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body filler over primer?

Discussion in 'Body / Exterior / Interior / Cosmetics' started by ssl2k, May 9, 2004.

  1. ssl2k

    ssl2k Senior Member

    Alright, i have a 91 crx si and it has well... lets say a lot of body work to do. Rust repair, door line filling, body kit fitting+molding, etc. Now, I am planning on using kitty hair(short strand waterproof body filler) for almost all of the body work, fixing the door lines, etc. then putting the lightweight body filler over that. then topping it off with finishing coat. I do not plan on using regular bondo at all because the crap sucks. period. it cracks and just sucks. I want to take off all the old bondo and then primer the whole car, then start doing all of my body work.

    If I spray primer, Do I need to sand it off before I can put more body filler in, or can I put body filler over the top of the primer? Without having paint lift or anything like that?

    So here is the visual of the layering

    Metal / Fiberglass
    body filler
    more primer
    body filler
    lightweight filler
    top coat

    Basicly, will the body filler stick to the primer just as good as to bare metal?

    ..or do I need to sand the primer off and put the body filler on the bare metal?

  2. ssl2k

    ssl2k Senior Member

    Also, what are you're opinions on the quality of the various body filler?

    regular bondo
    light weight body filler
    short strand body filler
    long strand body filler
    metal 2 metal body filler
    top coat / finishing coat body filler

    what are the pros/cons about each and what are thier intended purposes?

    Am I doing it wrong by using the light weight body filler over the kitty hair/ short strand filler ? What is the strongest? etc?

  3. BodyDroppedNikes

    BodyDroppedNikes ...PENDEJO....

    usually you put body filler on THEN primer, but yeah body filler should stick to primer.
  4. driver1

    driver1 Senior Member

    no u cant put the body fller over the primr if you do not snd it first....body filler sticks bets if the surface has been sanded with 80 grit first. What you want to do is ridiculous and not necesarry. sand the surface to bare metal where you want to put filler (grinding it works best/quickest). then apply your fiberglass filler, shape it fairly well using nothing finer than 80 grit, then put your plastic body filler over it. Then you can use a finish filler which is ussually polyester and only for filling sand scratches. THEN you can primer it. What you want to do would make for way to much product on the car and it would chip easily and just make fior a shitty overall and would not last long at all. then apply your paint over your primer which you will want to sand with 320 to 400 but if you use 320 you will need some sort of sealer to fill the sand scratches
  5. ssl2k

    ssl2k Senior Member

    Well, there is going to be a huge amount of filler on this car...it was rear ended hard core so the whole backend was crunched..not to mention a lot of it is rusting out. I welded in some metal but then it rusted on the inside of it because of not being sealed. so yeah...there is a lot of filler on this car already, and the paint is pretty shitty.

    I want to basicly strip down the whole car and remove all of the rust, old sheetmetal, and fiberglass, and bondo.

    Rebuild the holes w/ new fiberglass, then finish it with the body fillers..

    The reason why I want to primer it then fill it in is becuase, I want to use a paint stripper and completely strip the car down to bare metal, then cut away all the old shit, then primer it so it wont rust...then start the build up of new fillers/fiberglass.

    I guess I can do the stripper thing + primer but whenever I add filler/fiberglass I'll just grind down the area.

    btw, driver1, what is your opinions on the different types of fillers / qualities?
  6. cheese9988

    cheese9988 Senior Member

    At the very least sand down the primer and then apply the filler. That way the surface will be somewhat rough and will give the filler something to stick too.
  7. ssl2k

    ssl2k Senior Member

    Yeah I think that I'll paint strip it, remove the old filler / rust then prime the whole thing, then from there, when it comes time to work on an area, go to bare metal
    then do my work for the area...
  8. MikeBergy

    MikeBergy Blah blah blah....

    sounds like a lot of work. I hope you got the car for free. :)
  9. ssl2k

    ssl2k Senior Member

  10. hcivic.com

    hcivic.com Senior Member

    bonda and kitty hair stick way better to bare metal. get the car media blasted its only 150 and will leave bare metal. then cut and weld in patches, and seal the inside with rust paint. and aply filler over tha metal you should not need kitty hair if you pull the dents and get the sheet metal close. unly use the kitty hair to mold the kit on.
  11. driver1

    driver1 Senior Member

    i use martin seniour/napa micro lite lieghtweight body filler and matin seniour fiber strand for fiberglass. If you do not have a napa locally evrcoat is a good brand to go with as well, and most paint supply stores will carry that. just be sure to get a good leightweight filler. Also unless you have to put the car outside alot i still would not recommend priming it then starting your body work just strip it then do your pulling and mudwork then prime the whole car. The less prdut you put on a car the beter the result will be the less it will chip and the longer it will last.
  12. tab

    tab Super Moderator


    I think this is important, for more than one reason.

    If you fill more than about 1/8th of an inch thick, that spot will look different from cold to warm days. Body filler does not expand and contract at the same rate as metal. Also, if it is too thick, it will probably fall off or crack eventually. Never use body filler alone to span any gaps. It will crack out for sure. That was the biggest mistake I ever made on my first paintjob. Luckily, I was willing to make mistakes to learn :)

    7 years later, I've picked up a few tricks. B)
  13. ssl2k

    ssl2k Senior Member

    What do you suggest for filling body lines then? They are pretty figgen deep..
  14. tab

    tab Super Moderator


    I am especially speaking of body lines. Body lines look terrible filled with body filler. One minute they are perfect, ten minutes later they look terrible. I am speaking in person about a S-10 pickup as an example.

