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MGS Epoxy 285 vs. 335


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I am about to place my first order from ACS and I am selecting the epoxy to use for the project. I am going to use MGS, but are there any opinions out there about System 285 vs. System 335? Is System 285 better in some way to justify the higher price?

Crazy Canuck

Toronto, Ontario, Canada

Cozy MKIV #MK1536

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The pros:

The 285 has higher Tg and strength properties. (Which are not significant in our application.)

It also wets out glass cloth a bit easier due to it's lower viscosity. (The 335 is still better than most of the other competitors.)


On the cons:

285 is MUCH more caustic to the skin and wallet. To me, the 335 is a more practical and possibly mildly safer product (health-wise), to use.

The increased cost, IMHO, is not justified by the advantages.

"I run with scissors."


Phase One Testing


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I have one other thing you might think about. When I started this project 3 years ago I was planning on using 335 resin I really thought it would be nice to use a resin that soaked in without a heat gun. Well it was not available for almost 3 months. I was anxious to start so I ordered eze poxy it was a bit cheaper. Now I am glad that I did It is much better stuff for building fuel tanks and I like brown airplanes. Just keep in mind some resins are made in this country are sometimes easier to get than resins made in other countries. my .02 Plus buying american stimulates our economy. STeve

Steve Harmon

Lovin Life in Idaho

Cozy IV Plans #1466 N232CZ


Working on Chapter 19,21

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What Jerry and STeve said.


One advantage to a higher Tg might be that you could paint your plane in something other than white?


Attached PDF, it's somewhat old, may be an interesting read.




Rick Hall; MK-IV plans #1477; cozy.zggtr.org

Build status: 1-7, bits of 8-9, 10, 14 done! Working on engine/prop/avionics.
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  • 1 month later...
  • 5 years later...

Here's a nice PDF of an Excel spreadsheet for those who want to use MGS 335 and a digital scale (I know..... BLASPHEMY!!).


I've had great success with a digital scale.  I prefer it in fact, and find it much more accurate and have never had to rebuild a pump. 


I now have a pump, but have not yet put it to any use... we'll see.

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

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