I overheated by trunk lid during blasting and now it is warped. The lid has a liner with large openings where you can see through to the bottom of the skin. There was an undercoating type material on the bottom of the skin and it was starting to flake off. I chipped and scrapped most of it off before I started blasting. I blasted the skin first and checked the lid, all was smooth. I then flipped it over and blasted the liner. Finally I blasted the bottom of the skin through the openings in the liner. I guess I spent too much time because when I flipped it back over, I had a large sunk in spot above each of the liner openings.

The bad news is that these lids are hard to find in good condition. I waited 2 years before this one became available. The good new is that I have another lid that is in good shape where this one is warped. The vertical rear section of the non warped lid is rotted out. So I can cut the vertical section out of the warped lid and weld it in the rusted lid.

But before I do this, I figure I should take a shot at fixing the warped lid. At this point, I don't think I can hurt anything. The problem is that I don't have any experience with shrinking metal. I have a torch and a shrinking tip that came with the stud gun, I just don't know where to start. Do I need to do any dinging off the dolly work first? I am guessing I should heat the metal from the top around the perimeter of the sunk in area. Should I use the torch or the shrinking tip in the stud gun? I have read some reference manuals and done some internet research but I can't find any advice on repairing large oil canning areas like I have. Any advice would be much appreciated.

I would recommend the stud gun and compressed air for a beginner.
With the heat tip installed start in the center of your oil canned metal. Heat a spot and then cool with compressed air.
Work in a circle around the first spot and continue the process until the metal is firm.

Unless you are skilled with welding thin metal patches you're better off working the warped hood.

The Problem is the Metals surface were you Blasted is Gathered up shrinking the surface.
Think of each Grain of Blasting Material as a strike from a Pick hammer basically.
only you have thousands of tinny light strikes.

gonna be hard to fix you wanna use Hammer on Dolley Plannishing from back side.
Even then without removing the skin gonna be hard to fix.

I have gotten pretty good at welding in patch panels during the course of this restoration. So the welding is probably the easiest thing I am dealing with here. I have welded in enough sheet metal patches to build several modern car bodies.

Doright, I just want to be sure I understand you. You are saying I shrunk the metal on the back side. So to repair, I need to stretch the metal by doing hammer on dolly. I assume I start around the outside edge and work my way to the center of the damaged area.

Doright wrote:The Problem is the Metals surface were you Blasted is Gathered up shrinking the surface.
Think of each Grain of Blasting Material as a strike from a Pick hammer basically.
only you have thousands of tinny light strikes.

gonna be hard to fix you wanna use Hammer on Dolley Plannishing from back side.
Even then without removing the skin gonna be hard to fix.

Dennis,
This being true then he wouldn't really have oil-canning correct?

'68 Coronet R/T wrote:

Doright wrote:The Problem is the Metals surface were you Blasted is Gathered up shrinking the surface.
Think of each Grain of Blasting Material as a strike from a Pick hammer basically.
only you have thousands of tinny light strikes.

gonna be hard to fix you wanna use Hammer on Dolley Plannishing from back side.
Even then without removing the skin gonna be hard to fix.

Dennis,
This being true then he wouldn't really have oil-canning correct?

Not necessarily no, He shrunk the Skin in multiple areas over a skin yes but its attached to a frame or inner structure, Its pulling the Skin down against the frame more than likely. may not see an Oil can issue.
Its really hard to say what the best way to approach any attempt of a repair without seeing it truthfully.
Cutting and welding patches would be the LAST thing I would try to do in an attempt to save panel though.
Way to easy to Planish, what looks totally destroyed by him may be an easy fix to me and then again his minor may be my Disaster I don't know I haven't seen any pictures yet.

I definitely wouldn't get excited and just start beating on it or cutting and welding.
You can do do a lot with just a Hammer and Dolly good & bad this thread needs pictures if the OP has some patients and doesn't doesn't mind the extra work

Here are some photos:

I sprayed some black primer and sanded with a block so the sunk in area would be easier to see.

One of the craters shows up pretty good in this one.

Here is a view of the inner liner. The skin does not touch the liner in any location.

Here is a view of the other trunk lid with the rusted part cut out.

Here is a view of the good section of the warped lid that I was planning to weld into the other panel.

I tried a little repair work tonight on one of the spots. A little hammer and dolley work brought the sunken area back up to the proper level. I think I went to far with the hammer work because I ended up with some high areas. So then I started to do a little shrinking with the shrinking tip in the stud gun. I now have the area where it has the proper contour. If I push down on it it will still pop down like it was prior to repair, but as soon as I release the pressure it pops back up where it should be. So, what do I need to now.

i would hammer and dolly it, it has shrunk in those areas with the ring around it, it needs stretching, basicall wat has happened, the areas that have shrunk has pulled matel from other parts of the panel putting stress on them and that is where the oil canning has come from, i would maybe pull the skin off the frame, panel beat it all out and if you dont have 1 already use a shrinking disc to get all the high spots down, if you dont have 1, get on ebay or google wray schlene and buy 1 direct and for a few extra $$ get the dvd, he will teach you to metal finish, its a great investment, but beware, its truly addictive!!!!!!
krem

You can make it look a lot better but it will never be the same
Use heal dolley pushing up from under and use large Low crown hammer or Flat slapper made from a Old Leaf spring and definitely get a shrinking disk and the video FIRST save ya a lot of learning the hard way.

Your Doing a Studebaker Hawk? what year?
Cool old cars yes parts are hard to find

Dont hit HARD just repeatedly dont need to hit hard just over and over and over close together repeatedly all the while pushing up with Heal dolley and no need to push up hard eith just firm pressure.

Nice looking GT Hawk you got there. Mine is a 61, the last year with fins. Some parts are easy to find but a good ribbed trunk lid is pretty rare. I looked for 2 years before I found this one.

I am trying to understand what happened to the metal during blasting. I get the concept that the blast media is similar to striking the panel with a pick hammer. If I lay a piece of sheet metal on an anvil and strike it with a pick multiple times it will start to curve back in the direction hammer blows came from.

Are the pick marks actually shrinking one side of the metal? The reason I ask is that I can lay that same piece of metal on an anvil and strike it with a flat face hammer and it will still bow back in the direction the hammer blows came from. It doesn't bow as much for a given numbers of impacts, but it still bows. With the flat face hammer it seems that I would be stretching the metal not shrinking it.

So the ultimate question is, does the blast media really cause shrinking on one side of the metal or is it just deforming the metal causing it to bow?