the ready availability of superior options, I went with a tougher resin for structure.

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Aerocanard (modified) SN:ACPB-0226 (Chapter 8)

Canardspeed.com (my build log and more; usually lags behind actual progress)
Flight simulator (X-plane) flight model master: X-Aerodynamics

(GMT+12)

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3 hours ago, Jon Matcho said:

Understood -- don't use fast hardeners for those sorts of layups. However, using that logic restrictions would be placed on other approved fast hardeners (Pro*Set and MGS for example).

"Fast" is a meaningless term - MGS "fast" is nowhere near as fast as either the West 205 or 206. Every epoxy combination is unique, so they have to be approved individually. Hence the approval of 209, but not 205/206, and yet the MGS and Pro-Set "fast"s are acceptable - they're still slow enough and not susceptible to exotherm unless it's very warm/hot.

I use 205/206 when I'm making thin, small parts and want fast cures, and when I'm NOT building weight critical parts or structural parts. Since they can kick fast, they can be difficult to squeegee well to reduce weight, particularly when it's warm.

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On 11/29/2022 at 4:16 PM, Marc Zeitlin said:

"Fast" is a meaningless term - MGS "fast" is nowhere near as fast as either the West 205 or 206. Every epoxy combination is unique, so they have to be approved individually. Hence the approval of 209, but not 205/206, and yet the MGS and Pro-Set "fast"s are acceptable - they're still slow enough and not susceptible to exotherm unless it's very warm/hot.

I use 205/206 when I'm making thin, small parts and want fast cures, and when I'm NOT building weight critical parts or structural parts. Since they can kick fast, they can be difficult to squeegee well to reduce weight, particularly when it's warm.

Well I will admit the reason for my post was due to the fact I couldn't find the page in my plans with the recommended epoxy options.  That page was stuck together on another page and I kept flipping over it and going all through the plans only to find RAF being referred to.  When I finally found out what happened I pulled the pages apart and discovered that it recommended the MGS 335 system as the better option out of all of them due to some of the properties.  Im all squared away.  Thank you!

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