stripping a patina Duster hood

fishmens67

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I'd hit it with rust bullet metal blast conditioner and then apply epoxy primer.
 

Fast340cuda

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What yo have going there will probably outlast all of us. Please hit it with some media blast and a good cleaning before the epoxy coat.

I see some black in that pic and understand what you are saying. Unfortunately I don’t have another pic of the area after the second application but it is pretty clear that this process does in fact remove the rust. Just takes a few applications!
 

harrisonm

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so it doesnt actually remove the rust in the pits?

I wish I could remember the name of the product I used on my roof. It came in a plastic spray bottle. It had some kind of acid in it and gloves and good ventilation were a must. To answer your question, NO, it does not remove the rust. It was a converter. It converted rust (iron oxide) to a black compound that is NOT rust. I think I wiped the roof with lacquer thinner and then used 80 grit on a DA. It's been a while, but I think that is what I did. Then Epoxy primer. It has lasted for a long time.
 

mad dog

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so last night i went to you tube to watch Ospho videos, i feel more comfortable useing this product now... im still going to try to remove what i can with evaporust and paper towels and what ever is left will get a dose of ospho.. i was also reading the tech sheet on SPI epoxy primer and thats the only rust convertor they recommend
 

barbee6043

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No and there's no way in HELL to get all the left over Ospho neutralized, either.

Be careful that you do get all the Ospho neutalized or there can be issues later with epoxy primer.
I have not had issues as long as it was WELL neutralized. Just me. Rust is a *****!
 

RustyRatRod

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Be careful that you do get all the Ospho neutalized or there can be issues later with epoxy primer.
I have not had issues as long as it was WELL neutralized. Just me. Rust is a *****!
Hay you hush all that up. lol
 

Bodyperson

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Evaporust at work.
20170221_100715.jpg
 

mad dog

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so this morning i went out to the hood and the evaporust soaked paper towels were all rust stained, i removed the paper towels and the plastic sheets and scrubbed the hood with a red scotchbrite pad and 90% of the rust came out of the pits... i put new paper towels down and soaked them again for another round of evaporust, i will then follow up with the Ospho.... ive heard many ways to neutralize the ospho from the FABO family and im getting a little scared and overwhelmed that i wont neutralize correctly.. please one last time ... what is the best fool proof way to do this step, i dont want any issues with my epoxy...Rich
 

barbee6043

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^^ One place I have seen Ospho mentiond (warned) is Southern Polyurethanes. They warn about the effects that can come of it Only neutralize method I have seen is go back and wet it good sit awhile of NOT dry, rinse thoroughly with water. ( Be advised back in my school days I fluked Chemistry several time). I have read that some epoxy primers contain some type of acid and there is a reaction, sometimes delayed for months.

I painted a 62 Dart, a few years ago it had sat out in the 110 degree Tx weather forever, and the top side was down to surface rust sheetmetal and pitted. I sanded it best I could, even ran the big wire cup on the right angle grinder over it good. I wiped it down good with Ospho. I thought I neutralized the whole car , maybe NOT!?? Epoxy primed ( forget what brand), epoxy primed it high fill urethane, usual sand, block I sealed it and shot it with acrylic urethane single stage. About 6-8 months later, I noticed some small or tiny blems looked really like I had some dirt in the topcoat.
It might well have been a delayed ration to the Ospho. Dunno.
It was a $1000 more door, not destined to ever be perfect anyway.

Way back maybe 10-12 year ago, I had a 63 Dart, good amount of surface rust on the hood. I sanded and cleaned it best I could and wiped it good with Ospho. I dreid about a day. I never knew to neutralize the stuff. I was not ready to tackle its body work and just wanted to protect the hood from rust and I had NO epoxy primer that day and was not making a 100 mi trip after any. I shoot it with RustOleum!!!! Ha fter it cured, I noticed some small areas where the paint had '
wrinkled". But it was stuck on well. That hood sat outside for another 6-8 month before I decided to tackle its body work. That RustOleum was ON THERE> I could not hardly DA the damn stiff off even where it had wrinkled. Yes it had fabbed because that is what it is.

About 30 years ago, I had drug home a 64 Sport Fury. Lots of surface rust, we DA ed that sucked with in of a heart attach used the best PPG epoxy primer, all the usual steps about a year later I noticed signed that it wanted to rust some under all that!!!! Thats when I learned of Ospho.

Years ago I used some metal cleaner that was from DuPont. Not sure how well it killed rust, but seems like a nice product. Stupid expensive.

Every body guy I have ever talked about such metal cleaning, always said, stay away from any.

Damn if you do and damn if you don't???
 

harrisonm

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so this morning i went out to the hood and the evaporust soaked paper towels were all rust stained, i removed the paper towels and the plastic sheets and scrubbed the hood with a red scotchbrite pad and 90% of the rust came out of the pits... i put new paper towels down and soaked them again for another round of evaporust, i will then follow up with the Ospho.... ive heard many ways to neutralize the ospho from the FABO family and im getting a little scared and overwhelmed that i wont neutralize correctly.. please one last time ... what is the best fool proof way to do this step, i dont want any issues with my epoxy...Rich
I want you to know how impressed i am with your research, your work and your attitude. Far too often lately, we have had people ask questions and then get snippy (putting it mildly) with people who offer ideas they didn't care for. Your replies were all appreciative. Plus, I like the way you are researching this problem to find the best solution. Then, I really like the way you have kept us advised on the progress of your project.
 

