Technical Penetrol for temporary stop rust

Good morning all. Long time reader, first time writer...

So I’ve read the forums on Penetrol and watched a few videos and here’s my backstory before the question. TLDR can skip down.

I inherited a 1950 Ford f1 that was primed but my grandpa never painted. It sat outside in San Diego for 10 years, majority under a car cover but it still got surface rust. I’ve been cleaning the rust off now. I’d say 80% of primer is still solid but rust has formed where bare sheet metal is showing now. I looking for a way to seal it while I save up to have it painted. I have tried Gibbs oil but living in Houston it’s humid all the time and the spots rust return after about a week. I’ve seen lots of other options like WD-40 and linseed oil but I’m looking for something that won’t affect painting later.

My question is:
If I apply Penetrol will it affect my ability to have it painted later (maybe a year or two down the road). And I would just sand down like normal paint prep process when I’m ready?

 

Why not just sand the 20% where the primer has failed and hit it with some aerosol cans of primer. You may be over-thinking this thing 'cause if you use any kind of oil based product you're going to have to remove it completely when you do get around to painting it.

 

Good question and yeah I for sure over think everything, I think... haha

I’ve thought about hitting with a can of primer, but I like driving it now and the primer is a white-ish yellow so from a distance the bare metal spots are not noticeable but if I hit with primer it will draw the eyes to it.

Plus the primer is chipping and cracking so I’m already going to have to sand it down to reprimer and paint anyway. I just don’t want to put something like WD-40 on it that will potentially mess up future paint job.

 

How are you storing the truck now? inside or outside?

I'd just leave it alone, until you can paint it. Although you say you already did some sanding...those areas, you can cover with some spray can paint, what type you use probably doesn't matter, but consider that something that is not primer, has a better chance of keeping rust from forming again.

 

Storing inside in garage and drive once a week if that. Yeah the small exposed metal parts start showing surface rust in about a week or two.

Yeah I was thinking if hitting it with some light clear coat rattle can stuff but idk how that would look. I bought some “Eastwood patina preserver” because it says it temporary seals for about a year and doesn’t seem to hard to remove.

But Penetrol’ing the whole thing seemed a way to seal everything at once while I save money. Any downsides to using it? If I sand it down a week or so before painting will it affect new primer and paint application?

 

Penetrol is a petroleum based material which is designed to be used with alkyd oil based enamels, spraying automotive paints over it will more than likely result in unsatisfactory results. HRP

 

Just wetting it down with penetrol won't do a lot. For it to do any real good, you'd have to sand the area quite well and then use maybe steel wool to scrub with the penetrol. If you're sanding that much anyway, you might as well just put a little primer and paint on it. Take it off later when you prep the whole car for paint.
If it was mine, I'd leave it alone until I was ready to do the whole thing in the right manner... or at least sections. It's hardly going to rust any more as long as you don't wait for years to do it.

 

that sounds like an oxymoron

 

If you can't sandblast...

After sanding, soak and scrub it with some muriatic acid to get the last bit of rust in the tiny pits. Protect your eyes, lungs and skin. Neutralize it with baking soda and water. Rinse and dry well. Sand it again. Prime and paint.

 

Yeah I think sand->primer->paint in sections maybe the best option. I’m getting a free 60 gallon air compressor in a couple weeks so looks like I’ll be having some fun in the 100 degree garage... haha

 

Much better than sandblasting in the 100° heat. HRP

 

I would strip each panel to bare metal, then shoot it with epoxy primer. That would seal it up. Regular primers are porous so it may be rusting underneath.


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Right answer IMNSHO.
'Normal' older primers would be lacquer based and soak up water like a sponge. Rust always starts under them if left to do so.

Epoxy primers seal the weather out and can safely be left exposed.. When you're ready it can be scuffed and coated with 2K primer/surfacer to prepare for paint.

 

Funny you should say that.
Guess what I'm doing.
But it's only 90° here.

 

I sandblast in the morning when it's still cool (under 80 degrees, usually). Although I did spend a few minutes under the hood yesterday afternoon, we had a nice storm blow in, and it cooled off.

