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The Ospho problem

17K views 29 replies 12 participants last post by  deadbodyman 
#1 ·
After spending hundreds of hours building my 59 BelAir, it was really hard for me to take a knife to the paint, but Today I finally drummed up the energy to chip off this D*** blister on top of the fin, below the B pillar. I was pretty sure of what I would find, and it's now confirmed that the Ospho that I sprayed inside the fender caused this. I carefully lifted the blister off so I could see exactly what was under there and where the separation occurred. as you can see, there's lots of the black powered remains of Ospho. I repeat, there was NO Ospho applied to the outside sheetmetal anywhere on this car. the only reason I applied it inside this area was due to the almost total lack of access by any means short of dismantling the inner sheetmetal structure in that area, and there was some surface rust that I felt the need to "kill". the Ospho was sprayed inside well after the Epoxy was sprayed on the outside. it appears clear that some Ospho found it's way up through three pinholes in the sheet metal. when I sprayed the epoxy it was applied to well cleaned shiny metal.
I've spot blasted the area and am in the process of repainting. I'll blend the base and clear the whole top of the fin. my only concern now is if this will reoccur. I'm sure there are places that Ospho can be used to good advantage, but I'm not smiling on it at the moment. :nono:

Russ
 

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#2 ·
Oh dear God that is heart breaking! DAMN! It does have it's place and you would have thought that would have been a good place for it, but damn. The crap is the rust holes that can come through from the inside on these old cars, it really is the craps. And if you hadn't put anything in there, if there were pin holes they would have done about the same thing anyway. Honestly, don't beat yourself up for using the Ospho because if there were pin holes, this would have happened anyway.

Brian
 
#4 ·
If you don't fix those pinholes the problem will come back, even if the ospho is completely neutralized, just humidity will start the rust monster again under the paint. You can't leave holes there even if they are invisible to the naked eye. I'm hoping you already know this and it is covered under your "prep" statement.

Great looking car, by the way .
 
#6 ·
Here's a photo of the offending structure. it's the plate at the top of the inner fender well that closes off the area between it, the fin area of the 1/4 panel, and the trunk latch structure. this plate effectivly blocks any access to the inner 1/4 ahead of that. by removing the rear seat, and upholstery panel from the 1/4, the closest you can get to the other side of the plate is about 2'. I built several "special tools", with 80 grit attached, to reach in there and clean off any surface rust that I could get to. when I had it as clean as I could get it, I sprayed (heavily) the Ospho with a little pump sprayer and a short wand.
I was hearing stories of rusted parts being sprayed and then left outside in the weather for years without further rust. etc., etc., etc. well huummmmm. ya right. :(
 

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#7 ·
I'm saying that the outer skin where your paint bubbled will either have to have the pinholed area carefully brazed up, or the pinholed area cut out and new metal welded in its place...not the inner structure, the outer quarter skin where the paint has bubbled, it has bubbled because there are pinholes allowing moisture to get under the paint from the underside.
 
#8 ·
That is truly heartbreaking Russ.

I have to agree with Eric though. Ospho or no, this same issue would have happened if the rust can get through to the paint. Minor pin holes spell death to a paint job. There is just no substitute for getting rid of the rust even if that requires opening up the panel and/or replacing the rusty section.

You have a beautiful car . When you first posted the pictures of it I showed it to my wife because I knew she would just love that color.

I hope the effected areas are small enough that you can successfully correct this issue.

John
 
#9 ·
Interesting comments about the pinholes.... I was hoping that using 2-3 good coats of Epoxy would cover these pinholes and keep water from coming through the inside and blistering the paint. Ive had a few cars that where never Epoxied, had pinholes and 1/8 inch holes that where covered by bondo.. 15 years later and never had any paint issues. Interesting thing is that these holes were under a fender on cars in which I'm sure water hit the underside.

Did I just get lucky?
 
