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  #136 (permalink)  
Old 02-18-2008, 02:48 PM
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Some black stuff like that is a tar based sound deadener that was used by some car makers... Yucky stuff.

It can be scraped off with a putty knife. A few people have used Ice to make it hard and easier to remove. IIRC someone used dry-ice and was able to break it up.

USE CAUTION!!! Dry ICE must be used in a well vented area. It will displace the air - oxygen you need to breath.!!!!!!!

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  #137 (permalink)  
Old 11-01-2008, 01:55 PM
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  #138 (permalink)  
Old 11-22-2008, 06:57 PM
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I have a question that has probably been asked, but I did not specifically see it.

What can you do about rust that is deeper into areas that cannot be easily cut out and removed? I am talking about the surface rust that is back inside the nooks and crannies that is basically impossible to get without completely ripping the car apart and I am pretty much doing that. My body is on a rotisserie.What would happen if I turned it up side down and sprayed a acid or acid based product into these areas and then applied a product like a body cavity wax by Wurth?
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  #139 (permalink)  
Old 11-29-2008, 03:20 PM
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Removal of the black

I given the Naval Jelly a try - It seems to be working, but I can not find a way to remove the "Black" that is left over - I have used hot soapy water and even scotch brighted and the black stays put.

What should I be using to remove the black to see if I can get to clean metal

Clark
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Old 11-29-2008, 07:44 PM
 
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What "Black" are you referring to? Is it old paint or from leaving the stuff on there too long? You can always apply more to the surface.

Aaron
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  #141 (permalink)  
Old 11-30-2008, 02:34 AM
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A wire brush in a drill works good.
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  #142 (permalink)  
Old 11-30-2008, 10:28 AM
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Maybe I mis-read this thread - I understood the Black remaining after using the Naval Jelly to be Zink Oxide - After re-reading - I am not sure what the remaining black residue is.

I have a couple of hours of work on this Panel and do not see anything that leads me to believe the Naval Jelly is working. As you can see the panel is very pitted.

So far I started with about a 12" x 12" area I have:
Wired Brused (Via a drill) to remove the high spots of the rust

Hit the area with both a brown and a red scotch bright pad to try to get to the surface

Naval Jellied about 3 times. I used the Jelly with steel wool, let set and reworked the surface each time - Then washed off the surface with warm soapy water

Then I tried the Naval Jelly over night: I applied the naval jelly and covered with plastic.

I then washed off with Warm Soapy water, and again hit it with the Red and brown scotch bright pads.

The whole car is this deep pitted rust - I would like to use the Naval Jelly approach, as I do not want to grind this rust away as the pits are deep. If Naval Jelly will not work - I will probably need to have the car dipped - and that will be expensive.

Please advise

Thanks

Clark
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  #143 (permalink)  
Old 11-30-2008, 11:50 AM
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I believe the black is zinc oxide.
I've had this "protetive" coating when using rust remover.
I hit it with a wire brush in a drill and the black came up revealing rust underneath. I used the rust remover several times until all the pits were free of rust.
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  #144 (permalink)  
Old 05-02-2009, 06:07 PM
 
