Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (
-   Body - Exterior (
-   -   Why do I struggle with bodywork so much (

Arrowhead 08-07-2007 06:24 PM

Why do I struggle with bodywork so much
I have the ability, I'm a pretty smart guy, I can build motors, program EFI, weld body panels on, do a decent paint job, wire my own electrical systems, yada yada yada, but for some reason, bodywork and bondo escape me. I can't even get my buds to come show me a few tricks. (I know why they won't come over, it's because they are afraid they will get stuck doing it, some buds they are :) ) I have two sisters that are artists for crying out loud. You would think I could spread some putty and smooth it out. Have the same problem with taping drywall, put on a gallon, sand off two.

I guess I'm just a big whimp. I really don't have the stamana for sanding, never did, even when I was a kid and mostly in shape. So I just get frustrated.

I know, the bodywork is what seperates the "WOW! LOOK AT THAT! :D " and the "wow, look at that :rolleyes: .

I've read the magazines, the forums, talked to friends, talked to experts, etc, etc.

I have to get through this and I will. Maybe it's just the summer heat, I don't like working in the summer either.

Sorry for the rant, but I do feel better now. If anybody want to join my pitty party, then by all means, log on! :)

MARTINSR 08-07-2007 06:49 PM

"Basics of Basics" Plastic filler ("Bondo")
By Brian Martin

What ever tools you use the trick is to not add the last "skim coat' till you KNOW that it is all you need. Don't try to block out that first coat, just use it as a base for the LAST skim coat.

I was taught this procedure after doing bodywork for a number of years and it really works well:

Just apply a nice coat of filler (what ever brand, whatever style, we will put that aside right now). Cut that coat NOT to make it perfect, but to get the basic shape and filling you need as a base for the skim coat. You can cut it with 36 40 or 80 depending on how big the area you are working is. In other words, if you can cut it fast with only 80 then do it. But I would say that this would be limited to an application that is no larger than about 8 inches.

If you happen to have a few high spots, see if you can tap them down.

If you have a few low spots add a bit more filler to ONLY those spots.

Re-cut these last low spots you have just filled with the same grit you have been using (most likely 36).

If you now have a surface that ONE skim coat will fill, then apply it. If you don't work with it a bit more, but NEVER add a little here or there and think you will finish it without a skim coat.

If you have a surface that is very close with only a few VERY MINOR low spots like poor feathering onto the metal, poor transitions from one application of filler to another, or from the metal that is "poking" up here and there you can do the LAST skim coat.

This skim coat is very important, you want it to extend over the COMPLETE area, this is well past the damage you have been working. Maybe as much as 3 inches past the plastic that you have applied to "rough" it out.

This skim coat can be regular filler or a polyester glaze like "Icing" or "Polyester glazing putty", that is your choice, I use both depending on the size of the area being worked. Do not use anything that doesn’t mix with a hardener. NO, “Spot putty” in a tube, only polyester putties or fillers. If it uses a hardener, it cures to a hard film. The “spot putties” stay soft and can become even softer when the solvent from the primer coats it.

You now run a block, long board, or hog even over this skim coat with a little bit coarser paper than you plan on finishing with to cut off the resin that has surfaced in the filler. I usually just use the 36 or 40 or whatever I have been on the "rough" work. BUT take CAUTION not to cut much off, you want to JUST take the very top, don't really sand AT ALL.

Now finish sanding with your longboard or block or hog or whatever using the finer paper like 80 on a large area or 120 on that small 8" sized area. Block it out to perfection with a nice feather edge to the surrounding metal.

I can't stress enough, the trick is to know when just ONE LAST skim coat will do the job. And apply it COMPLETELY over the surface. If you only one little low spot in the middle, DON'T just do it, skim the ENTIRE thing. You HAVE to have one LAST skim coat over the ENTIRE thing every time. If you get in the habit of this you will do it over and over on every dent you repair and find that you can do just about any dent with just two applications.

