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  1. #1
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    Prepping and repainting Marukin HC-300, any suggestions?

    I'm going to be refinishing a Marukin HC-300 (chromoly steel) I picked up. It has a good bit of surface rust, and shows tiny clusters of rust patches under the paint. This is my task list, but as a first timer I'm open to suggestions:

    1) Have frame sand/media blasted (should I insist on something other than sand?)
    2) Apply something like this: Corroseal Rust Converter Primer and sand.
    3) Apply coat of regular primer and sand
    4) apply coat of color and sand
    5) apply second coat of color
    6) decals
    7) clear coat

    Pictures here: Marukin HC-300

    Last edited by turbofeedus; 03-05-14 at 05:15 PM. Reason: added picture link

  2. #2
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    1st thing, if you are going to paint this with rattle can I would advice you dont do it and please use car paint polyurethane 1 stage and polyurethane clear coat. You need primer for polyurethane, no rattle can from home depot.

    All of that said...

    1 sand the frame down to the metal... done.

    2 use paper towels or something that doesnt have lint and clean the frame with rubbing alcohol just in case.

    3 prime the bicycle frame with good primer, maybe u-pol high built primer.

    4 - apply 3 coats of paint, 2 light coats and 1 heavy coat.

    5 apply decals

    6 apply clear coat... 2 or 3 coats, the 1st one has to be light, second one can be heavy.

    7 sand and polish if needed.

    8 done.

    If you use polyurethane car paint you can put the bike together maybe next day, with rattle can you wil need at least week or more and wait maybe a year for total curing of the paint, meanwhile sure that crap will start flaking. Use polyurethane.

    Good luck

    ps: did not add the sanding stages just because I'm assuming you did not have any troubles spraying the paint.

  3. #3
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    This is what I'm dealing with regarding the rust: http://imgur.com/23OnFWT

    I chose that primer because it's supposed to stop the rust process. Are you saying I don't have to specifically treat the frame with anything to stop the rusting?
    I was definitely going for the automotive paints, but yeah I'll make sure to get polyurethane. Thanks!

  4. #4
    Senior Member Kopsis's Avatar
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    Media blasting (if done properly) should strip the rust to the point where there's no oxide left to "convert". I've heard garnet recommended as a preferred media if you're looking for "show quality" results. Your first primer coat should be an "etching" primer. This will arrest the microscopic layer of rust that starts forming the instant bare steel comes in contact with air.

    After that, several coats of high-build primer, sand, prime, sand, prime, repeat until you get the desired surface quality. Avoid sanding through to the etching primer (using a different color sanding primer is very helpful here). You have some pretty significant pitting from rust, so you might want to use some spot putty (use a good two part putty) to build those areas. That will save you tons of time vs. trying to build back up with primer alone.

    After that, follow whatever process you desire for paint. Note that some decals are designed to be used under clear, and some over. Make sure you know what you are getting.

  5. #5
    coprolite fietsbob's Avatar
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    Or turn the job over to a powder coater and it will come back done ..

    the blasting to bare clean metal is part of the process ..

    just pick a powder color .

  6. #6
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    Quote Originally Posted by Kopsis View Post
    Media blasting (if done properly) should strip the rust to the point where there's no oxide left to "convert". I've heard garnet recommended as a preferred media if you're looking for "show quality" results. Your first primer coat should be an "etching" primer. This will arrest the microscopic layer of rust that starts forming the instant bare steel comes in contact with air.

    After that, several coats of high-build primer, sand, prime, sand, prime, repeat until you get the desired surface quality. Avoid sanding through to the etching primer (using a different color sanding primer is very helpful here). You have some pretty significant pitting from rust, so you might want to use some spot putty (use a good two part putty) to build those areas. That will save you tons of time vs. trying to build back up with primer alone.

    After that, follow whatever process you desire for paint. Note that some decals are designed to be used under clear, and some over. Make sure you know what you are getting.
    Show quality is definitely not a concern. If I thought I could get all that rust off the BB shell I would do it by hand. Is this a suitable etching primer?

