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Thread: Epoxy coating bulbs

  1. #1
    Join Date
    Aug 2003
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    Canada
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    Default Epoxy coating bulbs

    Can someone tell me how to coat a bulb and have it come out smooth? I tried pouring epoxy over the bulb and heating it with a hair drier but I get ridges and lumps(and it wastes a lot of epoxy). If I put it on with a brush I still get the ridges. When I try to sand the ridges I usually sand through the thin areas before it gets smooth. Does anyone have a slick method they are willing to share?
    Thanks
    Don
    Don Case
    Vancouver Island

  2. #2
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    Default Re: Epoxy coating bulbs

    Don - Thicken epoxy to mayonaise consistency - thick, but still a bit creamy/runny. Coat bulb and stretch a balloon over it. Will still have a few creases, but works (sort of) like the German Rubber method for latex on hulls. Work out excess via the opening in the balloon. From my experience, this is a 50% proposition - sometimes it works excellent - other times it looks like a dog-turd filled with kibble! Still haven't figured out what I do differently to have a good (or bad) finish. Still requires some sanding before painting.

  3. #3
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    Aarhus, Denmark
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    Default Re: Epoxy coating bulbs

    Hi Don

    If you have the ridges and lumps on the surface after the resin is cured, and wetsanding is the only way out, it often helps to apply a layer of tracer paint (Thin layer of spray paint). It makes it easier to spot when you have to stop sanding, but still it is allot of work.

    /Anders
    Don't count the hours... But make every hour count

  4. #4
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    Default Re: Epoxy coating bulbs

    Thanks guys
    Working off Dicks idea, I'm thinking I might try wrapping it with surveyers tape. It would flex enough to follow the shape and (hopefully) leave minimal sanding. I hate sanding. I'm just not sure how to hang on to the thing while I'm wrapping the tape. Five pounds of slippery lead with a pointy end, hmmmm. How did you deal with the fin slot Dick. I thought of filling it with wax but that would compromise the final glue joint. Maybe balsa.
    I've seen a bulb(Sails Etc, I think) that was covered in CF cloth. I'd like to know how the did that.
    Thanks
    Don
    Last edited by Don; 07-13-2011 at 02:02 PM.
    Don Case
    Vancouver Island

  5. #5
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    Jan 2006
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    Canada
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    439

    Default Re: Epoxy coating bulbs

    Hi Don.

    This how I did mine.

    After the lead was attached to the fin, I put the fin in a vice with the lead vertical. I thinned the epoxy and brushed it on with downward strokes. The epoxy flowed down the bulb and the excess dripped off. the last one (the Emo) came out well with practically no runs and needed very little sanding.

    John
    John Ball
    CRYA #895
    IOM CAN 307 V8

  6. #6
    Join Date
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    Default Re: Epoxy coating bulbs

    OK, the surveyers tape didn't work. It kept sliding down the bulb.
    John, I've tried that before but not with thinned resin.

    As I now have a bulb with a coat of thickened resin on it I will get a chance to try Anders sanding method. After it's sanded I'll try a coat or two of thinned resin. It is a few grams underweight anyway.
    Don
    Don Case
    Vancouver Island

  7. #7

    Default Re: Epoxy coating bulbs

    OK, something I used on a badly cast bulb (it just wasn't a good day for casting and i didn't feel like doing it over), was a product called "U-Pol Dolphin Glaze Finishing Putty"

    It is available as most automotive paint suppliers. A little bit goes a long way. It cures quickly (around 30 min) and it is SUPER EASY to sand and doesn't clog sand paper. It mixes up like 50:1 or 20:1 (can't remember and don't have the bag close by). It's also light weight, so if you're bulb is close to the desired weight it won't mess it up.

    I highly recommend it. Oh, it takes paint really well, also.

    But you do need to sand it to get a smooth finish. But like I said, it's really easy to sand, so it's worth it.

  8. #8

    Default Re: Epoxy coating bulbs

    Warm the bulb first,(until it's quite warm to the touch.. 50-60c) mount the bulb vertically, then lightly brush on the epoxy... You will end up with a nice thin even layer...

    Once cured, use scotch- brite to key up the surface prior to painting. That way you do not sand through.
    "Where ever you are going... Never take an Idiot with you, as you can always find one when you get there."

  9. #9
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    Default Re: Epoxy coating bulbs

    Don -

    my bulbs are usually already attached and faired to keel. Thus I have something to hold and hang fro

  10. #10

    Default Re: Epoxy coating bulbs

    If you think this is a challenge, try 19,600 kg!
    "Where ever you are going... Never take an Idiot with you, as you can always find one when you get there."

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