As you sand the filler let the board or block you are using run over the surrounding metal. If you only work on the filler you will sand it too low. You need to keep it as high as the surrounding metal, so use the metal as sort of a straight edge that you run the block or board off of.

Don’t worry if you cut through this skim coat here and there. In fact, you WILL most likely cut through. The point of that "LAST SKIM COAT" is that after you add it, you don't add ANY MORE filler. That "LAST SKIM COAT" is just that the LAST filler you add. If you hit a little filler below, or metal, that is normal and fine. The only thing you are looking for at that point is if the panel is FLAT. The filler skim coat is serving no other purpose than to finish you filler work, it is not a "sealer" or anything like that.

You can add fiberglass resin (“A” coat if you have a choice) adding the resin was exactly how I learned from the great Emery Robinson (my personal hero in the auto body world). But remember there was no products like polyester putties back then. When you add resin, that resin comes to the top of the film of filler. It is then something you have to deal with. The whole purpose of the SKIM COAT is to put a layer of filler over the top that is easy to block out with as little effort as possible. You want to be able to concentrate on making the panel FLAT not fighting with gummy resin, sand scratches and the like.

So the polyester putty though expensive is what I use.

How is this for an idea, a co-worker of mine showed me this very obvious tip. [img]smile.gif[/img]

Add pour-able polyester putty to the regular filler! What an idea! LOL A little pour-able squirted into the "bondo" really thins it out nicely.

The "LAST SKIM COAT" should be left to cure a good long time. Where you may jump on filler and sand it as soon as it is hard, the skim coat should be GOOD AND CURED for an hour or more. If you can of course, in the production shop you may not be able to wait that long. The benefits of the procedure will not be diminished.

A little added note, I have found that I don’t use 36 or 40 grit at all anymore. I went to work at a shop that didn’t use the coarser grits so I had to learn not to also. I have found that using just the 80 and then finishing the Skim coat in 120 or 180 works great, even on large panels.

At this shop it was the first time that I wasn’t doing my own primer work. This meant that I couldn’t “cheat” with a lot of primer and blocking the body work “one more time”. I found that I had to get the work PERFECT, then give it to the painter. I did this in an interesting way, I look at the last skim coat as even a more “final” step. I now look it as “primer”. You see I have used polyester primer, which is like spraying “bondo”. They are both polyester resin based and act and sand very much the same. So, I figured why not just “spread out my primer” as the skim coat! It has worked GREAT, the painter jokingly says, “do you think I’ll need to prime this or just paint it?” I tell him, “Just clear it, it’s a shame to hide that work under primer”.

This method has worked great for me, it’s more of a state of mind than a procedure.

And don’t be afraid to buy the best sand paper and use a lot of it, the cost of the paper will be nothing next to the time and muscles saved. Find the paint store in town that services the PROS the Body shops in town, that is were you will get the right stuff and the right info.

jimmy1 08-07-2007 06:58 PM

I know just what you mean arrowhead.I'd make this longer but I have to go comb the evercoat out of my hair and get the undercoat out of my armpitts!

hemi43 08-07-2007 07:13 PM

I'm self taught, and here's a few basics that took me years to figure out.
-If you have a panel with 2 or 3 small imperfections, don't try to fix them all separately. Skim the 2-3 dents with filler and sand smooth so as no metal shows through between them.
-Buy a gear driven mud hog!!! This has saved me countless hour of tedious sanding. With 40 grit paper this thing will get a panel perfectly flat.
-This is my best kept secret!! USE A SPRAYABLE FILLER ON YOUR FINAL COAT!!!!!!When you have your panel as straight as possible with body filler, a coat of this will make it perfect. I block sand this stuff with 100 grit, then finish to 320. My high build urethane then goes on top.I have pictures of my car that I just did at home on my website.If I can do it, anyone can. It's not rocket science it just takes patience.Dan

Arrowhead 08-07-2007 08:08 PM

OK hemi43, you convinced me. AWESOME job on the Dodge. That is sweet. I had been thinking the same size TT 2's as your running for my next project. Call me a sheep, but I have one of those 2 dr Fords waiting. (j/k, I know you didn't mean anything on your website. Glad you went all Dodge, that's how it should be)

Thanks, but I think i've read that a dozen times over the last few years. Maybe I'm just dense.

