The Stovebolt Site Forums The Shop Area Paint and Body Shop Disappointing results, what to do...

Hello!

I've been doing some body work on the cab and bed of my '59 Apache...bought it with the bed off, so it go new inner and outer cab corners, a few minor patches (butt jointed, mig welded, ground smooth), and some minor metal bumping work to remove a few minor dents. I'm pretty happy with the results of the bumping and welding, but I found it necessary to finish most of the spots of with a small amount of bondo...1/8" at the deepest points.

Here's the problem...I put HOURS into sanding the bondo. First knocked it down with an inline sander using 40 grit, moved onto 80 grit on a hand held orbital sander, then to 120 with the same sander. Covered everything with a skim coat of spot filler, hit it with 120, then 220. It was very smooth to the touch, and, I thought ready for spot painting, so that's what I did. I'm NOT ready to paint the whole truck, so I'm using a high quality spray can paint from an autobody supply store. I just want to cover the work so that the elements won't affect it.

After the paint, I can see the work from 3 ft away EASY. My reflection is perfect on the orginal metal, but when I move to the repaired part, it's pretty obvious because there are subtle waves in it.

How do I get rid of the waves and make the surface as perfect as the original metal surface? They're pretty subtle, but they're there, and it bothers me, especially after putting so much work into smoothing. Block sand? Or?

Also, when I was finish sanding, I wore through the spot putty in a few places, and you can see changes in the texture through the paint. How can I avoid that difference?

I'm very new to body work, so the answer might be obvious for some, but I'm learning as I go.

Thanks...

Chris

Chris,
First a disclaimer. I am no expert but since you are new to body work also perhaps my experience will help you. I took a semester course at a nearby community college in autobody and I would guess the mistake you made was using power sanders on the bondo (filler). I know others with more experience will chime in but I believe you should use block sanding by hand, approaching the area at different angles. I think that allows the block to use the surrounding normal metal to act as a guide, as you sand.

For the course, I worked on my COE fenders, which had a few significant dents as well as marks from a chain that had penetrated the fender ( I think they were trying to pull the truck with a chain around the front axle and the chain broke). After much hammer and dolly work, combined with welding the perforation closed followed by heat shrinkage, I used a thin skim of filler and block sanded. You absoluteley cannot see any of my repairs after it was painted, so I know if you block sand it, you will be pleased, as well. If I can do it, so can you! Now painting, that is a different story.

Regarding the change in texture where you wore through the putty, I would think if you primed and sanded the primer properly, you wouldn't see that. Perhaps you needed to use a high build primer.

Kent

Chris - you need to do some initial sanding of the filled area, then "guide coat" with sanding primer and sand that nearly off - doing that repeatedly will let you see those waves and gradually reduce them to something acceptable as a starting point for the paint job .... also primer is a must before any paint, even temporary, and a thick sanding primer is better than spot putty

Bill

Hi Chris,
Bondo work takes a lot of practice and patience. Patience is the key. It's hard to say what went wrong without seeing it, but you probably need to spend a little more time block sanding. maybe one more wipe of putty and a final blocking.

If I have to do a lot of plastic work, I like to use a high build primer, and then block sand the primer with 400 grit. Sometimes I use 320 then finish with 400 if I have a lot of blocking to do.

One thing to keep in mind, when you run your hand over your work, if there is anything that you can feel, youre gonna see it when it's painted.
That always tells me I need to spend some more time on it.

If you are new to body work, the best way to learn is by hand, using hand board files and hand blocks.
It all comes with practice and experience.

Barsteel

Appreciate the humble attitude. I too have been teaching myself autobody paint.. for about the last 4 years and it takes a lot of practice to get street rod hand rubbed results. (my work now looks better than 2010 factory base coat/clear.

I assume you are doing just a single stage? Basically the results are locked in with sanding. Block sanding is must, but after dry sanding I switch to block wet/dry sand at 600, apply filler prime, block wet sand 1000 and then final prime and knock it down with a light 1200 prior to final paint. Over filled areas multiple top coats is a must. If it is single stage I will then rub out the final paint with 2000-2500 and use a buffer with a 3M perfecta compound to bring it back. I still do the same on a clear coat, but many are satisfied with the factory finish.

good luck, it takes lots of practice

To all -

Thanks for the comments. Based on what everyone's telling me, I didn't property sand the bondo enough. I did NOT block sand it, which is probably why I have the waves.

Assuming I sand off the paint, what would be my next move, sand with a rigid block with, say, 220 grit or ?. Also, do I sand from multiple angles, i.e. side to side, then straight across the repair, then diagonally? What should be the final grit before I lay high-build primer? Also, should I just forget about the spot putty?

This area is on the lower side of the bed in front of the driver's side wheel well. The damage was a long crease caused by someone probably scraping against a rock, so it'a a fairly long repair, about 18".

At this point, I have to get the bed floor installed, mount the bed, then get the truck registered before I seriously dive into the body, but I do want to put some more effort into getting these spots to the point where you cannot see them.

Thanks...

Chris

Chris, get a long board file and sand it by hand with 80. Get the paint off and try to flatten out the waves. Dont bear down, but let the weight of the long board do the work.
Go over it till you feel confident that it's flat. Then what I like to use is Evercoat Metal Glaze Part#100416.
Wipe a coat of that over it, then sand it with the long board with 80, then finish it with 180.
You can go over that again with 220 if you want, it will help get out any extra sand scratches.
Again, dont bear down when sanding, but let the weight of the sander do the work.
Good luck!

I think there have been a lot of good advice, but some that will get You into trouble very quickly...1. spray Your high build primer on, 3 coats, then after the primer flashes, spray on a very light coat of any color just so it contrasts the primer color, then when dry, if You don't have a inline sander, then use a board sander using 80 grit paper start sanding the work area, the first thing to go will be the guide coat, it will show you the high spots as well as the low spots...It will also show You if maybe might have to tap the high spots down, then re-coat, if necessary.
Next, use 220 or 240 grit to re-block...I had a body shop for 30 years, and taught metal finishing, and did show car painting for cars that were in the auto shows. A total of 55 years experience...good luck.

Sounds like you didn't use a block while block sanding. Get yourself one of those Dura block sanding kits and use them for all sanding. It's the only way to make sure everything is straight. I always sand from different angles, just make sure the block is long enough to contact straight metal outside of the dent area as that is what guides the block. Then use a 2k primer (or whatever is recommended on the filler) over the filler and sand that again with a guide coat.

It takes a lot of time and patience. I've had to re-sand spots 4 or 5 times before it was perfect.

Good luck.

If you can feel it, you will see it.

These guys no doubt know their stuff, but I wouldnt be sanding a final coat of prime with anything so aggressive as 220 grit, take your time for the prep and go for a smoother final finish