You want a perfectly straight car, to be able to sight down the side of it, and not see a ripple anywhere, and not even be able to tell where the panels start and stop.
Getting to that perfectly straight car requires using body filler. How much of it should you use, and how much is okay to use?
It is ok, and actually encouraged, to skim every panel with filler. Once in a while, a panel might be nice enough to prime, but that is rare. These are usually roofs and portions of hoods, very rarely the sides of cars.
There is always a small amount of ripple in a panel, even if it seems nearly perfect. When you skim it and block sand it with True Blox, you will find that it picked up plenty of areas that needed filler. Also, the shape of the whole side needs to be made consistent, and the entire side needs to be block sanded together. That requires filler on the panels to get the body dialed in.
Primer doesn’t actually fix very much. It makes for poorer quality, and takes more time, to just prime something, only to discover it still needs body work.
The point of this is to create body work that is distinctly better, not just good. There is a clear difference when the vehicle has been body worked and completely blocked out.
Filler is ok. There are a lot of additional tips in the body work section of this website to help with filling and blocking.
The picture below is a great example. This car is one of the straightest body I’ve seen, the doors were nearly perfect. As you can see, when it’s body worked, it actually needed it, and is far better for it. Built by Ring Brothers
Be sure to check out our sanding block sets. They are an important part in getting your body work really dialed in.