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Wavy bodywork

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21K views 46 replies 26 participants last post by  tibalda  
#1 ·
I went to a local car show with hundreds of cars and couldn't help but notice how many of them had nice looking professional paint but very wavy bodywork. I realize the effort to avoid that is blocking and re-blocking before paint - but probably 80% of the nice paint jobs had wavy body work. It will be something I focus on when I start my panel repairs but is it almost impossible to get it right? All of that said I still would have loved to take about a half dozen home with me :).

Art
 
#2 ·
Generally, the difference between decent bodywork and great bodywork is a decimal place. If you're doing your own, take your time estimate and multiply it by pi to get an accurate time estimate.
 
#3 ·
The darker the paint, the more important a straight body is. A wavy body panel is easily avoidable by spraying a guide coat before blocking. If there are areas of guide coat left after blocking, they are indicators of a low spot, and will need filling to bring them up to the rest of the panel. After initially spraying 3 coats of high build primer, I usually start my guide coat blocking with 120 grit, and keep repeating until all of the guide coat is completely sanded off. Then, I lay down one or two coats of high build primer, and guide coat again with 220, and repeat that with 320. That's where I stop for the single stage non-metallic paint I use.
 
#7 ·
I forgot to add that important bit about using long boards/blocks for best results. Use the longest board/block that is practical. Always work it in an X pattern.

When I do an initial shaping of the panel where I've spread a skim coat of filler over it, I typically start with 40 grit. Once shaped, I switch to 80 grit. This may sound extremely coarse, but I use it for the reason Rick_L touched on. As you're blocking, you want the sandpaper to cut through the high spots of filler or primer, not ride over them. The coarse grit will cut through them and level the surface out better and faster.
 
#6 · (Edited)
I have seen that on a couple of cars and I swear its these orbatial da sort of palm sanders that seem to be the rage that may be causing the ripples, i.e., a lack of final blocking. I am no body man by any means and my car, which I painted as a teenager and early 20 something in a driveway a couple of decades ago, has many many of those attributes. So I think Rick and the others are more then just a little right. Long boards, careful sanding, guide coats and lots of primering and blocking.
 
#8 ·
I have blocked sanded many cars laser straight. After body filler, I start with a cheese grater where needed. Then, use sanding boards from 7" to 16" long. I Buy boxes of 3M sandpaper 40wt on up, pre-cut for the 16" and 10" boards. Then, use guide coats to see the low spots. Also, I use various diameters of rubber hose (1/2" - 6") wrapped with sandpaper for the curves.
 
#9 ·
Note that if you have the body media blasted, make sure the company you are using knows what they are doing, and discuss how the body panels may warp as too aggressive a media will create heat, and hence warpage of the panel. If they aren't aware of this, look else where.

Mucho, mucho hours of careful and patient block sanding will result in straight panels.
 
#11 ·
A guy once asked the owner of a car with incredibly straight panels, "How do you get them so flat?" His answer: "With hundred dollar bills." Maybe an old anecdote, but still very true. Unless you're one of those incredibly talented craftsmen who is capable of turning out that kind of work, expect to spend a ton of $$$ to have someone do it for you.
 
#12 ·
The doors on my '39 Chevy coupe are extremely long, and very tall top to bottom. And since I had to replace the bottom 5" of both doors, they needed a lot of metalwork, and then days and days of sanding and rechecking to get them acceptable!
I bought the 3 ft. hard durablock foam sanding pads, and 3M self adhesive rolls of sandpaper. But even those long blocks flexed too much, so I ended up buying some 2"x1/2" boards and cut them to length and then screwed them to the back of the durablock sanding pads so they'd be less flexible.
Some satin black spray paint as a guide coat, and God only knows how much filler went on the doors, only to be sanded off on the floor. I've never gotten the proper technique to get it right in one of two tries, so I kept skim coating the doors, and then sanding it off, until somehow it finally passed the guide coat test!
 
#14 ·
My fingers hurt just by reading this thread 🥴
Just when you think your finished hit it with guide coat again to ensure, you’d be surprised what ya miss when you’re burnt out from blocking.
It takes patience and that’s why fluids go in motor last so I’m in no rush to hit the streets.

Happy blocking lots of good advice above ☝, and ibuprofen helps to!
 
#17 ·
I am taking your advice to heart be because pressing too hard and creating waves is something I would do. Also following Blakwidows suggestion I will plan to wait a couple of weeks and re-block everything a few times more. Lots of other good advice so I am going to preserve this thread as a reference guide.

