I “think” I neutralized all of the OSPHO off my entire car tonight. It supposed to be a nice weekend here in Michigan and I’d love to get a coat or two of primer on the 41. Heres the steps I took: I re-wet the car with OSPHO one panel at a time, let it set a minute or so, scrub with a scotch brite pad, poured a liberal amount of soap/water over it to rinse, and then wiped off with a clean rag (new one each time). Then I came behind it and hit it with wax and grease remover. 80% of the car looks great, however I do have the dreaded white streaks and chalky finish in spots. Though it wipes right off with a dry cloth. Does this mean I missed some OSPHO? Is the best course of action to just restart the process in those areas? I also read on another forum to hit the whole car with 80 grit on a DA, wax and grease remover after, and then spray epoxy an hour later…. I know for sure next time I will steer very clear of this OSPHO mess, lesson learned… Any ideas on the next course of action? Thanks!!!
I think I would re-wet the places with the chalky finish, hit it again with the scotch brite pad, re-rinse and dry it off again. I suspect those places probably have some residue left, but I would not want to add any more OSOHO into the situation.
Ospho is one product I have never used. So I’m curious as well. But I’ve used metal preps. That looks like it still has residue. But I’ll learn from the guys experienced with the product. we plan to experiment soon with it
I use Ospho all of the time. I never do a single thing to neutralize it. That is not how it works. I follow the manufacturer's instructions exactly: http://www.ospho.com/directions.htm I wipe off any excess white residue with mineral spirits and a red scuff pad before painting. This hood was treated and allowed to dry. Once fully dry, I wiped it down with mineral spirits and a red scuff pad. This is how it looked once dry. If you look at the instructions, you will see that no mention is made of neutralizing it.
No offense, but I cannot fathom why you went through this elaborate process. I have been using this product for about 20-years, with great success, and I have never done anything but what the instructions on the container say. Zero issues. Zero paint job failures. No filler falling off.
I did read that, but I also saw this from Barry (from SPI) on many other forums "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. Next, then da car with 80 grit, clean with 700-1 wax and grease remover, let set an hour and coat with an epoxy." So I followed those steps.
I definitely don't want to add more OSPHO to the mix, but according to Barry at SPI I have to re-wet with OSPHO first, that's the only way to neutralize it. It's really hard to contain a liquid where I want it though on a car with some many curves haha. I tried a spray bottle and that gave me a lot more control, but I was still chasing it all night haha.
I am going to do the mineral spirits and red scotch brite tonight. I am just curious why their Tech Line would give such elaborate detail (in comparison), and their bottle says something completely different.
I too have used Ospho for many years, have always followed the manufacturers instructions and have never had an issue. I've never neutralized it, just scuff and wipe with prep solvent before prime/filler. I assume, the process of it reacting with the metal causes it to neutralize.
Got some big panels that I've used Metal Rescue and Evaporust on repeatedly, I'm at about 95% happy, but need to do Ospho, Rust Mort, etc. I just don't want to rinse with water. Tough to dry completely (in my case), and I don't want to introduce any new rust after all that work. After rinsing the Metal Rescue and Evaporust with water, I couldn't get it dry enough, quick enough, that I didn't end up with that golden sheen of new rust the next day, in a dry, climate controlled room. I used heaters and hauled ass, and still got the gold look.
I I'd never use 80 grit for any metal unless it was on an area I was planning to put filler over and wanted good grip. It just removes too much metal, and is a poor choice for good metal needing paint prep. For many years I've used paint stripper pads on my 4.5" angle grinder for paint removal, or to prep surfaces that had minor flash rust. They work extremely well, and wont remove metal. They will remove paint and filler quickly, and I can go over a whole car in about 5 hours if it doesn't have more than primer and paint on it. Might take a day on cars with multiple layers of paint. Once I've used the stripper pad all over I use degreaser solvent, and follow up with a tack rag before shooting sealer. I never let it sit overnight before shooting sealer as I'm afraid of flash rusting that can happen, and you wont even see it.