    Quote Originally Posted by fietsbob View Post
    Or turn the job over to a powder coater and it will come back done ..

    the blasting to bare clean metal is part of the process ..

    just pick a powder color .
    I'm not trying to spend a ton on this project, maybe $100 tops. I doubt I could get the frame blasted and powdercoated for that much, but I haven't investigated either.

  7. #7
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    Use glass bead for blasting,not sand.You can use garnet but you have to turn the pressures WAY down.You could bore a hole through a bike frame with garnet if you wanted.

    In a perfect world you want what is called an anchor finish for painting or powdercoating.

    If you hunt around,you can get a frame and fork powdercoated for around $100 or so.

    I second using automotive paint,you'll be much happier with the results.Powdercoating will be cheaper than painting,short of using rattle cans.
    Last edited by Booger1; 03-06-14 at 03:26 PM.
    Everything should be as simple as possible...But not more so.---Albert Einstein

  8. #8
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    I've head good things about glass bead blasting and walnut blasting. Maybe I'll go with glass. I'll check out some powdercoating, but I'm already spending $50 for the blast.

  9. #9
    Senior Member Kopsis's Avatar
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    Quote Originally Posted by turbofeedus View Post
    Is this a suitable etching primer?
    I used it on an '87 Mongoose MTB that I re-built cheap (including rattle can paint job) as a commuter. Still too soon to really say how well it works, but after 18 months of daily commuting I have no signs of rust anywhere on the frame. However, I'm on the FL gulf coast, so rust is less of a problem than in northern climates.

  10. #10
    Home School Valedictorian 02Giant's Avatar
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    Spot putty is an old tech product, avoided by anyone who keeps current with automotive finishes. Etch primers can be quite finicky, epoxy primer is where it's at. Don't waste your money on the rattle can primer you linked, the finished product will not last.

    Talk to a powder coater before you do anything, usually stripping is included in their price, they have to stand behind their work.
    Last edited by 02Giant; 03-06-14 at 05:58 PM.

  11. #11
    Kittery Maine / NC
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    I just took my mtb to be blasted and powder coated. Cost $135. Came out WAYYYYYYYYY better than new. Freaking awesome job. Prolly would have cost me 50 bucks in paint and supplies, or more. And still would have a crappy paint job that chips if you look at it. Don't bother if you want a good job. Also, up here in Maine, I wouldn't be able to paint till July at this point, due to the fact that it is below zero, and just won't warm up.
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  12. #12
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    Ok after seeing the picture this is what you have to do...

    Find a place that can sandblast that frame, dont worry about the holes, is just metal pitting.

    The only difference with what you said and i said is that you need a really good primer, once that can built really good. If I was you and had the money I would go ahead and spray that with polyester/acrilic type of primer, that thing is thick and will built really nice covering all of that.

    Then sand it to get it really smooth and even, then you paint blah blah.

    The other option is sandblast, and then apply a polyester putty, not bondo, polyester ok? Bondo will start cracking, polyester will stick there and will move with the metal, it wont crack, just aplly that in there to cover the ugly area and then sand it untill you get it smooth, then primer then paint blah blah.

    3erd option. Just sandblast and then go with a dremel or any other power tool to smooth that area the best you can, then polyester primer or putty then primer, then paint blah blah.

    Hope this helps.

    ps: I would do a mix of #3 and then #1 .

  13. #13
    Senior Member Kopsis's Avatar
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    Quote Originally Posted by 02Giant View Post
    Spot putty is an old tech product, avoided by anyone who keeps current with automotive finishes. Etch primers can be quite finicky, epoxy primer is where it's at. Don't waste your money on the rattle can primer you linked, the finished product will not last.
    Chromoly bicycle frames are an old tech product OP is working on a $100 budget and that includes blasting. A single quart of 2 part epoxy primer will set him back $30 - $40 bucks (double that if he has to pay someone to spray it). Sometimes you just have to do the best you can with what you have to work with. In this case that either means a cheap powder coat or rattle-cans and spot putty.

  14. #14
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    Thanks guys, I'm going to see how much it will cost to have it powdercoated.

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