Nother, maybe dumb, question (OSPHO)

dodge trucker

Tractorologist
Senior Member
Member
I'd been hearing about this stuff for years but never had a place around here to get it.
I was in a farm store by work that had recently closed and sold and has since reopened, and found it while looking for something else.
So I bought a quart to try.
I have been looking it up and now I have more questions about it than I ever did.
Mainly this.... I've seen complaints about paint and primer not sticking to it, having to remove it if it gets painted over, and then other conflicting posts saying to get all the loose paint and loose rust off, apply OSPHO, let dry and have at it with paint and primer. OSPHO will tell you that it's use helps with paint bonding where these complaining users, get responses like "well you should have removed the OSPHO before painting and you wouldn't have had a problem". Exactly opposite answers about the stuff.
I just used some for the 1st time earlier today on a steel push mower deck, something I really don't care about alot, if it holds up on it not as a test piece. My thoughts were to spray over the OSPHO with either EZ slide paint or some POR 15 as this is the bottom side. Thoughts?
 
Does the OSPHO have to come off to paint? I have some truck sheet metal that I was thinking about trying this stuff on before repainting it.
 
On my trailer that i used it on, I found out you don't want to let it get wet or use in high humidity as it had a white powder on it
 
So what's the deal about the white powder? Has that got something to do with paint sticking or not sticking? Have to sand before applying other paint? I noticed spots on the his deck that are that way while other areas aren't.
I have a neighbor whose husband died several months ago ask me to check out her tractor, a sears DGS 6500 which has a 54" deck. Started out as a belt replacement but this thing hasn't been scraped in a couple of years, and blades need sharpening, so after jacking up the front by way of 1 arm of my 2 post hoist and eating Deck scrapings for a few minutes I decided to pull the deck and flip it over, instead and ended up hitting it with a Milwaukee grinder and wire wheel. I ended up having to go by work to get my needle scaler to use on the front wall of it, if I don't do something with it now she may not have a deck to mow with come spring, let alone finishing this season. So I have deck number 2 to experiment with.
so should I continue with the OSPHO on this deck or skip straight to the POR 15?
 
I think the powder would cause paint sticking issues. I just used a hand wire brush and went over it and blew it off with air. Paint is doing well on the trailer.
 
I think the powder would cause paint sticking issues. I just used a hand wire brush and went over it and blew it off with air. Paint is doing well on the trailer.
Here's what I do, and I have used it a lot. I sand down sheet metal to bare, scrub any rusty spots with ospho and scotch brite pads, let dry overnight, the areas that have turned black were rust spots. I then resend to get ospho overcoat off, and spray epoxy primer, like dp90, over whole piece. Have done this with car bodies and never had any problems. Ospho is used extensively in coastal areas, so that should tell you it's good stuff. But don't get any in a cut on your hand!!!
 
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