I work with an apprentice and I thought I would pass along some things that have helped him.

1. I have started using a procedure that really helps with feeling the filler. A lot of what you are feeling on the final stages finishing off filler are scratches or irregularities in the surface texture and not highs or lows in the filler. When block sanding you are of course going in a number of different directions, this causes an irregular texture that can be felt and throw you off, good and bad ways. You could "think" there is some high spot there that you need to block (and you continue sanding) all the while it was perfect and you were feeling this texture of scratches from previous blocking.

So, what I have begun to use on a regular basis is a piece of 400 and sand the panel in a circular motion to "kill" all the irregular scratches from the blocking.

It works like a charm and you can REALLY feel what you have. The bad part is (or is it good) that many times it is not done and what I thought was perfection is far from it. All I know is now the job goes to the paint dept I KNOW it is right.

2. Be sure it is stripped out far past your filler work. If you are applying epoxy primer to the metal prior to filler work this tip still applies. You need to be way out past your dent with the epoxy. On most restoration projects like you guys are doing this is a moot point of course being the whole panel is likely stripped and possibly covered in epoxy primer. In this case you don’t strip the epoxy off. But you can still use the concept of what I am referring to in that you need to you’re your filler work well beyond the dent. To have a skim coat of transparent polyester putty out over straight metal is no big deal. You need to be feeling METAL and filler only. If you have a poor feathered paint edge that is going to throw you. You are going to need to feather edge it sooner or later, you might as well do it as you do your bodywork. I will always cut the paint off the panel for the repair with 80 on a "hog" but not getting into the metal much if at all. Just cut thru the outer paint layers. Then I switch to 120 on the DA and feather it out further. This way, there are NO 80 grit scratches that could ever be on the feather area where filler isn't covering. If you have metal (or epoxy primer) with 80 grit scratches it MUST be covered with filler or putty (polyester of course). So, if you feather edge out past where you are going to apply filler with 120 you are safe with primer going over that. I rough cut the filler as per my “Basics of Basics” on plastic filler and feather out the paint even more if needed. All I know is when that skim coat of polyester putty is applied it is completely covering any 80 grit scratches in the roughed out filler AND the surrounding metal or epoxy primer.

3. You don’t need to cover the whole area in one application of filler or polyester putty. If you are having a hard time to get it all out smooth before it “kicks”, then break it down into manageable areas. For instance, you would apply the filler or putty only below the body line of a dent that covers above and below the line. Then after you clean your tools and mix up some more and apply the filler to area above the area above the body line. You can even apply filler over the filler before it is sanded. Say you got your filler on and see that there was an area you didn’t apply quite enough, just mix a little more and apply it over the thin spot of filler previously applied. As long as you do this within a short period of time before the filler is totally cured it will be just fine.

Even if you don’t have a body line or some other break off point you can apply the filler feathering out the edge thin with pressure on your spreader and then continue the spreading with newly mixed filler starting at that thin feather edge until the whole area is covered. It isn’t a big deal that the edge is feathered out thin, but it helps to do that and start the additional filler back onto the first section over the feather edge a few inches so that you don’t have a big line at the meeting point.

4. The absolute biggest trick in doing filler is getting the surrounding areas or any area where metal is showing to be transparent. I can’t stress that enough. If your filler ends abruptly and there is shiny metal right next to it, there is a high spot there. The filler should be transparent as it feathers off onto the metal or over metal that “pops up” in the filler. If you work from the outside (straight metal) in towards the center (damaged metal under the filler) and the feather edges are transparent you are going to get the thing flat.