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Just have to put in my 2 cents worth ... I do have a degree in chemistry for what that is worth.
1) I completley agree with the advice NOT to use Sulfuric acid (battery electrolyte) or Muriatic acid (hydrochloric acid). Neither of these quit eating steel when they dry - they just get stronger. Phosphoric acid (Ospho, Navel jelly is a 'weaker' acid. It will not react with steel, but will react with rust, hence it is self-regulating and will not eat good metal no matter how long it is left on. If holes appear later it is because the metal was rusted through to start with.
2) If you MUST use Hydrochloric or Sulphuric acids, strong base will neutralize it. Sodium Hydroxide or Potassium Hydroxide. Sodium Hydroxide is Lye, and may still be found in grocery or farm supply stores. (But don't use lye-based drain cleaners containing also aluminum). These strong bases will not eat steel ever, but they are DEATH to any aluminum or aluminum containing parts like die-cast. They also leave a 'soapy' feeling residue to which paint will not stick. You would need COPIOUS amounts of water to remove this residue. One of the phosphoric acid products should help neutralize the base and remove it. Baking soda will also EVENTUALLY neutralize the strong acids, but it takes so much it is doubtful you would ever get completely rid of the acid that way.
3) The black stuff left after treatment with one of the phosphoric acid products is iron phosphate. It is neither acid nor base, will not rust further, but provides no inherent rust protection either - it is just converted rust and the conversion process can only go as deep as the acid solution reaches into the rust. Hence the need to remove the heavy rust deposits mechanically.
... It is NOT zinc or any zinc compound. which brings us to ...
4) If there is some product out there that converts rust to a zinc compound I would like to know about it, because zinc is the sovereign remedy for permanent rust prevention. It is the material from which 'anodes' and galvanizing is made. Unlike epoxy, rust conversions, or other similar products zinc actually does PREVENT further rusting by means of a sacrificial chemical reaction. You can scratch through a galvanized coating to the bare steel underneath, and the zinc nearby will, by means of a sacrificial chemical reaction prevent rusting in the scratch. Try that with epoxy or any other paint and the bare metal that is exposed will rust in the scratch and under the paint away from the scratch.
5) I have never done a complete strip job like that described by Randy Fergusun, but his method seems sound. I have on the other hand treated at least 10 old cars with my own undercoating method and some of them have now been on the road for over ten years with no rust-through. (I do not suggest that this is as good as a complete strip and clean job.)
a) remove heavy rust mechanically with any method that works for you, wire brush, sandblast, needle scaler, etc.
b) Ospho applied with one of those air atomizer guns that have a suction tube that you stick in to the container. Make sure you get into all of the nooks and cranies and hidden areas. Take out the plugs or drill holes if necessary. Sometimes I will apply several coats.
c) After the Ospho THOROUGHLY dries (this can take days if you have filled hidden pockets which do not drain)
d) zinc chromate primer applied with the same atomizer gun (clean gun with solvent afterwards) note that zinc chromate is no longer available to the 'general public'. I buy mine from the aircraft supply company. Put on a good thick layer by applying several coats. Fill seams and other cracks. Note that this is flammable material and you are making a fog of it so keep ignition sources away, also the solvent is not very good for you. I work outside whenever possible for this step.
e) when dry, Rustoleum red oxide primer, (which used ot also have zinc chromate in it but doesn't anymore).
f) and finally when this dries, rubberized undercoating.
NOTE that regular car paint will not stick to Rustoleum and while it will stick to zinc chromate, the zinc chromate is not as aggressive a primer in terms of adhesion as epoxy or regular auto primer, so this is primarily an undercoating method. Supposed zinc-rich epoxy isn't worth the money in my opinion. The zinc effect is lost becasue the zinc particles are coated and electrically insulated from the metal by the epoxy.

-- cut and weld to replace rust ??
NOT FOR ME. >>EVERY<< time I have seen this done, rust comes back at the weld, because you have weakened the metal with the heat of welding, even with spot welding. If you MUST do this, scrupulously remove any welding flux or scale and then you can try 'cold galvanizing compound' (check your welding supply store for a source). This is another zinc rich paint.
I much prefer 'body panel adhesive' to welding - a two part body panel 'glue' the sell at the paint and body supply store. It is way strong and some modern cars are actually held together with it. Up to you whether you want to trust it for a structural application.

POR ? I've tried it a few times, and it seems to work better than regular paint but not as good as zinc chromate, but I have never found a way to get car paint to stick to it, so I never use it on something that is going to get painted over with a finish coat. Maybe others know how to get paint to stick to this stuff, but I have never found any primer or other product that works.
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  #145 (permalink)  
Old 05-05-2009, 02:37 AM
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Interesting post kground, maybe you can answer some questions that Iíve had (for some background, I grew up in the ďrust beltĒ were we got really good at fixing rust holesÖ every spring after a long winter, but it never seemed like there was a long term solution, and most of the ďmiraclesĒ that people talked about didnít really work or in some way made things worse):

