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Technical Por15 over ospho?

Discussion in 'Traditional Customs' started by Bewarethebob, Oct 15, 2020.

  1. Bewarethebob
    Joined: Jul 5, 2020
    Posts: 6

    Bewarethebob

    I've read some mixed reviews on other site's but I want your guys opinion. I used ospho inside my door and down in my wiper cowl to stop rust that I can't really get to. Can I paint por15 over it or what steps do I need to take before paint with por? IMG_20200908_212420_369.jpeg

    Sent from my SM-N960U using The H.A.M.B. mobile app
     
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  2. chubbie
    Joined: Jan 14, 2009
    Posts: 2,318

    chubbie
    Member

    Call the POR store they will talk to you
     
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  3. Bewarethebob
    Joined: Jul 5, 2020
    Posts: 6

    Bewarethebob

    Por said to use their metal prep and then paint, shouldn't have any issues from the ospho... we'll see

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  4. dudley32
    Joined: Jan 2, 2008
    Posts: 2,136

    dudley32
    Member

    I have painted over Ospho on frames and floors and the like with very good results...I've never used POR15.
     

  5. mr.chevrolet
    Joined: Jul 19, 2006
    Posts: 7,843

    mr.chevrolet
    Member

    you should use OIL based paint over OSPHO. i use Rustoleum when i do OSPHO CIMG4766.JPG CIMG4784.JPG
     
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  6. Pats55
    Joined: Apr 29, 2013
    Posts: 523

    Pats55
    Member
    from NJ

    Yes you can use the POR 15 over ospho. This silver is more effective than the black and apply 2/3 coats. I wrote the tip sheet and introduced them to metal prep in 1987. They still use my tip sheet today.
     
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  7. gsnort
    Joined: Feb 5, 2008
    Posts: 254

    gsnort
    ALLIANCE MEMBER

    Ospho is a mild solution of phosphoric acid. The acid changes iron oxide, rust, into iron phosphate. I've used it with much success.
     
  8. nunattax
    Joined: Jan 10, 2011
    Posts: 2,714

    nunattax
    Member
    from IRELAND

    POR15 works best painted over rust.if your parts arent rusty leave them out in the rain for a bit then paint over the rust,great stuff .
     
  9. NAT WILLIAMS
    Joined: Nov 7, 2008
    Posts: 102

    NAT WILLIAMS
    Member

    Don't know if it's right but for the last 20 years I clean the inside of my doors and quarters and paint Por-15 in the bottom up about 3 inches on the inside of the doors. I stuff tiny rolled up pieces of paper towels in the drain holes. If I still smoked cigarette filters would work better.
     
    belair likes this.
  10. pirate
    Joined: Jun 29, 2006
    Posts: 671

    pirate
    Member
    from Alabama

    I have used the POR 15 metal prep which I suspect is phosphoric acid not much different from Ospho which is diluted phosphoric acid. The oxide formed from phosphoric acid is actually a very good surface for paint to stick to.
     
    clem likes this.
  11. Almostdone
    Joined: Dec 19, 2019
    Posts: 591

    Almostdone
    ALLIANCE MEMBER

    I can’t imagine a more informed answer than the one from Pats55.
     
  12. @Pats55 Can you elaborate on the difference between silver and black please? In what way is silver more effective?
    Just curious....
     
  13. jaracer
    Joined: Oct 4, 2008
    Posts: 1,228

    jaracer
    Member

    I haven't found anything yet that POR 15 won't stick to. And once it's stuck, it doesn't come off.
     
  14. cjsavage
    Joined: Oct 28, 2011
    Posts: 58

    cjsavage
    Member
    from eastern nc

    I made the mistake of using POR 15 on a new piece of unprepared cold rolled 18 gauge. Looked great, but peeled off in perfect sheets. I thought for some reason it would etch in. It needs something to grab on to, like rust, or the metal should be sanded.

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  15. THE FRENCHTOWN FLYER
    Joined: Jun 6, 2007
    Posts: 3,808

    THE FRENCHTOWN FLYER
    Member
    from FRENCHTOWN

    Most "new...unprepared cold rolled 18 gauge" steel is pickled and oiled at the mill to prevent corosion before it gets to the customer. If you did not clean the metal thoroughly with solvent I would not have expected anything to stick to it.
     
  16. Pats55
    Joined: Apr 29, 2013
    Posts: 523

    Pats55
    Member
    from NJ

    When Mo Bay chemical developed this permanent type bridge primer it worked on 2 principles. It had to block both moisture and oxygen. The resin used is heartened by moisture and is completely waterproof. The next part was how to block the oxygen. Non leafing aluminum flake in layers cut off the oxygen. They named this coating system The 3 coat polyurethane system. 2 coats of the silver primer followed by a topcoat. When you remove the aluminum flake and substitute a pigment you're no longer airtight.
     
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  17. cjsavage
    Joined: Oct 28, 2011
    Posts: 58

    cjsavage
    Member
    from eastern nc

  18. Pats55
    Joined: Apr 29, 2013
    Posts: 523

    Pats55
    Member
    from NJ

    sandblasting the surface is the optimum surface prep , but if sandblasting is prohibited by law or not practical, remove loose scale with a stiff wire brush, wire wheel, or grinder.Surface should be decreased . For previously coated surfaces, remove any loose, cracked, or peeling paint with a wire brush or grinder and scuff with 180 grit sandpaper. Stir thoroughly before use and wear protective gloves.
     
