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Thread: Help with primer

  1. #1

    Default Help with primer

    Applying Durabak to the inside of a truck bed. I have some bare metal that they say should be treated with a primer that is compatible with moisture-cured polyurethanes.

    Any suggestions ?

  2. #2
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    Quote Originally Posted by Tropicalcats View Post
    Applying Durabak to the inside of a truck bed. I have some bare metal that they say should be treated with a primer that is compatible with moisture-cured polyurethanes.

    Any suggestions ?
    any 2k urethane primer will do. an epoxy primer will also be ok. if you don't have a spray gun you can by it in a special aerosol can.
    b marler

  3. #3
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    What grit do you guys typically sand bare metal to before applying 2k epoxy?
    Similarly what grit would you sand filler areas to before epoxy?

    I want to be sure itís gonna stick but not have scratches telegraphing through.

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    Quote Originally Posted by SFLAutoSurf View Post
    What grit do you guys typically sand bare metal to before applying 2k epoxy?
    Similarly what grit would you sand filler areas to before epoxy?

    I want to be sure itís gonna stick but not have scratches telegraphing through.
    if you're doing bedliner like the op you could use just about any grit you want.
    if you're doing the exterior of the car, i usually do 180 for metal, 220 on filler. i don't worry about scratch marks coming through the epoxy. i shoot epoxy and immediately follow it with filler primer with the intent of blocking out whatever scratch marks remain.
    b marler

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    Quote Originally Posted by bmarler View Post
    if you're doing bedliner like the op you could use just about any grit you want.
    if you're doing the exterior of the car, i usually do 180 for metal, 220 on filler. i don't worry about scratch marks coming through the epoxy. i shoot epoxy and immediately follow it with filler primer with the intent of blocking out whatever scratch marks remain.
    No bedliner, just topcoat.. I just posted it here bc the title was primer help. I read somewhere to sand the metal waaaaay down to like 600 but that sounded crazy to me.

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    Quote Originally Posted by SFLAutoSurf View Post
    No bedliner, just topcoat.. I just posted it here bc the title was primer help. I read somewhere to sand the metal waaaaay down to like 600 but that sounded crazy to me.
    nobody takes metal to 600 for primer. you want some tooth to the surface for good mechanical bond.
    b marler

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    Thanks I knew that couldnít be right. I figured he mustíve misunderstood the question

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    Bare metal I take to 80 grit by hand before epoxy primer followed by 2-4 coats of primer filler. As bmarler stated you need good tooth.

  9. #9
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    Quote Originally Posted by Ronf View Post
    Bare metal I take to 80 grit by hand before epoxy primer followed by 2-4 coats of primer filler. As bmarler stated you need good tooth.
    i use 80 to strip the panel but i hit it with 180 to knock it down a bit. no problem filling the 80 grit scratch? (i know, that's what the filler primer is for.) i tend to let my stuff sit for a long time to tighten up so nothing shows up later. you work a little quicker than i do so if you aren't seeing anything pop up later maybe i'll stop the 180 grit. hard to break old habits though. choice of materials can have an impact too. the dp40lf you use is pretty bulletproof. the p sheet says 80 to 180 grit. i guess we're at the opposite ends of the range.
    b marler

  10. #10
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    Quote Originally Posted by bmarler View Post
    i use 80 to strip the panel but i hit it with 180 to knock it down a bit. no problem filling the 80 grit scratch? (i know, that's what the filler primer is for.) i tend to let my stuff sit for a long time to tighten up so nothing shows up later. you work a little quicker than i do so if you aren't seeing anything pop up later maybe i'll stop the 180 grit. hard to break old habits though. choice of materials can have an impact too. the dp40lf you use is pretty bulletproof. the p sheet says 80 to 180 grit. i guess we're at the opposite ends of the range.
    I should probably expand on this a bit. As I work on mostly 30's cars I seldom get an original panel without some kind of problem when taking the project down to bare metal. On these projects where I know extensive repairs will be required I really like the 80g for grip on the epoxy (2-3 coats). If the panel only has very minor imperfections and not going to be stored I will take it to 180g for epoxy and can immediately cover it with Evercoat Optex after flashing off (really like that product). When replacing a new aftermarket complete panel, like a fender on a 50's-60's classic, I hit the new metal with 80g followed by 180g followed by DPLF primer. I too have projects that are subject to sit for quite awhile (my 66 goat). In those cases I hit old panels with 80g followed by epoxy primer then into storage. You are absolutely correct, hard to break old habits. I'm with you in that 180g will work just fine. I actually think we are pretty much on the same page.