I think i'm going to go back to my slow and steady method. Just do small areas a little at a time and repeat with as many coats as needed. I had tried doing a "skim coat" and what disaster that turned out to be.

OneMoreTime 08-07-2007 08:49 PM

One of the things I have found is to use a light touch when blocking and longboarding. if the paper is not cutting get some fresh and if you push too hard you can deflect the metal to the point that the longboard is not telling you anything..


powerrodsmike 08-07-2007 08:54 PM

I don't know a whole lot about beating dents out or pulling racked cars back into shape, but I can shape bondo. 13 years in a 'glass shop doing a fair bit of tooling as well as sanding filler on one off shapes taught me a few things. I didn't grow up doing it, so starting at 24, it was not the easiest thing for me to learn.

Skim the whole area, don't try to just do small sections.

If I want to save time on big panels, I always use the biggest spreader that I can fit on the panel, even if it is a 4' aluminum straightedge, laid over to get it to curve. More than once, I have mixed up an entire gallon of filler and spread it like this. If you are tooling up for a 5 x 6 tonneau cover or a roof or a hood this gallon won't go far.

Yes to the "bondo hog" :thumbup:

Yes to shaping with 36 or 40 on a long board.

Yes to spraying polyester "filled" primer when you get it close.. I use stuff that can build .040"..that stuff makes a huge difference.

Get a can of guide coat black and use it. Even if you are still knocking it down with 40 or 80, on a big panel it will make a difference.

Close your eyes and feel the panel. a light touch moving somewhat fast will find alot of highs and lows.. The hard part is knowing how to interpret what you feel.

I like doing some of my more agressive shaping with a sureform file, or "cheese grater"..the less time you spend shaping a big job the less chance you will sand off stuff you want to keep.

Yes to making the bondo more spreadable, most all of the BPO catalyzed fillers are compatable with each other.

I would not use regular polyester laminating resin though, as we did 20 years ago. (it is not double promoted, and really doesn't catalyze properly with just BPO.)As Brian said, there are much better additives. I use the evercoat 400 as a spot putty and bondo thinner myself.

Use the biggest block that you can fit on the panel. I have a 3' x 8" wide board for big stuff. I use paper from a belt sander for paper, it lasts FOREVER!. :thumbup:

I know that Brian has said some of this, and some of what works for me is not the way others do it.

I don't dance either. :D

later, mikey

Bee4Me 08-07-2007 08:55 PM

I think your whimping out on the amount your applying and working yourself to death.
Load it on and knock it down.
So many think "I just need to fill this low spot but don't realize that low spot is MUCH larger and end up sanding,apply,sanding,apply,etc.
That and being chincy on the cost of the product.
"Man this stuff costs,so I'll only use what I need."
That thinking will work you to death as well.
Forget the cost and slap it on. YOu'll sand most of it off once instead of the same amount MANY times. Make the dust once or 10.
I personally try to metal finish as much as my ability will allow and this goes a long way without using much filler. I just did a lot of patch work which shrunk of course due to welding and because there was no getting to the backside,I used a stud gun and worked the patchs back up. 1 pass with Rage and a skim of Metal Glaze and I'm done. Course,I hammered the Rage on so I'll have enough to level it out cause,
1. I was not concerned with the "cost"
2. I wanter enough to NOT have to go back over it.

crashtech 08-07-2007 09:18 PM

Filling and sanding can definitely be a lot of work. I remember when I was learning I did a lot of stuff by hand, but finally after about 5 years in the trenches, got to the point where I could let the machinery (mud hog, air file, DA) do the bulk of the work for me.

