applying filler

You can start by mixing your filler, after the panel is clean and blown off. Do no mix the filler on cardboard. The cardboard actually absorbs the hardener and will reduce the amount mixed into your filler. The usual is a one inch strip of hardener to each golf ball size of body filler. Mix well, if you are using your applicator to mix, make sure you wipe it off before applying the filler. Do NOT whip, the filler while mixing. Press it into your filler board while mixing. If you whip it, you add air bubbles to the filler that will sand off and become pin holes. After mixed, make your first pass of filler. This first pass is called a "tight" coat. You put a very thin, even see through coat of filler on, pressing it down hard into all the sand scratches and bumps. Once your tight coat is on, then apply a second heavy coat... this is all done at once with the first mix. Fill the area beyond any damage or weld areas. Once the top of the filler becomes tacky you can lightly hand sand it to help sand faster... then let it dry and finish blocking. I suggest you use 36 grit on the fiber filler. P.S. there is no point to blocking your fiber filler... it is just there for heavy filling... you can grind it down with a sander to help speed up the process. Always block your body filler too. Using a block that is bigger than the damage area will help get it straight... as well as using a coarse grit paper. The faster you cut the filler off the straighter it will be.