View Full Version : Filler & Primer
08-19-2007, 02:36 PM
Guys,new to this forum and new to doing body work.A few yrs ago I repair and painted my first small truck.Paint job look ok for someone who knows nothing about auto painting or minor body work.Well after a couple of yrs the bondo in some area's have chip or has come loose.What went wrong?I don't want to make this mistake again.Now I have an 82model jeep that I am going to try to get it back from the dead.My question is (keep in mine this is my second try)is it best to apply filler over primer then spray primer over the filler then paint, or sand down to metal,apply filler,primer,paint.On my jeep,I will have to weld new metal to area's,and other parts of the jeep will have to sand then primer.Could ya'll suggest a book about the basic's of how to prepair an auto for painting.From shinnie metal area's,to faided painted area's.This is just my first questions with more to come,I'm moving at a snails pace.Thanks CJ Courtney
08-19-2007, 02:39 PM
Could be alot of things. To many to describe. Maybe you should look at the tutorials provided by the site. It will help a great deal and you'll thank yourself later.
08-19-2007, 06:29 PM
like what showcar said, there could be a lot of reasons why the plastic didnt hold. i am a firm believer that plastic should be applied to bare metal, not over primer. the filler could have come off because the surface wasn't properly prepped, i usually sand with 80 before applying filler, a lot of people use 36 grit grinding discs, either way theres gotta be something there for it to grab onto. also filler shouldnt really be applied more that 1/4" thick any thicker can cause cracking, moisture could have also gotten behind the filler, did you fill any holes with it? any welded seems should be coated with water resistant filler before regular filler
The adhesion of filler to the metal is a mechanical process and if the metal was smooth then the filler can easily lift off the surface. The best way to insure good adhesion is to grind the metal using a 16, 24 or 36 grit grinding disk then push the first pass of filler into the scratches before applying heavier coats. This is like priming the surface for the filler and helps it bond well to the surface.
08-20-2007, 06:11 AM
The reason why the bodyfiller came off is either because you made it too thick or you mix it well.If you put too much hardner making it to dry faster it causes bubbles. Inside the bodyfiller is still hot which makes the bubbles ris and it causes pinholes If that jeep was mine id take 24 on a DA and go over the the whole car then id put 24 on a board just to hit the spots that i missed. Now being that the metal is bare and clean you wanna shoot epoxy primer. Give it about 2-3 good coats then block it down.
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