Brian

great info, thanks for sharing. another good tool that is a MUST for work like this is 3m, dry guide coat (upol makes it in a spray too) when martinsr referred to removing all the 80 grit scratches with 120, if you put dry guide coat on the 80, when you sand and the black is gone that means there arent any more 80 grit scratches in you work. this isnt as important for people that have been doing it forever like him, but for us newbies its a necessity. almost all primers fill 120 grit scratches, so you wont have any shrinking later. this is especially important when you're using cheaper primers. i am working on a hood right now (51 chevy with shaved seam) that needed a whole skim coat of glaze. i finished the glaze in 80 and threw on some primer before i went to sleep. it wasnt ready for primer, but it was close enough to block out this morning and prime again. i'm using chromapremier 2k urethane primer, its like $280 a setup, it filled the 80 grit scratches with 3 coats no prob. BUT yesterday i was working on an 40's oven doing some body work, using the nason $90 gallon urethane primer. there is no way an 80 grit scratch is going to get filled, maybe at first, but after a month of the oven sitting in the showroom the scratches will start to show. dry guide coat is simple insurance to keep you from redoing things a year later.

And I have to tell you Sean, if you have a large area like that with filler and have to leave it in 80 (very common if the panel flexes a lot) using polyester primer is a super way to go. Then you aren't really asking a "primer" to fill those 80 grit scratches because the poly primer is literally a sprayable filler.

Brian

i didnt think about using that.maybe i should've. i think i have a quart of the evercoat stuff lying around, but i'm pulling a showcar repair in two days. its fkin stupid- the motor burned and took the firewall and hood with it. had to strip someone else's filler off the hood (bottom and top) and repaint/buff by tomorrow morning at 7. i just wetsanded the bottom of the hood and its drying. hopefully the 7600 turbo clear will let me flip it over and sand the top in an hour. he's leaving for a show or something monday evening. brought the hood to me thrusday night. i'm scared of trying to rush that polyester primer like i can with the urethane and my curetec infared light. pics when i come down off of this adrenaline rush sometime tomorrow..........

In the future do a little test with the Polyprime. It WILL be cured THRU much faster than urethane. The urethane will be sandable sooner, "dry" if you will. But fully cured enough that you could turn that hood over, polyprime will kick urethanes ars.

It is a super product for doing those large flexable panels like a hood. Rough the filler out in nice sharp 36 grit so you don't have to press much and then apply a few coats of polyprime over that just as you would a skim coat of polyester putty. It is much easier to work with than putty. Block that with nice sharp 80 and apply another coat. Then sand that and paint or sand it and apply a urethane to match the rest of the car and sand and paint that.

It is really a super product, IF you need it.

Brian

what brand is polyprime? i've used the evercoat stuff and the 3m stuff but i dont recall what they were actually called.

a trick an ol timer told me once was to put a paper towel/napkin between your hand and the panel when feeling for hi - low spots ... he said that way you feel the panel and not the filler or scratches

an old guy showed me that trick but he used a plastic bag

"Polyprime" is a name that PCL uses but I wasn't even refering to it. I was refering to ALL polyester primers, sorry.

I have tried the paper or towel trick and it has never worked for me. It is a "barrier" or "Block" from REALLY feeling the panel. I know lots who like it but it isn't for me.

Brian

Amen Shane, I was going to say the same thing for novices that have not "feel" for the bodywork. That is how I was shown to feel my work almost 20 yrs ago and it still works when I show up and coming bodymen.

an old guy showed me that trick but he used a plastic bag
makes sense ... and I bet they would "slide" better than a paper towel or napkin ... I need another user for all of those Wal-Mart bags anyway. :lol:

closing your eyes helps more than anything. it keeps you from "thinking" that the panel is straight, you just concentrate on whether you hand moves over a high or low spot.

Also if you are a novice bodyman, always block your work in 45 degree angles of the panel so that you take all of the contours of the panel in to effect. Use the 3m powder guide coat to help you see your work.

actually you want to block in an "X" fashion ... at 45 degrees.

There is a lot of very good ingo on how to sand bondo on a panel. Is it ok to put more bondo on dried bondo like say if you sand too much. Also on a curved or rounded area what is the best tool to sand with?

It is fine to put filler over other filler, however, I just don't feel right unless I scratch it a little first.

I personally use regular flat blocks on curved panels. I look at a curved panel as a "curved flat". I know it sounds crazy but that is how I have been doing it for years.

Brian