  19. El Caballo
    Joined: Mar 3, 2001
    Posts: 5,913

    El Caballo
    Member

    Is POR thick and would it clog the drains in the cowl?
     
  20. 62SY4
    Joined: Oct 30, 2009
    Posts: 102

    62SY4
    Member
    from Irwin, Pa

    My experience is POR15 is somewhere between unthinned enamel and latex paint. I'm sure @Pats55 could provide a Zahn cup number, but I've used POR silver inside doors by pouring and pushing it around with a brush to insure coverage; it ran out of the drains (stamped depressions in the inner structure) with no clogging. I've yet to try the Mastercoat I bought earlier this year, but I expect similar or better results.
     
  21. Is the silver the same as the tank liner?
     
  22. Pats55
    Joined: Apr 29, 2013
    Posts: 523

    Pats55
    Member
    from NJ

    Moisture cured urethanes viscosity changes dramatically each time the containers opened. Fresh material is generally thin. Each time you open the can and moisture is introduced the coating will get heavier. Initially Zahn cup#3 is generally 22 seconds. When doing seams reduce the 1st coat by approximately 10% and follow it up full-strength on a 2nd coat. You can slip something up into the drains to keep them open if need be. I personally flood the joints with either rust remover/prep work or Tru cure 1st for a couple of days. There are 3 different viscosities available through master coat. You have the regular which is a latex consistency, 2nd one is this Slim sprayable from the container with a 1 point 8 tip and the extreme which is a paste to fill in heavy petting
     
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  23. Gary Addcox
    Joined: Aug 28, 2009
    Posts: 2,448

    Gary Addcox
    Member

    We wiped Ospho over the frame rails to kill the surface rust on new metal, primed, then painted with Victory Red acrylic urethane. Frame is like new from 2010.
     
  24. Pats55
    Joined: Apr 29, 2013
    Posts: 523

    Pats55
    Member
    from NJ

    It would be similar. I have not been involved with POR 15 since 1988 so I would not be able to tell you what type of pigments they are using. There are 2 types of silver pigment there is leafing pigment which is usually used as a topcoat. Non-leafing pigment is the primer pigment. You can tell a difference by rubbing your thumb on the surface if it turns black it is non-leafing pigment.I hope this helps
     
    Last edited: Oct 30, 2020
    62SY4 likes this.
  25. The tank liner dries very smooth and glossy, surface doesn't react to rubbing.
     
  26. Pats55
    Joined: Apr 29, 2013
    Posts: 523

    Pats55
    Member
    from NJ

    That particular formula is difficult paint over. Use it for your welded seems inside the doors etc. I wish I could sent you can but shipping to Australia is astronomical
     
  27. Thanks, but I'm not the one wanting anything.
    POR15 and KBS are on the shelves here. I've used the POR15 tank sealer a couple of times.
    For some reason, postage costs US to Au has gone nuts in recent years.
     
  28. Pats55
    Joined: Apr 29, 2013
    Posts: 523

    Pats55
    Member
    from NJ

    In 1988, when I was selling a popular rust product. I was at a show and had my displays out as usual, and noticed that the silver always had a green tint. A man walked up to my stand, we talked for a moment, and he mentioned to me that this coating I was selling was similar to a primer that Mobay had developed. He claimed the Mobay material had little or no sunlight sensitivity and it would do an incredible 8000 hours salt spray. He was the owner of a paint factory in New York State and he attempted this formulation, but on the way home the can burst in the trunk of his car. After that, understandably, he shied away from it. I started asking a lot of questions, but he advised me just call Mobay chemical’s tech department with my questions. You can bet Monday morning I was on the phone with Mobay, where I spoke to an elderly gentleman. Every time I mentioned the black he got a little huffy—his exact words to me were, “It’s silver, like it or lump it.” I asked him where I could get a can of this silver and he told me to call Steelcoat in St. Louis, which I did, and they sent me a bunch of samples. The first thing I did was paint the front of the 38 Packard. It was stripped down to bare metal, and there was pitting on the top where the hood ornament went. Directions were to spray two coats, and I did exactly that. On the second coat the pitting disappeared...I couldn't believe it! Needless to say, I was happy as a little boy on Christmas.

    So that’s how I discovered a way to level pitting without having to use Nitro stain—and this is when our tag line “Get rid of the Pits” was born. In addition to that, we had an airtight seal so the rust couldn't come back, AND we could use any kind of paint over it. The reason for this is it’s solvent proof when it dries. So in my first experiment I discovered that it worked well on clean, steel, it sealed the rust airtight, didn't turn green in the sun, and dried nice and toothy for paint to adhere to it.And it sanded to a feather edge I started doing all kinds of experiments with body fillers and glazing putties, and have had great success for many years with these techniques I hope that you find this thread helpful


    [
     
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  29. alanp561
    Joined: Oct 1, 2017
    Posts: 1,867

    alanp561
    ALLIANCE MEMBER

    If you're not too picky about brands, I'll be glad to send you a couple of cartons of used Marlboro filters;)
     
  30. Elcohaulic
    Joined: Dec 27, 2017
    Posts: 2,472

    Elcohaulic
    Member

    I use spray grease on everything that you cant come in contact with. I used POR once. I drilled a hole into the POR treated steel and it pealed off like a candy wrapper, never again will I use that stuff. It is such a pain in the ass to apply. You have to use this treatment and that treatment and it peals off like cellophane..
    Another thing I didn't like was the fumes it gives off even a year later. Who knows what this stuff is giving off, its only been around for a few years..
     

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