Bodyperson

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I want you to know how impressed i am with your research, your work and your attitude. Far too often lately, we have had people ask questions and then get snippy (putting it mildly) with people who offer ideas they didn't care for. Your replies were all appreciative. Plus, I like the way you are researching this problem to find the best solution. Then, I really like the way you have kept us advised on the progress of your project.
Plus, I'm learning and doing more research myself.
 

Phreakish

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Neutralizing acid makes water and salt. Salts aren't ever good for corrosion protection or paint adhesion.

The pros seem to recommend rinsing the ospho before it dries, or re-wetting the surface with ospho and while it's still wet, clean thoroughly with soap and more water. The water rinse/flush is the critical part. It's how every plating shop cleans the solution off of phosphated parts. It's impossible to flush with too much water.
After the cleaned surface dries (it should be helped with towels, compressed air, leaf blower, etc) sand it with 80 grit to remove any loose residue, salts, and excess Phosphate, then wax/grease remover and then paint.
The sanding step is critical too, because both iron oxide and bare iron will turn to Phosphate, but at different rates, and some of it will only occur in the solution and not on the metal. Since they're crystals they don't like to wipe or wash away. Sanding will level out the new crystals and help loosen up the "flocked" ones too.
I've mostly done manganese Phosphate, and have experienced lots of these issues with adhesion or just a bad coating. Iron Phosphate, which is what ospho makes, is similar.
 

harrisonm

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I wish we had YouTube when I started doing body/paint 45 years ago. I learned a little from books and a few people showed me a few things, but 90% of what I have learned was from trial and error.
 

mad dog

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harrisonm, thanks for all your advice, im a firm believer that listening to advice from people that are knowledgable and experienced backed up with some of my own research will get the job done right the first time... im thinking that while im waiting for the ospho to get here i will drop the hood off at my media blaster to get the backside bracing cleaned up, hes pretty careful and knows what to blast and what not to blast.
 

mopowers

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harrisonm, thanks for all your advice, im a firm believer that listening to advice from people that are knowledgable and experienced backed up with some of my own research will get the job done right the first time... im thinking that while im waiting for the ospho to get here i will drop the hood off at my media blaster to get the backside bracing cleaned up, hes pretty careful and knows what to blast and what not to blast.

Did you order the ospho online? You're local hardware store likely has it as well.
 

mad dog

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i checked at Ace hardware and they were out... it will arrive this week, just in time for the weekend
 

mad dog

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ok guys i got the hood back from my blaster, he was going to do the back side for me...
so now the top of the hood is DA'd and the underside is blasted, i just put a coat of ospho on both sides of the hood, im going to wait the 24 hours and then the directions say to brush away the powdery substance thats left behind and wipe with a solvent type of wax and grease remover and then prime and paint... no where does it say to use water to neutralize, im not opposed to do that as you guys recommended thats the way to go, im also afraid that my fresh media blasting will immediately flash rust, i guess im just getting cold feet and am looking for some reassurance ... am i still on the right track?... thanks Rich
 

mopowers

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I wouldn't even let it dry. It's much easier to clean up when it's still wet. Plus, if the metal's been DA'd and/or blasted, it shouldn't take that long for the phosphoric acid to clean up what little rust is left. Maybe it's just me, but letting it dry just results in more (and usually unnecessary) work. The "white powdery substance" isn't as easy to get off as they make it sound. From my experience, it's a pain in the *** to remove.

If it was me, I'd apply the acid, let it sit for 10 mins and wipe it off with a wet sponge and a bucket with lots of fresh water, then repeat as necessary.
 

mad dog

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i was just reading a forum based on this and ospho users said the same thing, they said to NOT let it dry and if it does dry to reapply ospho and wipe it clean and use plenty of water... i was thinking that the ospho needed 24 hrs to do the rust conversion, 10 minutes doesnt seem long enough, maybe it is....
 

mopowers

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i was just reading a forum based on this and ospho users said the same thing, they said to NOT let it dry and if it does dry to reapply ospho and wipe it clean and use plenty of water... i was thinking that the ospho needed 24 hrs to do the rust conversion, 10 minutes doesnt seem long enough, maybe it is....

How bad is the rust?? You said it was DA'd and blasted? There shouldn't be much left after that. I think you'll be surprised how quickly that **** works. For large sections of sheet metal, I get what I can with a scotchbrite roloc and hit what's left with a spray of acid, let it sit for a few mins and clean it off. That's the process I used for the roof panel in post #12. Only a few small spots needed more than one application.
 

mad dog

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rust isnt bad now, its just the pits that are holding the rust... its dark outside now so i cant do anything till morning, that would be about a 16 hr exposure for the ospho to work
 

barbee6043

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Ospho. I personally, apply good wet cover, I let it sit over nite. I take scotch brite and get rid of the phosphate dust, blow it off and apply good wet over and let it sit for 15 minute but not dry, and rinse well with plenty of water. Might even be smart to neutralize twice. I have also used it where I welded and ground down the welds, as I figure it is so easy to have microscopic pin holes where I welded. Neutralizing is the key.
II admit I can be "anal" about rust. :realcrazy::BangHead:
 
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mad dog

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so i waited overnight and the ospho was dry, i reapplied the ospho and let it sit for 20 min and made sure it did not dry, i then scrubbed the **** out of the hood with a red scotchbrite to make sure i got everything moving and then i did two heavy scrubbs with Dawn and warm water followed by a long rinse with the garden hose.
i then watched my hood flash rust before my eyes, i got to admit im not sure the ospho was worth it, i now have to take off all the surface rust off both sides of my hood... i already have many hours getting it to this point but it is what it is, tomorrow will be epoxy time followed by 2k high build... i guess if it was easy it wouldnt be so gratifying when we finally turn the key...Rich
 
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