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| Cure for rust https://ozdat.com.au/forum/viewtopic.php?t=32155 |
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| Author: | beetle205 [ Mon Dec 16, 2013 10:30 am ] |
| Post subject: | Cure for rust |
Hi guys I'm considering restoring a 1600. Would be spending a few years on it and doing it properly. I'm looking at a shell that has been sandblasted and seems pretty reasonable underneath. My question is, in ten years time after it's all been repaired and painted properly does the rust come back? or is it something you constantly have to work at? I owned one in 2002 that another guy had built and it was mint when i sold it. Saw it on ebay this year and it was rusty as, what have you guys found with your own cars? |
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| Author: | Nissanman [ Mon Dec 16, 2013 11:20 am ] |
| Post subject: | Re: Cure for rust |
Having just restored my Fairlady, my advice is this. Get the bare shell primed as soon as possible to protect the metal. Any rotten areas can then be cut out and replaced with patch panels. Re-prime any repairs. I don't know your skill level, but it is imperative to prime everything with the correct product so that further prep and painting is compatible. The Fairlady was put through a process called Minus Paint which removes EVERYTHING from the metal. As soon as my painter got the shell back to the shop, he primed every nook and cranny to protect the metal from flash rust. If you are going to do the paint job yourself, I highly recommend hiring a booth and seek the advice of reputable painter so that the products you use are all compatible. When it's all done you dose up all the cavities with cavity wax and/or deodorised fish oil and barring a dip in the briney [sea water], the rust won't return. |
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| Author: | beetle205 [ Mon Dec 16, 2013 10:49 pm ] |
| Post subject: | Re: Cure for rust |
Cheers, its been sprayed with a primer since being blasted but not repaired yet so should be ok for now |
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| Author: | d [ Tue Dec 17, 2013 12:08 am ] |
| Post subject: | Re: Cure for rust |
Also some time ago I remember an old car had the oil breather plumbed into the chassis rails lets just say the rails are still perfect. I believe engine oil works probably better than fish oil if you can somehow get it into the problem areas. The best paint Ive seen for priming then straight top paint on compatible primer is POR15 blackcoate or whitecoate, its the strongest paint ever. |
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| Author: | jackjack [ Tue Dec 17, 2013 1:42 am ] |
| Post subject: | Re: Cure for rust |
primer absorbs water so i would be carefull not to leave in it primer for too long, 2 months max, or you will findyourself with alot more work, i got mine blasted and didnt seal it for a while, rust started in all the seems, did my best to sand it and then sealed it but not ideal, you should seal the panel joins asap |
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| Author: | Nissanman [ Tue Dec 17, 2013 9:53 am ] |
| Post subject: | Re: Cure for rust |
You should use the seam sealer after the shell has been primed. The primer needs to be inside all those seams, joins and such before the seam sealer is applied. One of the failings with a lot of cars is the factory seam seals first then primes which is a recipe for rust later on. |
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| Author: | Hatchman [ Tue Dec 17, 2013 10:39 am ] |
| Post subject: | Re: Cure for rust |
Not being a panel beater or body restorer so I can comment there but in my own experience I have found that unless you're prepared to pay big money, and spend the time to learn about what the restorer is going to do, and keep the car garaged, don't drive it on rainy days etc... then these old cars are going to rust. There is something I saw once in a classic car mag, some European treatment where the entire shell is stripped, acid bathed and then submerged in some other kind of primer/treatment that literally coats the metal in every single gap. That would probably be the best guarantee I would think but man you will pay for it. For a 1973 Porsche RS 2.7 yeah you would probably do it, for a Datsun 1600? Man you'd sure have to love that little Datto! |
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| Author: | beetle205 [ Tue Dec 17, 2013 3:13 pm ] |
| Post subject: | Re: Cure for rust |
