Body Filler advice for a newbie

  1. blitz61 New Member

    Messages:
    2
    Location:
    Essex
    I had a complete sill replaced and to aerosol body colour after. I'm having a hard time trying the apply the body filler on the weld seams especially in the door shuts where my applicator is too wide to uniformly spread the filler. Also some areas there is a slight step between the body and the new panel which makes it even more difficult.

    I have sprayed filler primer so you can see the results and how patchy it looks.

    Can anyone give me any tips to make it an invisible repair?

    I'm using P38 Body filler.

    Thanks

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  2. Parm

    Parm We Will Do Whatever It Takes

    Messages:
    10,945
    Location:
    Towcester
    You need to grind / DA / by hand sand the high spots then feather out the filler over a larger area when applying

    Then sand back

    It’s a PITA on tricky areas like that as it’s difficult to get in a machine which will make things quicker

    One of those mini DA’s will be a god send if you have one
     
    fizzy and barking mat like this.
  3. qwakers Member

    Messages:
    318
    Location:
    cornwall, united kingdom
    two words...

    dolphin glaze.

    can get it from halfords, you need to buy hardener too.

    its for exactly that fine work.
     
  4. qwakers Member

    Messages:
    318
    Location:
    cornwall, united kingdom


    watch that. it should give you a idea ofhow to.
     
  5. Dcal

    Dcal Forum Supporter

    Messages:
    1,826
    Location:
    Antrim Northern Ireland
    Are the welds proud of the surrounding metal?
    Use a straight edge to check.

    Don't try to get the filler on smooth and level in one operation.
    Apply too much and sand it down to the level you need. As your technique improves you will apply less filler but for now just worry about getting enough on.
    Use sharp coarse 80 or 120) aluminum oxide paper and a flat block or sanding block to shape the filler to shape.
    If you use too fine a paper to try and stop scratches you will never get the filler level. When it's right take the scratches out with finer paper and the primer filler or stopper. (dolphin glaze as @qwakers said while I was writing this)
    Don't leave the filler too long (let it harden obviously) but the longer it's on the harder it is to sand.
    You can use round or shaped blocks to shape the inside corners.
     
    slim_boy_fat likes this.
  6. Reman

    Reman Member

    Messages:
    89
    Location:
    Bristol, UK.
    Body filler really needs to go onto bare metal or you usually get a sort of "Halo" effect around the edges.
    The trick to getting a good finish in a complex shaped area like that is to use ANYTHING you have that's around the right size as a sanding block. A few stubs cut off different diameter broom handles can work well (You can also use the flat ends to sand into flat bottomed dimples like you've got in your last picture). I've used spray paint cans, screwdriver handles, AA, C AND D cell batterys........ ANYTHING the right size !
    For the final sanding I've found wrapping some wet and dry around a piece of "Pool noodle" can help even out any little lumps and bumps. It also works out way cheaper than using those foam sanding blocks.
    Personally I find it's better to build up several thin layers of filler to get the exact shape you want rather than to go all out and glob on a ruddy great scab of it and spend the next week sanding it back. For the last application where you're only really adding a small amount to low spots I usually put on some rubber gloves and smear the filler where I need it with my fingers. It's always felt a way more controllable way to only add it where it's needed.

    Hope that helps.
     
    slim_boy_fat and Gragson like this.
  7. blitz61 New Member

    Messages:
    2
    Location:
    Essex
    Thank you for the quick reply guys.

    The welds are mostly flush its just there is a step between the panels. I must spent the whole day trying to that section. I will report back.
     
  8. keithski122 Member

    Messages:
    983
    uk
    You can cut you filler spreaders down in size if they're the plastic ones, also a big mistake is to use too fine a paper to start with for shaping.
     
  9. Domdom Forum Supporter

    Messages:
    223
    Location:
    UK, Warwickshire
    This !! And you can warm up the unmixed P38 by standing the tin in a pan of hot water, makes it go runny and easy to apply with fingers. Use a latex glove. Slightly less hardener can be used as the heat makes it go off quite rapidly.
     
    Reman likes this.
  10. barking mat

    barking mat Member

    Messages:
    2,387
    Location:
    Brittany
    Sand paper mate!

    Make a former if you need to.

    Welcome to the forum.

    Tidy work!
     
  11. Dcal

    Dcal Forum Supporter

    Messages:
    1,826
    Location:
    Antrim Northern Ireland
    If it's not below the surface, hit it with a hammer until it is.
     
  12. Matchless

    Matchless Member

    Messages:
    714
    Location:
    Essex UK
    for large areas use a number plate as a spreader,
     
  13. jsf55

    jsf55 Forum Supporter

    Messages:
    466
    Location:
    Sunny Swansea
    Old credit cards can be a god send, easily shaped to fit the contour your trying to achieve
     
    slim_boy_fat likes this.
  14. pedrobedro

    pedrobedro Man at Matalan

    Messages:
    10,243
    Location:
    CX Derbyshire
    Start with 80 grit aluminium oxide paper and fill it again to take out the scratches, be patient and work through to about 320 grit to finish it off. Keep filling the nicks before you finish it off with primer filler. Don't try to do it all in one go.
     
  15. Reman

    Reman Member

    Messages:
    89
    Location:
    Bristol, UK.
    I've been using P38 for decades and I actually didn't know you could do that. Might be a useful trick when trying to fill in all those tiny little pits that get left behind when you've chemically stripped heavy rust off of thick metal components.

    Back in the early 90's a mate gave me a ruddy great can of the stuff (2 liters I think) as a joke birthday present. As I was driving a rusty Fiat 127 at the time he created a quite convincing "Genuine Fiat Parts" sticker at his work to wrap around the tub. I remember on the back he'd printed a "Model compatibility list" that consisted of every 1970's and 80's Fiat ever made, Compleat with the typical number of tubs required for that car........ We were quite a creative group of p**s takers back then. LOL !
     
    Cobbler, blitz61, stuvy and 2 others like this.
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