    Lol, why am I explaining this too you...geez you already know this. But it does make for good conversation
    Last edited by Ronf; 03-30-2021 at 05:56 PM.

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    Quote Originally Posted by Ronf View Post
    I should probably expand on this a bit. As I work on mostly 30's cars I seldom get an original panel without some kind of problem when taking the project down to bare metal. On these projects where I know extensive repairs will be required I really like the 80g for grip on the epoxy (2-3 coats). If the panel only has very minor imperfections and not going to be stored I will take it to 180g for epoxy and can immediately cover it with Evercoat Optex after flashing off (really like that product). When replacing a new aftermarket complete panel, like a fender on a 50's-60's classic, I hit the new metal with 80g followed by 180g followed by DPLF primer. I too have projects that are subject to sit for quite awhile (my 66 goat). In those cases I hit old panels with 80g followed by epoxy primer then into storage. You are absolutely correct, hard to break old habits. I'm with you in that 180g will work just fine. I actually think we are pretty much on the same page.
    Ron, How have you been leveling the Optex? I've found it difficult to level by wet sanding with 400 or 600 so I now level it with a pneumatic board covered with 220 then I apply my normal 2K filler primer and block it with 400 or 600.

  12. #12
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    Quote Originally Posted by Len View Post
    Ron, How have you been leveling the Optex? I've found it difficult to level by wet sanding with 400 or 600 so I now level it with a pneumatic board covered with 220 then I apply my normal 2K filler primer and block it with 400 or 600.
    I do a really quick surface skimming on a 6" DA and interface pad using 220. I really struggled with the Optex for quite awhile as it is like sanding concrete or clogging paper. Finally I found a solution with the DA, interface pad using 180 or 220 dry. You are not shaping at this point, just try and knock off the very top layer (literally takes just 20-30 minutes for an entire car) and go right back to your long board. It is a world of difference. On large projects after hitting with Optex I always wait 24 hours before the quick DA sanding and give a good wipe down with G&W remover prior, then do a quick DA skimming, you will be surprised at the difference. I have also used an inline air file as well, works okay but I really prefer the DA and interface pad. Just remember you are not shaping, you are only skimming and removing that top layer of paraffin AFTER a clean with G&W remover.

  13. #13
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    BTW, I can go straight to 400 wet hand block right after the DA and G&W remover for a perfect surface with little to no problem. I say little to no problem depending on the surface imperfections.

  14. #14
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    Quote Originally Posted by Ronf View Post
    I should probably expand on this a bit. As I work on mostly 30's cars I seldom get an original panel without some kind of problem when taking the project down to bare metal. On these projects where I know extensive repairs will be required I really like the 80g for grip on the epoxy (2-3 coats). If the panel only has very minor imperfections and not going to be stored I will take it to 180g for epoxy and can immediately cover it with Evercoat Optex after flashing off (really like that product). When replacing a new aftermarket complete panel, like a fender on a 50's-60's classic, I hit the new metal with 80g followed by 180g followed by DPLF primer. I too have projects that are subject to sit for quite awhile (my 66 goat). In those cases I hit old panels with 80g followed by epoxy primer then into storage. You are absolutely correct, hard to break old habits. I'm with you in that 180g will work just fine. I actually think we are pretty much on the same page.

    Lol, why am I explaining this too you...geez you already know this. But it does make for good conversation
    and good reference for future forum searchers.
    b marler

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