I read somewhere that Ospho is designed for oil based enamels. I usually use ppg dx579/ dx520 then rinse before priming. It leaves the metal bright with a slight blue/gold hue. I really don’t care for the residue left behind by Ospho. I asked SPI why they recommend using Ospho, then neutralizing it, they said that left over acid can keep the epoxy from catalyzing. They stated that they recommend Ospho only because the formula has never changed over the years. People tell me all the time that they spray right over the Ospho with no issues. I’ll follow the guidelines of the primer company because I don’t want to take a chance when thousands of dollars worth of paint materials are going over it. Dave
I've used Ospho on my last two builds using all SPI products afterwards and have had zero issues. The oldest paint job is now about 7 years old. This particular vehicle had bad overall rust that I blasted but not 100% clean so it wouldn't warp. I put the Ospho on, scrubbed it with a scotch brite pad and then wiped it off before it dried. This left a thin film. I didn't touch it for at least two weeks and then ran over the entire surface with a DA before following the SPI instructions for primer, etc. ...After all of this, I put a chicken in a burlap bag and swung it around over my head outside of the garage in the hopes that my paint wouldn't fall off. Obviously, this helped because my paint is still on the truck.
Damn. I sure am glad that I am not the only one doing the chicken thing! Has to be the only thing in 20-years keeping paint on vehicles that I worked on!
I've been painting cars since the early '60s, lacquer, acrylic lacquer, enamel, acrylic enamel and not much catalyzed new materials. I've never heard anyone using mineral spirits to clean prepped metal prior to etching or regular primer. Mineral spirits is 100% petroleum distillates and will block any adhesion between metal and paint. I learned to never even touch the surface with my hands after wax and grease remover and the first coat of paint material.
Help me out here, I thought Ospho was to keep metal from rusting? Or convert it? If it’s neutralized wouldn’t that defeat the purpose?
It converts Iron Oxide to Iron Phosphate. It leaves behind a rust resistant coating. If it is washed off with water, the coating is lost, and the metal is re-introduced to oxidization. So yes, if you take the unnecessary step of "neutralizing" it, you will partially, or fully defeat the protective purpose.
Nobody said that is what they are doing. You still need to clean your metal using all standard practices before applying primer. That is never not the case. Mineral spirits are used to remove the excess white coating, so that the surface is smooth. You don't actually need to do it, at all. It is just to get the surface smooth. As I have mentioned, I have been using this product for about 20-years, by the manufacturer instructions, and others have too, all without any negative results. We cannot all have accidentally had repeated success. Of course, we're all using modern catalyzed products. Then again, I also primer right over surfaces that have been treated with Gibbs Oil, after wax and grease remover, as is, again, standard practice, and I have had zero issues there, too.
IMO, the difference in instructions is due to the paint chemistry,, SPI (Barry) is very clear that acid is the enemy of his epoxy. That is not true of all epoxies. For instance, Kirker's Enduro Prime is speced to use directly over their acid based prep. Like all painting products compatibility is important. I've used Ospho under Kirker many times. Just apply, let dry lightly sand or red pad and spray.
Used a metal prep product made by Dupont years ago when I painted the 51', still have some left over somewhere in the cabinet, can't remember the name of it, it smelled like windex with alcohol, was blue colored. It contained a little bit of acid and was concentrated. Mixed it in a bucket and used a scotchbrite pad with it to scrub the metal. No water rinse, just put the mix in a spray bottle and sprayed the metal down after hitting it with a scotchbrite and wiped dry, air dried out the cracks and crevices. No white chalk residue when done! Worked great!
That's the main reason that I picked the Kirker honestly. I had read from many forums/people that it was good to use with OSPHO so my thinking was either way OSPHO or none, I was covered and my primer would stick haha.
I'm 5 days post-primer and I am happy to report my primer is sticking haha. Laughable and basic for most of you, this feels like a huge win and large step for a beginner like me. Thank you everyone for all the help and feedback!
You obviously have never used it with HOK EPOXY PRIMER! I SCRUBBED THE ROOF OF MY FORD THAT WAS STRIPPED TO BARE METAL WITH OSPHO.DIDNT NEUTRALIZE IT.THE NEXT DAY THE PRIMED WITH HOK KP2CF A GREEN EPOXY PRIMER.THE PRIMER CAME OFF IN SHEETS!
With Ospho I like to apply it on a sunny day or use a heat lamp to dry it then spray primer right over it, haven’t had any issues
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