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Thread: System 3 & West System Compatibility

  1. #1

    Default System 3 & West System Compatibility

    I have some System 3 penetrating epoxy that I want to use to coat the plywood skin on a storage box I am building. I want to attach stuff to the skin with West System epoxy. I am pretty sure the two epoxies will bond to each other if properly cured. But I'd rather check out my assumption here. Are the two brands compatible?

    Best,
    David

  2. #2
    Join Date
    Oct 2009
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    South Puget Sound/summer Eastern carib./winter
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    Default Re: System 3 & West System Compatibility

    No problem.
    The usual, be aware of blush.

    12 years...this is your first post!

  3. #3
    Join Date
    Oct 2017
    Location
    Middleton, Wisconsin
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    49

    Default Re: System 3 & West System Compatibility

    Why not test it to be sure?

  4. #4
    Join Date
    Feb 2006
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    Pennsylvania
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    Default Re: System 3 & West System Compatibility

    I've done this. No problem. It's not a bad idea to rough up the first coat with sandpaper if the first coat has surface buildup.
    -Dave

  5. #5
    Join Date
    Apr 2014
    Location
    Anchorage, Alaska
    Posts
    259

    Default Re: System 3 & West System Compatibility

    25 or so years ago I built the LadyC entirely with Sys3 poxy. The past year or so I have been refurbishing her using West System poxy. As expected, no issues.

  6. #6

    Default Re: System 3 & West System Compatibility

    Thank you all for your comments.

    And yes, 12 years. Time flies when you're having fun.

    With all good wishes,
    David

  7. #7
    Join Date
    Sep 2017
    Location
    Vilnius, Lithuania
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    31

    Default Re: System 3 & West System Compatibility

    Are there major differences between West System and System 3 epoxies: quality of bond, ease of use, price? Other?

    Best wishes,
    Jonas

  8. #8
    Join Date
    Oct 2009
    Location
    South Puget Sound/summer Eastern carib./winter
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    14,841

    Default Re: System 3 & West System Compatibility

    There are no major differences between the two.
    There ARE minor ones. Differences that one may not even recognise if you only use a little bit on occasion.
    They smell different, both wet and cured. (I can identify most epoxies years after they cure by the small of the sanding dust).
    Their hardeners have slightly different qualities . Mas "fast" , fer instance is F##KIN FAST!!! , while Sys 3 "fast".... not so fast.
    Different epoxies "blush" differently.
    And of course, we have different mixing ratios, but ratios change within a single brand!
    WEST is generally the most expensive, I recon between the advertising and their reputation as the gold standard "go to " , that explains that.
    The fellow who owns "Mas" has two smokin hot daughters who know how to "speak" epoxy...which makes them even hotter !

  9. #9
    Join Date
    Dec 2003
    Location
    CT
    Posts
    564

    Default Re: System 3 & West System Compatibility

    Hey, I just used one brand of resin with the hardener from another brand. Works great.

  10. #10
    Join Date
    Oct 2009
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    Default Re: System 3 & West System Compatibility

    That might be pushin yer luck.

  11. #11
    Join Date
    Oct 2010
    Location
    Central Vermont
    Posts
    280

    Default Re: System 3 & West System Compatibility

    Wizbang, I have been using MAS low viscosity for barrier coating for the first time recently, and you are exactly right that its Fast Hardener is Really Fast. Even when spread out in a roller pan, it goes off way faster than West Fast. I have been coating the side of my Lightning and finally learned that I just couldn't get up one side and down the other before that stuff got too sticky to use. I haven't timed it but I would worry if I couldn't complete the job in 10 minutes.

    And, not to digress, but the other really fast-setting product I have been using is 3M Marine Filler. It is really hard to use for filling the holes made by temporary deck clamping screws because you use so little of it at a time, and it feels like you only have about 5 minutes before it starts to set up. Of course, the good news is that, after 30 minutes in a warm garage, it is ready to sand, so you can move things along a heck of a lot faster than if you were waiting overnight for West Fillers to cure.

    I just got some Interlux Surfacing Putty because it doesn't have to be mixed but still sets up within a few hours. Much easier to use in small quantities than 3M. Haven't tried it yet but looking forward to it.

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