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Jan 18, 2023 15:10:53 GMT
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So the car i bought is rusty, seems the previous owner got it dipped, but didn't get it e-coated so its in the seams and floorpan - mostly solid except where the acid appears to have collected in the cage boxes and rotted each corner out. So i don't think i have any other choice than to get it redone, tough properly this time with the e-coating.
I'm thinking I'll drill some holes after welding in some areas that can pool acid, then put a grommet in before final paint.
but if anyone ha any advice or experience or things they wish they did before or after the process i'll be glad to hear it. Thanks
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stealthstylz
Club Retro Rides Member
Posts: 14,925
Club RR Member Number: 174
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Jan 18, 2023 15:41:08 GMT
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Bit late now but my advice is avoid the whole process like the plague. Unless you split every welded seam on the bodyshell after dipping and clean it out they always rot out the seams. Had several show winning/mag feature cars come through work that 12-18months post debut were rotting like a Mk4 Escort in a seaside town.
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Jan 18, 2023 16:12:22 GMT
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Media blast them every time, then phosphoric wash before picking the parts/shell up.
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Jan 18, 2023 16:55:03 GMT
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I knew i'd get that answer, but I can't physically get at the rust now its done.
Besides, modern cars are dipped the same way, the difference is they are designed for dipping with the appropriate drainage, something I would need to add and something I think classic restorers overlook. The previous owner overlooked this also by enclosing the cage boxes.
But if anyone has any tips on a successful process or problems they encountered that I haven't thought about, then I'd be glad to hear it. Or tips?
But it has to be redipped because it was before.
Will also rust inhibited project binky style.
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As it's already been dipped I can't see you have much to lose by having it done again.
E-coating doesn't work well in closed sections or close fitting panels which is why most modern manufacturers also use zinc coated steels in vulnerable areas.
More of an issue than drainage is making sure air pockets don't occcur, ideally they would rotate or at least tilt the shell to minimise this, same afterwards when it's draining.
Once it's done, you would ideally bake it to get it really dry then seal the seams you can get to and after paint give the back surfaces of them a really good coat of a penetrating anti rust wax this is about all you can do.
It's also worth mentioning that for the last 20-30 odd years manufacturers have been using adhesives in the seams as well as spot welds to add both strength and stiffness, these should never be dipped as the adhesive is also disolved away.
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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If it's been done properly ie. in a phosphoric acid dip then its not going to be the acid that has rotted anything. The chemistry simply doesn't work that way. The chemicals can leach out of seams and damage paintwork which can lead to normal rusting again but it's not as common as people make out if the proper process is followed.
It may have been dipped in a hydrochloric dip insted which will remove rust but as mentioned will eventually rot out the seams as you will never be able to fully neutralize the acid.
My advice would be to send it to a reputable outfit to get it done. There's only two in the UK. Each uses a different stripping process but the acid dip will be the same. As you mention tho it is imperative you drill holes to open up paths for air and fluids to escape of you want it to work properly. Old cars weren't designed to go through an e-coat tank like modern stuff is so the shells arnt designed with the nessicary venting.
Dipping gets a bad reputation because people don't really have a clue about the different processes used. When done properly it has its place. Same thing can be said about blasting really. Loads of pitfalls there too if done incorrectly. Suggesting you should avoid acid dipping to blast and then spray the very acid you would have dipped the car in in the first place is just darn illogical tho!!
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v8ian
Posted a lot
Posts: 3,824
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Jan 20, 2023 11:00:15 GMT
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I cant think who does this system, but they heat the shell up to a good temp to burn off the paint, seam sealer etc, As a time served engineer this just seems plain WRONG, The process looks like it blues the steel, thats about 600degs chaps and may well exceed this temp looking at the grey steel I have seen, any tensile steel used in the construction has probably lost is temper, and would be in the area of "NEVER BUY A FIRE DAMAGED CAR" not only that, some of the chemicals released during burning are exceptional toxic, and some may even produce acidic residue, I once had a long conversation with my brother in law, a Fireman and safety rep for the brigade, advised be NEVER to go near a burnt car because of the toxins released, including Hydrofluric acid from some of the plastics used in paint.
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Atmo V8 Power . No slicks , No gas + No bits missing . Doing it in style. Austin A35van, very different------- but still doing it in style, going to be a funmoble
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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Jan 20, 2023 12:56:12 GMT
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Yeh I'm never too sure about that process. You will find alot of blasters use a simalr process before blasting a shell tho too so it can apply to both options.
Biggest problem with dipping nowerdays is that they have basically outlawed the use of DCM which in my opinion is the ideal process. One place uses the oven method as you describe and one place uses a caustic stripper. I'm pretty sure it's the caustic that gives the leachy seam/paint issues tho so neither process is perfect.
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Jan 20, 2023 13:05:02 GMT
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I believe the baking is low bake, no-where near the temps you think Ian.
The 'grey' finish you see is the phosphoric etch finish on the car.
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