#10 ·
I have very similar thoughts and experiences, but I to am listening to the more experienced, and trying to learn. I may well be wrong, but it was my belief that water wasn't what made this blister, but rather the Ospho coming up through the pinhole and getting under the epoxy primer. the reason I believed this was due to the black powdery Ospho residue between the surface metal and epoxy primer. also this car has never been wet since painted, which was only a month or two ago.

today I finished my "patch", and if the blistering comes back then I'll have to go the major surgery route. I figure this is worth a try considering the difficulty involved in the alternatives. what I've done was to use a very thin skim coat of all-metal over the affected area to seal the pin holes. after block sanding I shot a spot of epoxy primer, covered by a slightly larger spot of base coat, and then re-cleared the whole fin. I have very little experience with blending, so I'm actually very pleased with the finished product. when this pic was taken the clear was still tacky, so by tomorrow it should even be smoother. I'll cut and buff in a couple days and then wait and see what (if anything) happens.


Russ
 

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#13 ·
The Ospho applied to the back side of a rusty panel will not penetrate through the rust to neutralize it all the way through. For the Ospho to work, it must be able to penetrate all the way to the non rusted steel and that is going to require abrasive action. If the steel is not cleaned on both sides and any rust remains it is just like a cancer that continues to grow.

I personally don't think the Ospho would creep under quality epoxy that was properly prepared and applied to clean metal but if there were pinholes in the metal and it is not immaculately clean (and coated) on both sides the rust is going to come through and will creap under anything. This is the challenge when working on a rusty vehicle. The rust must be removed one way or another. Cut out, removed with acid, sandblasted, etc, etc. Just coating it is not going to fly. At least I have never seen long term success.

John
 
#15 ·
The Ospho applied to the back side of a rusty panel will not penetrate through the rust to neutralize it all the way through. For the Ospho to work, it must be able to penetrate all the way to the non rusted steel and that is going to require abrasive action. If the steel is not cleaned on both sides and any rust remains it is just like a cancer that continues to grow.

So what good is Ospho if you must have the metal immaculately clean for it to work? why bother. the rust I referred to was just surface rust to begin with, and I did use 80 grit on it the best I could, with the limited access. there was certainly no scale remaining or anything like that.


I personally don't think the Ospho would creep under quality epoxy that was properly prepared and applied to clean metal but if there were pinholes in the metal and it is not immaculately clean (and coated) on both sides the rust is going to come through and will creap under anything.

John
Huummmm. so how do you explain the black powdery substance between the epoxy and bare metal? I can't just ignore what I'm seeing. it was shiny bare steel when the epoxy was applied.

I don't mean to be argumentative, but I know my prep work was as good or better than any I've done in the past, on many cars before this one that never had this problem. the only difference was the use of the Ospho inside the body panel of this one.


Russ
 
#16 ·
I can help but it'll require a phone call I need to know exactly what you did ,what you used, starting from bare metal. just Pm me and I'll give you my number. I've also ran into a case where the epoxy didn't stick at all and there wasn't any ospho on the car anywhere, the cause that time was spraying the epoxy when it was too cold. this was about the only time I've ever stripped a car and DIDNT use ospho that's when I had a problem...you can also send an email to skyco explaining your problem maybe they can help. I think the guys name is over there is Steve Pitcher or Pritcher, another car guy
 
#17 ·
Thanks DBM, but I guess I've already done all I can do, unless something pops up again in the future. with summer coming on, and the car likely to see a lot more hot summer days soon, it will be put to the test ;) . this was the only area (both sides of the car) I used the ospho, and the other side of the car looks fine.

So you've also seen similar issues of Ospho lifting epoxy on the opposite side of a panel??

Cheers,
Russ
 
#18 ·
NOT A FAN of OSPHO!

When I restored my 62 ford galaxie I stripped to bare metal washed with Ospho and rinsed as per the instructions then I applied 3 coats of house of Kolor KP 2 CF epoxy.The epoxy peeled off and I had to strip it.Now im restoring a 56 crown vic.I will go to bare metal than epoxy no ospho for me.
 
#19 ·
Ospho, is a great product for automotive if used right, we give scare warnings because we want people to call so we can make sure they know how to neutralize it, so no problems will arise.
Only one way to use and here it is:

Use as needed and apply as many times as needed to get the spot clean, let dry and leave for months if you want, don’t matter.
To neutralize the Ospho MUST be wet, so if dry, re-wet with itself and let set one or two minutes and with a clean rag and water, wipe off like washing the car and then dry.
Extra safety precaution then da car or spot sand with 80 grit, clean with wax and grease remover and coat with an epoxy.

