'55 Chevy trunk lid

O

old soul

Member
All went well with the lid (media blast, epoxy, bodywork, multiple blockings, more epoxy) and it is ready for the final prime. Have it in the sun a couple days to cure and notice a faint ripple, about 5 inches long, in the approximate center of the top surface while it is outside. Pull it inside and after it cools down the ripple disappears. It does not 'oil can' at the spot and it does not have any adhesive under it and the inner support. Any ideas on why and what can be done about it? Thanks
 
Could the metal be thinner there causing the thicker surrounding metal to cause this due to different expansion rates. Meaning the thinner metal moves easier when the heat is on it? I would be puzzled as well. Just a thought. I am sure someone will provide an answer and then I will learn something new too
 
Stuff like that is every restorer's nightmare. I don't have any suggestions other than to remove all the coatings in that area and start over with careful documentation just to be sure. Filler there should be nonexistent or very very thin. If it still does it, there really isn't a dang thing to be done for it.
 
Yeah it is quite disappointing to spend so much time and effort to perfect a panel only to have it turn out with a defect which, right now, I am at a loss to how to proceed. I have checked it under fluorescent lamps in the shop and it appears ready to paint (after final prime), no waves or ripples and the reflections flow without any interruptions. One of my concerns is if it moves in the November sun, what will it look like in the July heat. Thanks for the replies.
 
The padding between the inner frame and the outer sheetmetal was removed (it was nasty) and the entire trunk lid was media blasted to bare metal. I had thought that maybe it got some warp at the blasters but there was none that I could see or feel at the time. That is the first thing I check with blasted parts and another reason I like to use black epoxy as the first coating as it seems to show distortions better (easier to see). Not saying it could not have some warp in it but it sure did block out nice (AFS 36" block).
 
does the ripple location correspond to the shape of the inner panel and the open areas where the padding was removed? Is there much build in this area? All temperature induced but it's usually a result of different rates and amounts of expansion and contraction especially if there's large differences in material thicknesses or I should say an abrupt change in thicknesses on a weak or stressed panel.
 
You can try this.....Heat it up good and cool it with ice cold water a few times and see if it changes and/or takes a set. Sometimes things like this will stabilize over a long length of time (numerous heat cycles) if you shock it with a good heat up and quick cool down it can sometimes speed up the process. Then block it, heat it and check, cool it and check. There's no way to confirm how bad the distortion is without seeing it but I know the grief a little ripple can cause when a person is striving for perfection, drives ya nuts! Or strip that area down and try to decipher the cause and what action to take next.
 
Bob, the ripple location is across a part of the inner panel but does not correspond to the shape of it. Half of the ripple is in an open area and the other half is in a closed section, sorta' like the edge of the inner panel and the ripple direction forming an "X" (hope that makes sense). I checked material thickness with an old Spot Rot gauge and it pulled strong all around where the ripple appears, so I assume very little build in that area. It did indicate some filler material about 6 inches to one side but it also had a good pull as if it was slight build.

I will try the heat/cool cycles. It is forecast to rain tomorrow and be in the 50's for a while so good sun is not available soon. Can I use an Infratech medium wave heat lamp? It can easily get a panel hot quickly, as you well know, but it will not be an even heat across the whole trunk lid. Thanks for the tip!!

It looks so good while in the shop and most likely my customer would never see the ripple outside (when it heats up) as it will be white and he is not extremely picky. It will be mentally and financially painful to strip it down but I will if I have to. Thanks for your reply.
 
Could the media blaster have stayed on that area too long with the abrasive? I have heard of car panels being warped if not done right. I read article that stated the abrasive is like a thousand tiny hammers hitting the panel. They said that is where warping comes from not from any heat created. Just a thought. I asked a friend, who has done lots of tri-fives, about your problem. He said he never experienced any thing like it and was puzzled as to the cause. I hope that it isn't too bad of a fix. I also hate having to redo something.
 
old soul;n78540 said:
Bob, the ripple location is across a part of the inner panel but does not correspond to the shape of it. Half of the ripple is in an open area and the other half is in a closed section, sorta' like the edge of the inner panel and the ripple direction forming an "X" (hope that makes sense). I checked material thickness with an old Spot Rot gauge and it pulled strong all around where the ripple appears, so I assume very little build in that area. It did indicate some filler material about 6 inches to one side but it also had a good pull as if it was slight build.

I will try the heat/cool cycles. It is forecast to rain tomorrow and be in the 50's for a while so good sun is not available soon. Can I use an Infratech medium wave heat lamp? It can easily get a panel hot quickly, as you well know, but it will not be an even heat across the whole trunk lid. Thanks for the tip!!

It looks so good while in the shop and most likely my customer would never see the ripple outside (when it heats up) as it will be white and he is not extremely picky. It will be mentally and financially painful to strip it down but I will if I have to. Thanks for your reply.
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Yes, you can use the heat lamp-let it soak up some heat for a half hour
 
…. just my 2 cents …. Leave it alone. Then go talk to your customer first. Show and Tell him of your consultations with other noted specialist. Explain it is not something you knowingly did and is an apparent anomaly. To go ahead or redo will be your customers decision alone as to get back into it will be R & D at this point. Yes white paint will no doubt change the overall effect and time may cure it as well. That is what I would do as a professional and as a businessman. High heat will hardened in the metal in epicenter of the applied intense heat and at the same time stretch the immediate surrounding metal where it was applied upon abruptly cooling back down with the wet rag method.
 
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