- Most phosphoric acid based rust removers advertize that they leave a protective phosphate coating on the treated steal, and they do leave sort of a white haze, which seems to prevent rust from starting till it gets wiped off. I would guess that this is some of what the protective value of ďetching primerĒ (primer with phosphoric acid) has. Is there any reason to leave this on and coat with the next step or just clean it off (most products recommend water to clean it off, and I have a hard time seeing how youíre going to do that without causing some flash rust)?
- I draw a pretty clear line between removers (navel jelly, metal prepÖ) and converters (ospho and stuff), where you seem to have a somewhat fuzzy lineÖ part of your answer you donít seem to like the converters that much, but you seem to feel they are an intrinsic part of dealing with rust in ďyour process.Ē What do you really think of them? Some people seem to swear by them, and others swear at them. I generally fall in the second category and have wondered if Iím doing something wrong. When Iíve used converters Iíve taken much the approach that youíve listed here: mechanically removing as much rust as I possibly could before applying. Iíve found that if there is no rust where applied you get a clear, rubbery surface that takes forever to dry and is just plain difficult to deal with. If there is a little rust there for it to react with it converts it to the hard, black iron phosphate which can be just as difficult to deal with for different reasons. I havenít seen problems with automotive primers sticking to it, but the clear, unreacted surface tends to peel off the bare steel. The reacted rust reformer usually has a rough surface, which normally would need some body mud over the top of to smooth/disguise it. Iím not sure which is worse. The unreacted stuff tends to come off and then it doesnít protect the surface, but the reacted stuff makes a hard shell that more often than not Iíve seen rust start forming underneath. Not only is the new rust a problem, but the shell over the top of it makes it more difficult to clean up and deal with the second time around.
- Why zinc chromate over the top of ospho? Ospho supposedly has zinc chromate in it.
- Which rustolium red oxide primer do you use? Iím not sure that the stuff in a spray can is anything more than any other primer pigmented to be that color. The stuff that comes in a can is quite different and works much better, but I havenít experimented with more conventional top coats over it. I would hope that it would work well with most topcoats if they sell it as a primer, but I donít know for sure. I was under the impression that there was a completely different rustolium primer that had zinc dichromate in it (possibly the grey water based stuff?)
- Preventing rust when weldingÖ well the trick is that you need to prevent pockets that hold water. Smooth welds with no cracks or grooves help and are pretty difficult to do on thin gauge steel and still controlling warping. A water tight filler (something Ďglass reinforced) for the first coat also helps
- I havenít looked through PORís product line lately, but they used to have a tie cote product used to allow more conventional top coats stick to their stuff. Otherwise, the trick is to hit it with some primer or the first coat of the top coat before itís _completely_ dry. If you do let it dry completely then sanding the shiny finish off supposedly works, but Iíve heard that itís a lot of work and Iíve never tried it to be sure. I suspect that the color might make a difference also. Iíve only used gloss black and silver POR 15. Iíve never top coated the black, and I suspect that it would be quite difficult. The silver is pretty different than the black, itís much thicker and almost like a filler, you can use it over uneven surfaces and it will smooth things some, and that is the color that Iíve painted over.
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  #146 (permalink)  
Old 05-05-2009, 03:55 AM
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If there is any black iron phosphate ( I think I got it right now) left on your repair, that means your repair is not finished.
Wire wheel the black away and you will expose fresh rust below.
Repeat until your rust remover leaves no black and only then are you finished.
No need for POR15 or any other patch work. Only removal can stop rust.
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  #147 (permalink)  
Old 05-08-2009, 04:43 PM
 
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Correct, the black stuff is 'converted rust' and is not the bare metal you want if you are doing a complete job of rust removal.

That said, note that the black stuff won't rust . . . BUT . . . (and here is where the problem comes up with 'rust converters) if there is any rust under the black iron phosphate then that rust is not protected in any way or prevented from further action. Hence the need to mechanically remove thick rust before converting. THe converter can work no more deeply than it can soak into the rust. How far does water soak into metal ? Not very far. So converters can only be effective for thin layers of rust. thick rust or rust that has got to the point of starting to scale (intergranular corrosion - rust following the grain boundries in the steel) MUST be removed before using converter or the rust will just come back. Once scaling starts it is highly you are going to get rid of all of the rust by any means short of removing significant amounts of metal, since the rust has started working between the metal grains, though you may get some effective protection by excluding oxygen and moisture.

The white hazy coating that forms on clean metal is dried phosphoric acid (very gummy stuff). it probably provides some protection against future flash rust, but it almost certainly is going ot adversely affect the adhesion of any paint product that you might apply over it.

Ospho claims to contain zinc chromate ???
Never heard that one, and I would be surprised, assuming we are talking about the greenish water based Ospho rust converter and not some paint product that may have the Ospho name on it.

Rustoleum: The original brush on Rustoleum red iron primer contained red iron oxide and zinc chromate and was excellent for rust prevention. As far as I know NO consumer or auto paint product for sale in the US including the present brush on or spray on Rustoleum contains zinc chromate, though it may still be the same color. Uncle Sam in his infinite wisdom decided that the tiny amounts of hexavalent chrome and zinc in zinc chromate was a threat to the environment and was not to be trusted in the hands of the likes of you or I. The last time I got zinc chromate was from the aircraft supply house (it is or was at that time still permitted for aircraft painting use, since it also is one of the few things that protect aluminum against corrosion). But it wouldn't surprise me if it is no longer available from that source today.