Art
 
#20 ·
I couldn’t help but notice a lot of waves a recent show as well. I don’t think it was as much bad body work as it was a lack of it. A lot of guys strip their cars to bare metal, prime and paint. Many are under the impression that the panels were built straight and smooth from the factory not realizing in reality, their nice paint will be as wavy as the Pacific. Getting these panels straight takes a great deal of time and patience.
 
#22 ·
While I was waiting to go to paint jail, my restorer suggested that I take a go at prepping the car. I placed filler, used sanding blocks, guide coats, X- pattern, then after hours and hours he'd come by and with the palm of his hand he'd go along the panel and say there's a ripple here. I could never feel it. The 55 ended up at a local body shop and he did wonders, but used a small tongue depressor for blocking and its black.
 

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#25 ·
Probably a paint stick instead of a tongue depressor.

I've seen many many shops (employees) do their body work, prime and guide coat it, and then sand. The problem I've seen as they were sanding is that some:
*use too small a block
*use a DA to sand the panels
  • sand in one direction only
  • rough sand the entire panel, then spot pick where the guide coat shows it's low and only sand those areas creating dips.
  • start with light pressure at the beginning of the stroke, gradually heavier pressure in the middle of the stroke and lighter pressure at the end of the stroke. Kind like part of a half moon while sanding. Long even pressure strokes and cross hatching are the key.

It takes a lot of practice, patience and Talent to make a car very straight. If you can do it yourself you can save a lot of $$$$ in prep work. If not the shop may charge a lot of $$$$ to fix it or they may just spray it and walk away leaving you with a less than desirable body effect.


I haven't used Guide coats for a long time, but then again the colored primer line I use does a similar purpose. The unsanded primer will be darker than the sanded primer and you can see the sand scratches and depths of them vary where it may be high or low. I can also see the coarser (180) sand scratches after switching to finer paper (320-400) and will know when the deeper sand scratches are gone and it's ready for paint.

Another helpful tip when you think you're ready is to use a prepping spray (wax and grease remover type that will not leave a residue) and wipe the panel while looking down the side with light at one end. You will definitely be able to tell if the panel is straight. If it's not, Keep at it.
 
#26 ·
I'm not going to say every body-shop is the same but there's a lot of difference between getting a daily driver insurance job done and true custom body work. I think what you're probably seeing at shows (haven't been to one in two years now myself) is that the majority of people take their ride in and are probably already in stoke territory just getting an insurance level paint job done. With the cost of materials, man-hours, government fees and some profit for the business, you're looking at serious dollars for a complete paint job at that level. Then you start talking about blocking out panels piece by piece and you just sent the number sky high. I think a lot of people want paint on their ride, it's normally the final or next to final step in the project but at that point, the project has already consumed a lot more cash than it was ever expected too. So they settle for a job that looks pretty damned good at 30".
 
#30 ·
Paint is just the color over good body prep. The better the prep (talent) the better the paint will look. Spending big money for materials and poor prep is a fools plan. I have made blocks for areas that need
special attention. Knowing how to block is priceless. You can block problems into a panel as well as remove issues just by knowing how to and how not to. Long panels need to be blocked with 18 inch
block. Guide coating is my friend!

Mikey
 
5
#32 ·
I must have pressed too hard. I was really happy with my results and darned proud of myself with the mess I fixed, until I saw two large indentations. It's 'almost' like oil can type areas. From behind I can push them out without too much pressure. I saw someone once with an oil can spot in the quarter panel and he put a fiberglass 'patch' on the backside from the trunk (not a tri five) which fixed it. I'm wondering if something like that can fix mine. I'd really hate to bondo two, about 6x12" area's. I believe a pro could hit it just right to make them stay out. Didn't see them in primer, but with black primer sealer that is satin and will give a reflection, they come to life when eyeballing it down the side. I suppose sanding it and putting heat on them might fix them?
 
U
#33 ·
Just went through body and paint on the 55 210, a good friend hired to do the body work, an old timer that does mostly Tri-5s explained how some of waviness you see in finished side panels comes as a result of over tightening the clamping brackets inside those long side trim strips to the point of visually distorting the panels. A good tip worth considering when putting things back together.
 
#36 ·
We use a 18" flex block. It has stiffener wires in it. You can alter the flexibility by pulling the wires, or leaving a combo of them in.
Just tried to buy another, and the guy making them has passed.
Guide coat powder here.
 
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