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  1. #1

    Default primer before bondo?

    Im halfway through stripping my car back to metal. When im done im sure ill need to use abit of bondo. So do i go bondo straight on the metal or should i spray a coat of primer first? Thanks in advance mateys!



  2. #2
    Join Date
    Sep 2008
    Location
    Hollister
    Posts
    50

    Default to prime or not to prime

    After striping you need to hit the car with metal prep, then give it a coat of epoxy primer if you don't want any rust to develop.Then you do your body work. Work one panel at a time so that as a beginner you don't get overwhelmed. For large areas you need to use bondo, and you need to apply it to ruffed up bare metal. After applying the bondo use a cheese grater to remove the glaze coat and ruff out to shape then use 36 or 40 grit sand paper and sand to shape leaving the bondo high the depth of your sand scratches then move to 80 grit and knock out your 36/40 grit scratches then prime with a primer filler, when it drys mist it with black spray can primer, this is called a guide coat, then block that with 180, the guide coat will stay in your low spots and sand scratches, when the black is gone the scratches are gone. Any small stuff can be fixed with a polyester putty, It can be applied over primer ruffed up with 80 grit sand paper,then use 80 grit to block out the putty, then prime with a primer filler, block with 180 and prime again. Lacquer primer filler will not hold moisture out. so if its going to be more that a week before it gets paint, block it with 220 and hit it with epoxy primer. Good luck Craftyken

  3. #3

    Default

    good info there..wish I would have read this before I started on my '30 coupe, my buddy works at a body shop and what we did was lay marglass down first to the bare metal and then bondo over that..was that a dumb idea? I trusted him since he's a body man so figured he knew what the hell he was doing but maybe not haha
    Arrowood Rod & Kustom
    www.arrowoodrodkustom.com

  4. #4

    Default

    CRAFTYKEN, ill give you a plane ticket to come and do all that to my 51...aha :P
    exellent advice though...

  5. #5

    Default

    it really depends on who you talk to about body work. everyone does it thier own way. what i would have done is prep the bare steel with 80 grit. then get an epoxy made to go to bare steel or an acid self etching primmer to lay down first. then as said before use body filler (not bondo brand filler) on the large noticeable spots. depending on how big they are you may need to use a cheese grater, or usualy i use a hard pad D.A. sander with 80 grit on it to knock down the high spots and feather the edges. then i go at it with a sanding block with 80 grit to get it straight. the i glaze the repair again either with reduced filler or an icing to fill pin holes, sanding scratches or minor low spots. then i block that with 180 grit to get it where it needs to be. come back with a soft pad D.A. with 320 on it and sand the area around the filler and over the filler to reduce the 180 scratches a bit, then prime it with a medium to high build polyester primmer ( not slick sand). apply 3 good coats and then dust some black guide coat on. once you do this to all the spot on one pannel to reblock everything with 180 grit and prime annd guide coat the whole pannel. block and prime whole pannel as needed to make it flaw less. if you are worrieed about waves on your pannels you can take some prep all on a rag a wet down the whole pannel and look down the side to see how it will look with shine on it.

    i have found if you use a cheese grater or 36 grit sand paper and do not apply another layer of filler, whether it is straight filler or icing the scrathes tend to be visable later on down the road in the paint at the right anlges. same with priming over 80 grit scrathes. most primers if you reat the tds sheets it says to use 180 -320 grit sand paper. the scarthes can come back to haunt you in the end.

    this is how i and all the people at the the body shops i have worked at in the past have done it and everything turns out great

  6. #6

    Default acid etch primers

    etch primers, in the midwest anyway, wont have the ingredient "chrome" in itvery much longer. a law just passed saying that chrome cant be used anymore. this is what gives the primer its bite. there are etch primers out there already that dont have chrome in them, i was highly advised not to use these primers. they will not last

    the correct way to do it is epoxy primer without baking it, it takes a long time to dry but thats what makes epoxy so durable and long lasting. this is THE way to do it if u wanna make it last

    my 2 cents

  7. #7
    Join Date
    Feb 2008
    Location
    at the house
    Posts
    303

    Default

    good info so far...

    this last build im doing is staright to metal and all epoxy first then over some putty filler to build up ****s alot of work to block straight the lower quarters of a 61

  8. #8

    Default

    as far as my shop goes we use Speiz Hecker paint sysyem.

    filler is only recommended over their catylized 2k primer. putting any type of solvent based primer or laquer primer on your car is a horrible idea. (except a weld thru primer when you're chopping things up) laquer primer will make your paint explode when you start spraying the paint on.

    --

    If I'm not mistaken you don't want to use filler over an etch primer because the acid will react with the peroxide in the filler over time. then you get yellowing of the paint and other failing of product.

