Body Filler.

[ashlee205gti 1]

Ive been using a lot of this stuff lately and im just after some tips. Whenever i use it i cant seem to apply it in one smooth 'swipe' i always seem to get a line running through it or pin holes which means waiting for it to harden, sanding flat and doing it all over again to cover up any pin holes, lines etc. I use the correct mixture of hardener (i think) until it turns into a nice pink colour and then attempt to apply flat and smooth but it just seems to leave holes on the surface, its a bit hard to explain in words. Its as if its 'tearing' from the applicator onto the bodywork leaving a very unsmooth finish and thats whats causing the pin holes.

[allanallen 528 2 Cars]

dont try to put the filler on at the level you want it make sure it sits proud off the panel plenty, it takes longer to sand down but is a better more even finish

[sherly 0]

Use knifing stopper (smooth fine filler) once you've got the required profile with P38. This'll fill the tiny holes and scratches. Filler primer also helps.

 

Mart

[Beastie 1]

In this weather - I'm not that surprised if you are having some difficulty! If you were heating the workshop to an ideal temperature then you would probably not have posted this - you would have been too busy out mugging people to pay the heating bills ;-)

 

I'd suggest storing the filler in the house for at least 24 hours before you use it and also gently warming the area to be filled with a convector heater. The filler will then be much easier to apply. Then go for the stopper already suggested - avoid single pack "ready to apply" stoppers including ones labelled as "cellulose stopper" "knifing putty" or "knifing stopper" like the plague: They have the annoying habit of shrinking long after the repair is completed leaving unsightly depressions in the paint. The ones to go for are 2 pack stoppers - they're not iso cyanates - 2 pack means that they come in two components of stopper and hardener just like ordinary body filler does. Top Stop Gold is readily available and works well enough.

 

Hope this helps!

[Paintguy 0]

I'd like to reinforced the point made by Beastie, and add a few of my own.

 

Temperature is definately a big factor. The filler becomes much less pliable when cold, making dragging and pinholing much more likely. Make sure you're not mixing 'bubbles' into the filler too. Always mix in your hardener with a spreading motion, pressing down hard to force out any air.

 

Although not relavent to this question, make sure you're not adding too much hardener either. More is definately not better! Although it might dry a few seconds quicker, it'll set like concrete, making it much harder work to sand down. It should sand down easily, almost like grating cheese at first, then getting a little harder as the filler fully cures. Exessive amounts of hardener can cause problems much later on too, as it can leech through to your paint, leaving a 'stain'

 

I'm not one of the 'pile loads of filler in and carve it to shape' bunch either. I find it much quicker and better to build up the filler in layers (except on really small/shallow ones of course). Trying to put too deep an application on in one go can also cause it to tear out of the dent, in the way you describe.

 

I would start by putting a very thin skim in the bottom of the dent first, pressing really hard to ensure good adhesion, and force out any air bubbles, then go straight over this with a thicker application, just enough to fill the dent. When this is dry, it should only need a very quick sand to get it to a reasonable shape. If you have any low spots that need more filler, or the whole thing is a little low, add more filler, but only where needed.

 

After another quick sand, you should then have the dent almost perfectly filled and shaped. This is where a final skim come in. This should be a very thin skim, extending a few inches past the edges of the repair, just to even everything up, and feather it out. Leave this last skim a little longer to dry, so the edges don't peel back as you sand it, and you should end up with a very professional repair With practice, just about any size and shape of dent can be done with just 2 skims.

 

Don't try and sand your filler with too fine a grade of paper either. A fine grit will tend to ride over the humps and bumps, instead of cutting nice and flat. I personally sand with 80 grit at first (40 if it's a really bad dent), working down to 120. My final skim is sanded with 120, working down to 240.

 

Your final skim can be done with regular filler, but 2 pack stoppers are much better for this kind of thing. They are ground finer than regular filler, and thus spread and feather out much easier. As mentiond above, steer clear of the one componant stoppers, as the are basically just thick primer. They will absorb the solvents from whatever primer you put over them, and swell up. You then sand your primer nice and flat over the top of this swelled up stuff, only to have it sink back at a later date as it finally loses the solvents and shrinks.

 

I have used Beasties suggestion of Top Stop Gold for many years, and have found it a very good product, although I've recently switched to Roberlo Multiextender, as it feels a little finer and easier to spread, and also sands slightly better too.

 

 

I've gone on for way too long, and covered things you didn't even ask about, so I'll go and get back in my little box now