Notes of interest (maybe)
If you try and sand dry film off you will lose 40-60% adhesion (per adhesion tester as some will imbed itself in metal and amount depends on how long the Ospho has been on panel as we do know acid films degrade with time but due to many factors we cannot pinpoint a time frame.
Tape is not a test, use razor scraper after 7 days or an adhesion tester if you have an extra $6000 to spend.
How does it fail? Here are a few calls.
Washing car and hose bounced up, hit car and paint bubbled.
Kids finished ball game and ran by car and tossed ball gloves on hood, next day two big bubbles.
Wife got bag out of trunk, closed trunk and set bag on truck to play with keys, next day a bubble there.

My FAVORITE TECH CALL at least once a month, my body filler dried and sanded great but when I got to metal is was gummy, DO I HAVE A BAD HARDENER? Nope only one thing, you applied it over an acid film..
 
#20 ·
Barry,

All great information I appreciate you taking the time to add your input. the question still lingers in my mind, however, is it possible that Ospho being applied to ONE SIDE of a slightly rusty panel would lift the cured epoxy primer (via pinholes etc) that was sprayed on the other side of the panel a few days/week prior?
I'm pretty sure I've taken care of my problem this time, but it would still be helpful for others to know.

Thanks again Barry,

Russ
 
#22 ·
OK, I have to correct myself, I have done some research on this and I must change may answer to could have happened.
What I was told is there are a few epoxy resins that will do this with acid, even if 6 months old.
I was told of a couple of companies in the automotive refinish section that use these but that don't mean there not blended to not do it, could be but anyway to answer your question YES it could have happened.

Sorry for the bad info.
 
#25 ·
Deadbodyman. I need to ask you several questions about Ospho. I can call you if that would be better.

I ended up applying OSPHO everywhere on my car/utility trailer this past Friday night. It had been sandblasted this week. All day Saturday, there was no rust anywhere that I could find. When I woke up this morning, it is now covered in surface rust. What are my options to get this thing ready for primer and paint. Mind you, this isn't going to a show piece. Just used for hauling hunting, camping supplies, riding lawnmowers, 4 wheelers, etc down dirt roads and the brush. Can I just use a rusty primer to get it ready? Or do I need to reorder a gal of OSPHO as I am now out, and redue the whole thing over?

Thanks.
 

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#26 ·
There is nothing but nothing better than sandblasting and then epoxy primer. There was nothing better that you could have done. Now, I say have it sand blasted again. With all the nooks and crannies that the Ospho could caught in, I say wash it good with water and blast it again.

Brian
 
#27 ·
phosphoric acid is one of the best cleaners available . used correctly it will clean metal very well . as long as it is rinsed while wet it is no problem . after cleaning you will see an orange tint on the metal . this tells you it is clean .
 
#29 ·
So after posting the earlier message I started calling around for some more OSPHO. There wasn't any around for 50+ miles, so I had to order a gallon.

Needless to say, I decided (since I hadn't heard anything back yet) to get a wire wheel out and get as much rust off as I could. That way it would at least slow the rust down till Wednesday (as I took the wifes SUV out of the garage and moved the trailer in), and I can recoat it then.

So after wire wheeling the whole trailer but the inner fender wells (no rust) and wheels (buying new ones), it looks much better. I think in the long run I am glad this happened. As I found a lot of black parts (converted rust) that I was able to remove. Now the trailer is the grey color it was before it rusted over night. Granted you can still see some rust bleed through. Or at least I think it rust bleed through?

My next question is: can I just go ahead and use oil based Rustoleum primer product after I use Prep All? Or do I need to wait and wash it again in OSPHO?

Thanks for all the help. Especially since it's just a trailer and not car/truck.
 

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#30 ·
what you did when you "sprayed it on well" is convert the rust.
rust converting is no good, you want to REMOVE the rust. Ospho removes rust but its a lot of work ,what you did is the same thing a lot of people do they spray it on like its some kind of magic solution and just leave it ...THEN when the problems pop up that everyone warned you about you blame the product ,it couldn't possibly be improper application,I did it all myself...:nono: listen to the pros that use it or don't use it at all. at least you've learned something.(the hard way) ...lesson #1 improper application of acid products are the #1 cause of paint failure....
 
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