    Metal on metal is always the best filler. If not, pulling the existing metal to surface level is best. After that, I would use a fiberglass, with a lightweight filler as the absolute surface smoother. The less filler, the better.

    When I speak of my problems, I was trying to smooth a fiberglass body kit into a steel body. Filler cannot be used in itself.

    Filler in just the body line is acceptable, but very noticeable.

    Ask your local paint store for a filler that is as close as possible to steel for expansion and contraction.

    I always look to those that know more than me for info. That's how I found hondswap. I know Driver1 knows more than me, maybe he will add his two cents.
  15. ssl2k

    ssl2k Senior Member


    There is no way that i can really get around doing this any decent way. On every peice of the car there is going to be body filler. it was rear-ended, and then rust in the wheel wells, rust of the sunroof, rust on other spots. etc. it is bad... basicly,t here is going to be a thin layer of filler over the entire car. i know that is an extremely bad thing to do.

    I talked to an older guy at the local napa store and he said that it could be possible to take the car and have it pellet blasted, then cut the rust out, and then spray the car with an etching primer. He said that the primer will stick to the metal better than body filler, and then the body filler will stick better to the etching primer. making it a win win situation.

    driver1/tab what do youy think about that?
  16. swanny

    swanny Senior Member

    Media blasting is awesome but expensive, if you can afford it i would go that route.
  17. tab

    tab Super Moderator


    I think soda blasting is one of the best for cars. The soda is a base, and at least for a short term helps hinder rust. Also, it won't dig into the metal as bad as sand.

    Any form of blasting would work, but how bad is the rust? Is the whole car rusty?

    If it is, then yes, I'd blast it. It is an effective way to knock away rust, and not mess with chemicals. Then cut out the holes and weld in new pieces, fill the low spots and use your etching primer.
  18. ssl2k

    ssl2k Senior Member

    my buddy's dad does blasting and i can have it done for free....well kinda, a case of beer and me doing it myself :).

    but would using chemicals + a grinder pretty much do the same thing ?
  19. driver1

    driver1 Senior Member

    Balsting the car is not a bad idea especially if you have the means to do it yourself for free. Now as for the old guy at napa that told you about the etching primer, he doesnt know what he is talking about. Filler will NEVER stick to anyhting better than bare metal, now when i say bare metal i am referring to something that has been sanded or grinded with nothing finer than 80 grit (I grind the spots im goin to fill with 36 grit before i spread my filler). Now as far as the filer goes for body lines and what not i strongly suggest welding in sheetmetal in any or all areas you can in order to get the surface up to the same level as the rest of the body. Then use fiberglass first then your regular plastic filler. For your dents and damaged areas like wherer it was rear ended you need to have them pulled or pull them yourself if you have an idea what your doing. You need to do this in order not to use to much filler. as far as the rust goes like i said earlier you want to cut it out an inch or so around the visible hole and rust area then weld in a patch, grind the welds fiberglass it, then use your filler to smooth it nicely. Now if your going to prime the whole car might i suggest getting something for a GOOD high build primer, this way with 3 coats you will fill alot of the imperfections and not have to use so much filler. After priming thw hwole car you want to longblack the entire car with 320 or 360. Longblocking it will keep you from getting that wavy look down the side of the car when you look down it which is result from just hand sanding before paint. be sure to longblock the hell right out of it until it is good and smooth and if you use 320 which does sand nicer and not clog up as much then your gonna need to use some sort of sealer to hide the fine sand scratches(sealer is good idea anyhow on such a project). hopefully that answers most of what you need to know and if not ask again and i will offer all advice i can give .
  20. ssl2k

    ssl2k Senior Member

    Yeah that helps alot...

    just a couple of things....

    the back end was rearended as you know, then it was already pulled, and it rusted from the inside, and then it make the bondo start to crack. so there is rust coming through the puller's holes and stuff. ...I need to go abck in there and clean that all out. I re-constructed the back corner where it was all rusted out before, and the rust started to rust from the inside out...I'm guessing i should probably seal that with rubberized coating? or something like that?

    Will body filler attach to fiberglass just as good as bare metal?

    Instead of filling in the door lines w/ welded sheet metal i was thinking about building up the surface w/ layers of fiberglass. I have gotten okay with laying fiberglass from making a box + misc projects around the car. What do you think about that ? just making layer after layer along the body line until it is build up to almost the top? Would that be better than pure body filler? - How will this hold up against cracking , etc?

    And in the rearended area, Where the holes are from the puller, after i remove the rust w/ a wire wheel, would it be good to "seal" the holes with fiberglass resin? or possibly fill in all of the dents w/ fiberglass resin? then go over it with filler?

    and , i'm still a bit unsure about which is exactly best for each application....when it comes to fillers

    metal2metal = best for pretty much anything...

    kitty hair = only good for molding the body kit?

    and what about lightweight filler?

    I mean, in the deep spots am I going to want to use kitty hair where there are a bunch of dents? or regular filler? and lets say on the door lines, i get them almost up to snuff w/ fiberglass, will i want to use the lightweight filler instead of the regular filler?

    alos, why not just use like strictly kitty hair / lightweight filler? e.g. use the kitty hair to get it up to where it should be, then lightweight to finish it off, then maybe a top coat?

    or will i even need a top coat becuase i am going to be using a high build primer which will take away pretty much all light scratches...

    thanks again..this is really helping me a lot

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