 

That’s good to know on 2k epoxy primer. I’ll check that out. I think it might of had 2k primer on it, looked like a color summit racing sold. But the primer has just washed away in some places I. the weather over 10 years. That possible?

 

Clean and epoxy prime, or lps3 used on heavy jets and other a/c. I buy it by the gallon, used in on my fuel dragster frame, easy to clean and repair .

 

I had 2k primer on a car for 15 years, never any rust through, I had it down to bare metal before I applied the primer. When I got the car it had lacquer primer on it, lots of rust through.

I suppose if you put on a real thin coat of 2k it might not seal, but if you lay on a couple of good coats, it'll keep the car from rusting.

 

What about boiled linseed oil. It will wear off around six months , then applied another coat.

 

I’ve read about linseed oil. I was worried about my ability to repaint down the line, thus was thinking Penetrol and sand down later.

can you repaint after linseed oil?

 

Linseed oil is natural and will weather away. It is also easier and cheaper to apply compared to clear coat when trying to keep patina.

 

I use penetrol all the time. I'm a marine engineer and we use it for a range of things. For what you are proposing it is probably a waste of time and money. UV does break it down, it doesn't control the rust as good as a phosphoric acid paste. It will help the existing paint look good for a while, but so will a good wax. It wont hurt anything. Flood's advertised it for rusting galv anchors and chains but it last 2 or 3 months and then you are back to square one.

 

Ospho from the body shop supply store. Buffered phosphoric acid with zinc. Made for pickling bare metal that going to sit for a while before painting, easily sandable and supports good paint adhesion.

 

This is the first time I've heard Gibbs not doing it's job.

 

Epoxy primer Is porous. If it was nonporous it would be no need to add zinc. If moisture and oxygen cannot penetrate coating you cant create rust and existing rust cannot continue. They are now working on epoxy primer that has zinc flake and powder. The purpose of the zinc flake in layers would be to cut off the oxygen. I've been told that this is about a year away.

 

Yeah I’m surprised Gibbs isn’t working too. I spray on, wipe off, then 2 weeks later it’s rusted. I’ve tried spray on and waiting to dry and it rusts quicker.

I’ve also tried metal rescue dry coat and no luck.

My garage in Houston is about 90-100 during the day with about 50-70 percent humidity depending on day and rain.

 

I guess you should let the paint manufacturers know


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With Ospho will it eat / further degrade the current primer?

 

I think all you need is to get the metal clean. Then spray the spot with a rattle can paint, pick a color that matches.
Houston you have to much humidity and salt in the air from the sea ... impossible to keep the bare metal from rusting without oil ... and oil will affect a future paint job.

I am still learning myself and hope others have comments ... What I have found, ospho is great and it kills and turns existing rust into a primer you can paint over ... but it leaves a bumpy surface ... I think is great for frames but not body panels.

Muriatic acid removes all the rust to bare metal and does not hurt good paint, thin original paint it will remove. ... that stuff is harsh and you need eye protection, good respirator or hold your breath while working with it, if not properly neutralized it will cause more rust then what you started with. .... I personally only use it on a body panel on saw horses in the back yard ... would not use it anywhere near a complete running driving car and careful where you store the unused portion. Muriatic acid is a untrained Rottweiler held by a thin shoe string.

Currently I am trying straight phosphoric acid. It is the base for ospho, but it cleans to bare metal and leaves no primer residue. I am so far happy with the phosphoric acid, I ordered it on line from walmart, is 85% food grade and used for rust removal on commercial restaurant equiptment. Very safe to spray on rust, let it sit for 15 min and then scrub it with a scotchbrite pad and rinse with water ... gloves recommended but not needed, I did still wear eye protection.
I am still playing with it, look at my avatar and see what I have to play with. I bought 1 gallon and with shipping was $48 ... probably could dilute it with water and make 3 or 4 gallons with it ... I used it straight.
You can buy a gallon at home depot, but is diluted and weaker, I heard you can get 55% online for $16 a gallon.