    ---

    the filler itself is made to only be used over bare metal substrates (or fiberglass). the only filler that is specifically listed as OK over anything but bare metal is a skim coat product, or "pooky" it basically really thin bondo made for final finesse work.

    as long as you're working in a dry shop you can leave a car in bare metal infinately.

    if you wipe the bare metal off with solvent when you're done working it and getting fingerprints on it, it will be fine.. any little surface rust prints can be easily sanded off before primer.

    -


    if you're worried about rust just strip it, sand it with 180 and prime it with a 2k primer surfacer.. then move on to bodywork.. either sand and do your filler on top of the primer, or sand it off and do your filler on the bare metal.. unless you're doing a gloss black beauty queen this method should do you fine
    Last edited by biGshiz79; 05-26-2009 at 04:39 PM.
    Bodyman, painter, frame guy.. basically I hit sh*t with hammers..

  9. #9
    Join Date
    Sep 2008
    Location
    Hollister
    Posts
    50

    Default Guess I ruffeled a few fethers

    Let me address a few of the things.
    My post was diy post, someone doing a RAT Rod in their garage taking six months to a year or more to paint their car, and on a budget.

    cornfield customs: started his post by saying:everyone does it thier own way. what i would have done is prep the bare steel with 80 grit.

    craftyken:I started my post as the car already being striped = Bare steel.
    It doesn't matter how you get their!

    cornfield customson: the large noticeable spots. depending on how big they are you may need to use a cheese grater, or usualy i use a hard pad D.A. sander with 80 grit on it to knock down the high spots and feather the edges.

    craftyken:I owend a body shop for 12 years, I payed for all the sand paper. body filler has a glaze coat and the cheapest way to get rid of it is with a cheese grater not a new 80 grit.

    cornfield customson: i have found if you use a cheese grater or 36 grit sand paper and do not apply another layer of filler, whether it is straight filler or icing the scrathes tend to be visable later on down the road in the paint at the right anlges. same with priming over 80 grit scrathes. most primers if you reat the tds sheets it says to use 180 -320 grit sand paper. the scarthes can come back to haunt you in the end.
    this is how i and all the people at the the body shops i have worked at in the past have done it and everything turns out great.

    craftyken: In my shop I would turn out compleat paint jobs in three days, panel repairs delivered in one to two days. In these cases I would not prime 80 grit. because primers continue to shrink even catalyzed.depending on the product for weeks. This is why paint manufactures make grit recommendations. And in a body shop your doing base coat clear coat, not rat rod satin. In theory with a long enough cure time you could prime 36 grit.

    cornfield customson:then i go at it with a sanding block with 80 grit to get it straight.

    craftyken: Getting it straight, I always say you cant fix any thing, with anything less than 80 grit. And for an area six to eight inches across 80 grit is a good grit to start with, but any thing larger, 36 or 40 they make it for a reason. And for a beginner it will help you learn how to make thing straight because you can see whats happening better. And your paper cost in the long run will be cheaper. If cornfield customs is buying you sand paper burn up all the 80 grit all you want.

    biGshizzle79: as far as my shop goes we use Speiz Hecker paint sysyem.
    filler is only recommended over their catylized 2k primer.

    craftyken: These are not the most budget friendly products, I think Speiz Hecker is owned by DuPont. I'm sure that they are good products, Maybe one of the best.
    but their are plenty of good budget friendly products out their that are great for a beginner working on their rat rod. DuPont has a line called Omni that is way cheaper than their normal line. I did a singel stage 10 years ago, that people think is a two stage base clear that still looks good. Evercoat has good products that are priced very well for their quality. Just go talk to your local auto body supply.

    biGshizzle79: as long as you're working in a dry shop you can leave a car in bare metal infinately.

    craftyken: I used to live in Utah. I when I 17 I in rolled in trade school for auto body and paint. As part of My tuition I received a proto pick hammer and a universal Dollie, that thing was nice and shine, it stayed that way for 16 years, then I moved to California. With in a week that Dollie along with the other half dozen Dollies I have, developed a coat of rust. and they were in a dry tool box. The sooner you prime bare metal the better.

    Cornfield customson and biGshizzle79 along with others have some good professional points and I totally understand were their coming from.
    But the best way to learn is with baby steps.
    That's what I'm putting out their, baby steps for the DIY Rat Rod'er on a budget.

    craftyken....................................
    Last edited by craftyken; 05-28-2009 at 03:45 AM.

  10. #10

    Default

    you really didnt ruffle my feathers, i was just giving the way id things in my shop. not saying mine is better than any other way. just adding my 2 cents

 

 
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