All the advice given here has been good, but maybe if you were more specific about the parts that give you trouble, we might be able to give you more specific advice instead of the ol' shotgun approach.

baddbob 08-07-2007 10:03 PM

When you run into a problem area shoot a picture and post it-and I'm sure you'll get detailed advice on a step by step on how to go about the repair. Knowing how to move the block/board is another often unknown procedure that differs from one shape to the next but there's some general rules I follow. When working over a complete panel (not just a few repair areas) I usually run the block first with the length of the panel-this quickly establishes the straightness of the panel when viewed down the length of the car, if your strokes show that all is good and your getting a good flowing cut from one end to the other (sometimes down the whole length of the car) then switch to an x pattern moving the block/board diagonally at a 30-45 degree angle. After all the major surfaces are blocked straight then do the minor areas like body lines and radius areas using the same technique but on a smaller scale and blending the shapes into the rest of the panel-if this makes sense. There is an order to do this stuff to make things easier and have better results. Guidecoat is a must and should be applied with every grit change. Make sure your blocks and boards are perfectly straight and flat-most plastic and rubber blocks will shrink with age and cup or warp, wood handled boards will swell and shrink with moisture causing warpage, and many aren't straight and flat when new-they all need to be checked and corrected if you want good results.

techron 08-07-2007 10:10 PM

i have 2 tips i learned from an old pro body guy when i was a pup( early 20s) that solved most of my bodywork problems. i was chasing waves in a body panel with bondo and a 14" sanding board and he says " whata ya doin kid" i told him i was trying to get the panel flat. he walked around the car and told me all the panels were wavey, i asked how he could tell. tip1 you dont see bad panels you feel them. as mikey said lay your hand flat on the panel and move it across the panel in different directions. its easy to "read" the panel. he then mixed up a LOT of bondo and and with a big squegee made one swipe across the panel covering covering all my work. tip 2 you dont work a low spot, wave, crease or anything else, you work the whole panel. when it was cured he chucked a new paper in my sanding board and told me to sand the entire panel in 30 degree up and down strokes. in probably 30 minutes i had a flat panel!! i learned you dont get a panel straight by finesseing into shape, you get it straight with a brutal attack on the entire panel. he said if you are doing it right most of the bondo will end up on the floor. its worked for me ever since.

TT66' 08-08-2007 04:24 AM

I should have jumped in about 1-1/2 ago with what Arrowhead has submitted here when I was trying to get the door panel flat on my Firebird. I ended up doing a huge skim coat after not having much luck sanding just around the affected area of damage. I need to get the "read the panel" part down myself. Good thread. :thumbup:

cboy 08-08-2007 07:35 AM


Originally Posted by Arrowhead
... but for some reason, bodywork and bondo escape me.... So I just get frustrated.

Just to let you know, you're not alone Arrowhead. I think of all the tasks related to building a hot rod, getting a straight body panel is the most daunting challenge out there. It seems to be a combination of talent, skill and patience that I've just never been able to master. My theory is it's the Rod God's way of keeping us humble.

35WINDOW 08-08-2007 08:58 AM


Body work is indeed at dark art, something that is mythical and impossible for most mortal men.........well, at least me! :spank:

I have used Martin Sr.'s techniques, along with a lot of you guys ideas, and, while my Car's not done (by a long shot), I FEEL like I'm getting better at it. I believe I own at least some of the Norton Company as I have bought sooooo many rolls of Sandpaper!

Bob C 08-08-2007 10:51 AM

I've found that when a beginer is having a hard time, it's because he hasn't learned to tell the high spots from the lows. If it feels wavy, he will just keep adding more bondo. Look at the whole panel, not just the bondo. Keep practicing and one day you will say holy s--t, I did it.

All times are GMT -6. The time now is 02:07 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.