Well, I received a shock the other day that blew me away. I was telling my employer about the method for filler work I was teaching an aprentice and he said "That is your first mistake, that is not company policy" HUH? What in the living hell are you talking about? This is what I was thinking of course, not actually saying .
He says that you are NEVER to sand plastic filler with anything coarser than 80 grit paper. Even if you are going to apply more filler over it! This was taught to him he told me in an ICAR class or something on using body fillers. And not just one class but many. I have been to a heck of a lot of classes and never heard this, or at least I didn't want to.
The reason being that if you leave these 40 grit scratches in the filler when you apply the next coat of filler the scratches are so deep that the filler won't go down to the bottom of the scratch. This will leave a little pocket of air at the bottom of the scratch that will expand or and cause swelling, or shrink down as more solvents are added over the top in the primers and paints.
Now, this IS the reason for sand scratch swelling or shrinking with primers and paints, but I had never heard it being an issue with plastic fillerers which just don't shrink to any degree.
Why in hell we have 40 grit paper in the shop is beyond me if he didn't want us to use it. 8" for the killer, 8" for the hog, long board, stick-it non stick-it, we had it for the DA, for every tool we use, we had 40. Ok boss, we won't use 40 anymore. I put a note up for the salemen from the paint store DO NOT stock 40 in anything any longer.
The last shop I worked at used nothing coarser than 80 and we got along fine so I thought, no problem, he's the boss, no 40, done deal. Another tech went nuts so I went ahead and called Evercoat tech, sure enough, they say not to use anything coarser than 80, for the reasons he laid out.
So guys, if you want to go by the manufacturers recommendations.....nothing coarser than 80. I hardly ever use the 40, but on those quarter panel length filler jobs it will be sorely missed by this guy.
Brian
He says that you are NEVER to sand plastic filler with anything coarser than 80 grit paper. Even if you are going to apply more filler over it! This was taught to him he told me in an ICAR class or something on using body fillers. And not just one class but many. I have been to a heck of a lot of classes and never heard this, or at least I didn't want to.
The reason being that if you leave these 40 grit scratches in the filler when you apply the next coat of filler the scratches are so deep that the filler won't go down to the bottom of the scratch. This will leave a little pocket of air at the bottom of the scratch that will expand or and cause swelling, or shrink down as more solvents are added over the top in the primers and paints.
Now, this IS the reason for sand scratch swelling or shrinking with primers and paints, but I had never heard it being an issue with plastic fillerers which just don't shrink to any degree.
Why in hell we have 40 grit paper in the shop is beyond me if he didn't want us to use it. 8" for the killer, 8" for the hog, long board, stick-it non stick-it, we had it for the DA, for every tool we use, we had 40. Ok boss, we won't use 40 anymore. I put a note up for the salemen from the paint store DO NOT stock 40 in anything any longer.
The last shop I worked at used nothing coarser than 80 and we got along fine so I thought, no problem, he's the boss, no 40, done deal. Another tech went nuts so I went ahead and called Evercoat tech, sure enough, they say not to use anything coarser than 80, for the reasons he laid out.
So guys, if you want to go by the manufacturers recommendations.....nothing coarser than 80. I hardly ever use the 40, but on those quarter panel length filler jobs it will be sorely missed by this guy.
Brian