Anyone here using OSPHO rust treatment?

[b5blue]

  I've been using it for years to remove rust on all kinds of parts. Doing an online search I found a Hotrodder's sight where they were debating it's use and how some had had bad results with epoxy primers over it. I can see where any product that "converts rust" could lead to issues if not carefully used and cleaned/prepped properly afterwards.
  I sent many hours stripping down my roof this week and treated it with OSPHO several times in the process and scrubbed it down well this morning. The plan is to basically keep scrubbing any film left of it until gone leaving only the black "burnt" treated rust and naked steel before applying Eastwood's Rust Encapsulator in several coats. The deeper pits will be sandblasted as will the edges of the drip rails and such prior to spraying.
  It took a lot of grinding to get the rust off and down to the point of only having a thin blotchy pattern of the blackened stain left, what's left seems hard and stable. There are areas I'll hit again but being it's the darn roof I'm welcoming anyone opinions of how far I need to go now, before shooting.
  I'm not using epoxy primer as it's not UV resistant and topcoat is a ways off.
   Here's a few shots of where I'm at....   

[THEGENERALEE]

POR products are good and they make a rust encapsulator to treat the really bad spots, however remember this you must use a self etching primer on bare metal before applying any other top coat ie (epxoy primer) epxoy is a water tight finish if you are worried about uv cover it up with a tarp or something. If you are gonna drive it exposed a while just recoat the epoxy with a urethane primer to help ward of the uv.I have used ospho alot actually and as long as you clean and wipe it down good you will not have a problem.

[b5blue]

Well I hit everything black with my 6" sander using 60 grit and scrubbed the crap out of everything using OSPHO and a green scrubbie and found it breaks up the blackened rust even more. By giving a wipe down with a clean shop towel right away, as I do a section (Not letting it dry.) I'm getting cleaner and cleaner results. This process is removing so much I'll only have the deepest pitting to sand blast. (Only a few spots of that.) I'm ordering some of Eastwood's "Prep" to wipe everything down really well (Again I'll use a scrubbie to clean deep and lots of clean shop towels) before going over it with a tack cloth. I'll put up more pics when I get farther along.

[b5blue]

I got more aggressive Scotch Brite type scrubbies by Norton, used some 80 grit sanding disks also while applying OSPHO. Then used my Campbell/Hausfeld sandblaster with aluminum oxide to blast out the pitting. I re-applied OSPHO and wiped it down well before any could dry leaving a very thin film to prevent flash rust and to etch the blasted areas.   

[b5blue]

  I let that dry well overnight and made sure the film of OSPHO was very thin scrubbing any areas that had streaks in the film. Wiping all of it down with lacquer thinner and drying it with new clean shop towels then allowing a few hours to dry, I used a quart of Rust Encapsulator full strength and rolled it on with a 1/4" nap roller working it into the metal well with 2 coats several hours apart. I did the edges and some of the deeper pitting with a fine haired brush to build up and fill the surface. From experimenting on my Cherokee I found the Encapsulator sands nicely and fills scratches and pitting well. This shot is from later the same day. Next I'll block sand everything even and smooth after a few days of letting it cure. (And then I can start checking for any adhesion issues.)   

[b5blue]

And one more

[b5blue]

  The Rust Encapsulator has been blocked with 150 grit. It sands quite nicely and really most was sanded off to fill and level surface pitting. Using the semi gloss sheen as a guide I block sanded everything to a flat surface and used my shop vac to remove sanded paint buildup as I worked to a uniform smooth flat area. I sprayed on more to cover the exposed steel and fill some deeper pitting. I found no adhesion problems in any areas including test spots I did here and there around the car experimenting with different ratios of it thinned down quite a bit. (over 20%) As we have had a ton of rain the car has gotten wet and had to sit wet yet no rust has returned. 
  This was the only very large surface of the car with wide spread surface rust to deal with, I'll keep a close eye on how it ages in the months to come. It seems to have worked well.
  I did learn, as seen at the midway pictures that the OSPHO's only going to penetrate so far. Further sanding of what looked black and stable revealed brown rust between the black and steel past a certain mil thickness. Removing all but the thinnest film of OSPHO before it can dry at all was also important as was rescuffing prior to painting.
  At this point I'm glad I chose Rust Encapsulator over Rust Bullet for its ease of sanding, I've read here Bullet is tough to sand as it's so hard when cured. (I'd have been screwed.)