I was looking at finishing with POR15 for the underbody and gm spatter paint for engine bay and trunk. From what i've read soda blasting seems to be the best option where chemical bath stripping the chassis removes sealers from places which are pretty well impossible to replace properly i.e inside rails and seams. I'm only a mechanic but it makes sense to me to blast the body, clean and prime immediately, carry out all your rust repairs and seam welding then seal again. I guess the reason most of these cars are rusty in the first place is they haven't been looked after like anything special, sand and water in the boot and carpet, poor maintenance, living near the beach, they are 40 years old to. Just wondering if anyone has seen any restos that are standing the test of time? Would hate to put all this work in when it's just going to rust again |
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| Author: | jackjack [ Wed Dec 18, 2013 12:36 am ] |
| Post subject: | Re: Cure for rust |
yeah, well i didnt meantion that seeing as it has already been primed, i used a stone guard i can't remember the name but ill find out for you, you buy a gun thats about $30 to spray it and comes up great, i 2k'd over mine just to make it look a little special but its fine straight over primer and sealer |
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| Author: | RAT510 [ Wed Dec 18, 2013 12:39 pm ] |
| Post subject: | Re: Cure for rust |
from what i have picked up talking to different people in the trade after blasting the best thing is an epoxy etch primer. epoxy paint doesnt tend to be as porous as acrylic or single pack primers. something with a high zinc level is good. after this do your repairs and seal again with epoxy etch. the secret is to have the metal dry and completely seal from moisture from the second they finish blasting it. was also told to sand down after blasted with 180 all over prior to etch. if you doing por15 im guessing it would need to go on the bare metal? from there you can do your metal work welding etc and re seal with the epoxy after each reapir. seam sealers etc would go over the epoxy. avoid applying any filler direct to metal apply over the epoxy etch only. once its looking pretty straight then seal it all up again with the epoxy etch. from there you can primer and high fill being carefull not to break through to metal then top coat another important thing is to pick a product and stick with it and its guidelines. but thats sometimes easier said than done. the question i still have is if you dont want to use 2k top coat can you use acrylic paint over the epoxy etch? what if you dont use epoxy etch. whats the acrylic alternative? some say epoxy etch is porous and some say it isnt? |
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| Author: | Shifty [ Mon Dec 30, 2013 9:45 am ] |
| Post subject: | Re: Cure for rust |
Just a basic primer, will not seal the surface. It's OK for temporary protection but the topcoat is what actually seals it. I've seen plenty of parts that are "primed" but have extensive surface rust on them, in fact the front apron/valance panel that came with my 1600 is exactly that. For any length of time (ie. most restorations), my understanding (limited) is as per the above post - you should use a 2k or high zinc primer. You really need to consult an expert on the coatings you are using. Remember that bodywork and paintwork are expensive for TWO reasons. Labour, and expertise. All that said, I don't care how good your body restoration is, there's no way you can outright guarantee that rust won't come back in ten years. A few years, probably. Ten years? Should be right, but I wouldn't be surprised if you saw a mark or two coming out. Maybe not from your repairs, but from areas you didn't repair that you didn't know were rusty (eg. spot welds, overlaid joints, sections that looked fine but are internally inaccessible without cutting them open "just to see"). |
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| Author: | SR20Datsun [ Mon Dec 30, 2013 2:01 pm ] |
| Post subject: | Re: Cure for rust |
Rust needs a few things to form. One of them is moisture/humidity. If you stop the moisture from getting into the panel/spot weld etc., then the chances the rust will keep going is going to be minimised if not completely eradicated. The reason a Datsun 1600 gets rust in the sills it for example is due to the sills not having paint on the inside, and water can get up in there and start the process. You notice the roof doesn't usually get rust on the top surface. The paint usually protects these areas if it is covered on both sides. Seam sealer should be used OVER primer. Most seam sealers stick really well to metal, but stick better to paint. The other thing to be concerned of is if the sealer is caustic when curing, as this can cause rust too. Good prep work, cutting out all rust and sealing the sections you can't with fish oil/POR products or a good quality zinc prime and paint will mean your Datto will last another 30 years... |
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