As far as paint adhesion to Rustoleum - my auto paint supplier explained it this way: Rustoleum also contains fish oil. In fact that is about the last beneficial ingredient it has since they took out the zinc chromate. The fish oil helps by flowing and forming an oily skin that dries and at least in some cases blocks oxygen from the metal or rust. Only problem is that (as explained by the Man) NO auto finish or primer will reliably stick to fish oil. Same way you have to wipe down your car with solvent to remove all traces of oil before spraying to prevent flaws from oily fingerprints and such, the fish oil keeps your topcoat from sticking. Rustoleum topcoats are formulated to deal with this problem somehow and of course they stick well to the Rustoleum primers, but in my limited experience auto paint won't stick to Rustoleum topcoat either. Maybe it also contains fish oil.

Not sure about any paint containing zinc dichromate, except that the dichromate would be somewhat less effective rust prevention. Doubtful the grey stuff has anything except some grey mineral pigment in it, but I am guessing here, not speaking from actual knowledge. I know it doesn't prevent rust very well for any length of time. (either grey Rustoleum primer OR grey auto primer)

Another thing the auto paint man told me: ALL Primers (talking about auto primers here, not those which contain fish oil) are porous and to completely protect the metal underneath they require a topcoat since topcoats are not porous and provide the final barrier to oxygen. Primer a car and let it wait for a few months or maybe less before applying the topcoat, especially if it gets wet or moist, and though it may still look fine, rust has started underneath and your finished paint job will not last. . .

Last edited by kground; 05-08-2009 at 04:50 PM.
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  #148 (permalink)  
Old 05-08-2009, 05:16 PM
 
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"Primer a car and let it wait for a few months or maybe less before applying the topcoat, especially if it gets wet or moist, and though it may still look fine, rust has started underneath and your finished paint job will not last. . ."

Um, far as I know (little), you would/should use epoxy. Then you would have sealed it. I did the phosphoric thing to areas I stripped on mine and it hazes like you say, but a clean rag with lacquer thinner takes that haze away. For grins I sprayed a little paint (ACO spray can) on one area without removing that haze. Paint dried OK but it had to be sanded off, sure wasn't not sticking and no primer either. I would clean everything again just prior to epoxy, maybe use two coats of that and it should be forever from what I understand... provided it's all good. I don't have surface rust, but a few spots rust thru. I figured best to strip it all so I can see any rust that might be hiding. I'm actually enjoying this. In all my years I never thought twice about this stuff, bodywork paint etc. By the time I get any experience I'll be an old timer LOL

Sock it to me...
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  #149 (permalink)  
Old 01-26-2010, 05:23 PM
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Quote:
Originally Posted by Randy Ferguson
The naval jelly will etch the surface, but I've found I get better results by sanding the metal with 80-180 grit prior to applying the epoxy. If you use a high quality epoxy primer, such as this one from Southern Polyurethanes, Inc. you shouldn't need to apply a metal conditioner.

http://www.southernpolyurethanes.com...oxy_gallon.JPG


I've found their products to be second to none!!



Willys36,

The '40 Willys Coupe belongs to a client. The metalwork is scheduled to be completed in May.

I'm using this one to make the necessary bucks, patterns and forms for the '37-'42 Willys replacement panels. I sell a complete line of inner and outer sheetmetal parts for these.

I am also working with a gentleman with a '35 Willys coupe, who is interested in letting me use his car to make all the bucks, patterns and forms from it to start producing the '33-'36 Willys sheetmetal as well.

Also in the works is Porsche 356 panels as well as a few others!!

I'll be a busy boy, eh!!!

Randy
2005 ??? apparently navel jelly and Ospho are very similar.Ospho might be somewhat stronger ,just one application does itfor surface rust like your panel...funny thing is I was curious about navel jelly and googled it and this was the first thing that popped up explaining the application.sounds very similar to my process right down to the SPI...great artical Randy. BTW I finally managed to make that compound curve on my rollpan also met the guy in augusta you talked to for me.Thankyou.Mike from augusta...

Last edited by deadbodyman; 01-26-2010 at 05:34 PM.
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  #150 (permalink)  
Old 03-08-2010, 01:58 AM
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Acid

muratic acid while capable of removing rust does need
to be neutralized. Similar to that of tinning butter when
doing lead work, otherwise it will work it's way back up
through the paint. In some cases even having to heat
the metal/lead to get the acid to rise to the surface
between neutral washes with sodium bicarbonate and
water. Which for this reason (water on bare metal)
I use rust mort or similar
phosphoric acid products due to ease of removal prior
to priming.I use wax and grease remover before prime.
And I use etch primer on bare metal. But it all depends
on your satisfaction level, money involved, and ability to
find certian chemicals. Muriatic acid is easy to come by at
any store with pool treatment supplies.
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