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Thread: Polybrush question

  1. #1
    Bluebird19kf's Avatar
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    Default Polybrush question

    I’m covering a wing. I have just got done with the brush on coat of polybrush. I don’t know wether I did a good job or not. Is this a really sloppy job that will look bad later or is it normal? I’ve seen pictures where it looks like people don’t have it slopped out from under the tapes. Any advice is appreciated, Thanks
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  2. #2
    Senior Member
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    Default Re: Polybrush question

    Watch Project Kitfox on YouTube. Brian addresses this on his build.

  3. #3

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    Default Re: Polybrush question

    Looks like it's going on a bit thick, and developing runs. For the tapes, use a pencil to mark out the width of each tape, and stay within the lines when you apply the polybrush. It will make for a cleaner look.

    FYI, I'm no expert on this. I'm just repeating what I learned at the EAA workshop.
    Mike
    Building the JaMFox N677JM
    Kitfox 5 Vixen
    KRNM

  4. #4
    Bluebird19kf's Avatar
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    Default Re: Polybrush question

    So I decided to remove all my access polybrush. Problem now is that I have probably removed the polybrush that I brushed into the fabric weave. I’ve heard that if I proceeded with the spray coats I could get pinholes. So basically do you guys think I should brush another coat on?
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  5. #5

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    Default Re: Polybrush question

    I have seen videos of people spraying the poly brush to get an even no run coat.

  6. #6
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    Default Re: Polybrush question

    I have brushed a second coat on the poly brush. A while back, I bought an unfinished Kitfox 3 that was covered, and had the first coat of poly brush applied. It did look thin to me, so after washing the fabric with poly fiber's fabric cleaner (can't remember the name of it right now) I brushed on a second coat, making sure it was well pushed through the weave of the fabric. Sprayed the other coats, and it turned out fine. As far as spraying the first coat, the purpose of the first coat of poly brush is to encapsulate the fabric with the poly brush. The fabric is basicly plastic, and the coatings don't really want to stick to it. By pushing enough poly brush through the fabric so the poly brush sticks to it's self on the back side, the next coats stick to the first coat, and then each other as each coat is applied. That's why you should not spray the first coat. JImChuk

    PS pictures were in order when I uploaded them, middle pic is before I recoated with poly brush, third one is after second brushed on coat of poly brush, first pic is finished except for the red pin stripes to go on the yellow stripe.
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    Last edited by avidflyer; 01-08-2020 at 09:07 PM.

  7. #7
    Bluebird19kf's Avatar
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    Default Re: Polybrush question

    Thanks guys

  8. #8
    Senior Member ken nougaret's Avatar
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    Default Re: Polybrush question

    Like Jim said, the first coat needs to be brushed but not just brushed in a conventional way. By holding the brush vertically and stabbing/pushing into the weave, the fabric gets saturated.
    SS7 O-200 Whirlwind

  9. #9
    Senior Member Dave S's Avatar
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    Default Re: Polybrush question

    Bluebird,

    One point to remember is that if a person is brushing the polybrush into the weave properly, there will be a few runs that occur on the backside - that is not a bad thing - it indicates that enough PB has been applied to thoroughly saturate the weave - brushing it out keeps any runs off the outside - which would show through the final paint. Don't be concerned about runs on the backside.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  10. #10
    Senior Member 109JB's Avatar
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    Default Re: Polybrush question

    Right from the manufacturer's YouTube channel

    John Brannen
    Morris, IL
    Sonerai IIL (Single Seat)
    Kitfox 3/4 1050 - Rotax 582 (Back Flying and sold)
    Kitfox IV 1050 - Rotax 582 (sold)
    Kitfox IV 1200 Speedster - Rotax 912 UL (project)
    Piper Twin Comanche (Sold)
    Glasair 1 FT (Waiting to start)

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