The Stovebolt Site Forums The Shop Area Paint and Body Shop Painting Help

Hi guys, I have a question I hope someone can help me with and I need as much information as possible. I am finalizing all the replacement of metal, patch panels and the such on the cab and am getting ready to paint. Now, on the inside of the cab the majority of the cab looks like it has chicken pops, with these little surface rust spots all over. Now I am sanding these all smooth, as well as the remaining old paint that is very tough to remove. Now since the remaining paint is very firm with no cracks, I am thinking i am not going to take it all to bare metal, and when smoothed, I am going to treat the entire cab to a good wash and surface treatment using the POR 15 wash and metal ready, and then shoot the entire thing with primer. I am going to paint the interior with Dupli-color. Now Does this sound wrong, and should I use etching primer as a base coat, then regular primer and then top coat, or forget the etching primer and just primer, sand and color. Or should I spray some type of sealer primer, but not sure if dupilcolor makes one. I have some other questions on the esterior of the cab as well, but will get back to you guys on that.

Your question is pretty complicated but the basics dictate that your first order of business is to get a good, stable base to paint on. Do the best you can to remove any rust but unless you blast or dip you are still going to have rust in the pits. I would not recommend blasting because you will never get all of the grit out until you start painting and then you'll just wind up with it in your paint job. Dipping is ideal, but not always possible.

Sanding and then neutralizing the rust with POR 15 or Eastwood's Rust Converter and then following with a compatible primer should get you a base that you can paint over.

Unless I'm mistaken (things have changed a lot in the last 30 years) etch primer is for use over bare steel so not recommended.

I hope this helps.

thanks for the help, Yes I agree it is not practical to blast the entire inner cab, and don't wish to dip. I am currently sanding the entire cab smooth and am going to use the por 15 cleaner and metal ready to neutrilze the rust, coating the floor pans and foot wells with por 15, and am using OSPHO up under all the double walled areas that I won't be able to paint. Now do I just prime and go, or, as I saw on one of those darn restoration tv shows, do I need to paint one of those primer sealers, and then the regular primer coat and then top coat. Sorry for all the questions but seems the more I try and learn the more questions it brings.

According to the OSPHO website you can apply any primer over it so anything approved to go over POR 15 should suffice. But the greater question is why not just use OSPHO everywhere and forego all that POR 15 stuff?

You got a good point. I am going to use the por 15 for some work on the floor, for the remainder I am jsut going to OSPHO the heck out of it and then shoot over top of it all. I am also going to spray ospho throughout the underside of the double panels in the cab. Last question, can you recommend any type of leveling primer, or should I just go to the supply store and buy the entire system from primer to color? Appreaciate any advice.

just a quick question but what is OSPHO?

I will take a shot at this, but be forewarned that I am not a pro. I frequent a site called autobodystore.com in the forum section where a lot of pros do reply, so you may want to venture there.

First off, OSPHO is a brand name for a phosphoric acid product. Phosphoric acid converts rust to, I believe, iron phosphate. When you use phosphoric acid, you have to ensure that your primer doesn't also contain acid (i.e. etch primer and some hybrid epoxy primers)otherwise you risk delamination occurring. Normally, you use a squirt bottle, and mist on phosphoric acid, work it in with a scotch brite, then wipe it off with a paper towel. You should let it dry, then rescuff the metal with either a scotch brite or sandpaper before you prime. Phospo by itself only keeps rust from reforming if it remains dry. Therefore, you should plan to prime/paint any areas treated with it otherwise moisture will cause them to start rusting again.

On the primer, I wouldn't use etch for the reason above. I am using OSPHO, then epoxy primer. Epoxy is made to apply direct to metal and also to be used as a sealer before paint. The one I am using is Kirker Enduro (see smartshopper.com). It is very reasonably priced and after a few days is easily sanded without clogging sandpaper.

On the paint, I wouldn't recommend Duplicolor. I believe it is acrylic enamel which doesn't hold up very well. I would upgrade the paint to urethane in either a single stage or a base coat with a clear coat. The urethanes are a far superior finish.

I hope the above is helpful.
Regards,
Steve Lorio
New Orleans

Thanks to you as well, Now will the epoxy level out the pits and differing levels? and after the epoxy, do I apply the primer, black and then color? While on topic, for the double walls in the cab, should I try and spray some POR 15 or some other rust sealing paint as well as soaking the entire area with OSPHO or would that be overkill. I was thinking that I could drill some holes and use a wand of some type and then plug the holes with body plugs or seal with epoxy.

Dang it I meant after the primer block sand it out then paint.

Jim:
The Kirker Enduro I mentioned sands out pretty well. I am unsure how deep the pits are, but I would fill them with bondo, either before or after the epoxy if the epoxy alone is not enough to fill them. If you want to fill them after the epoxy, sand the epoxy first (80 or so grit) so the filler has some "tooth" to hold onto to.

Any areas that you use the Ospho on, should be at least primed afterward. The Ospho doesn't stop the rust if moisture gets to it. Therefore, something like the epoxy is necessary to seal it up from moisture afterward. Also, body shop supply places sell something called a cavity wax for applying to areas like you thinking of. You can look into that as well.

I hope this helps.
Regards,
Steve Lorio
New Orleans

If you apply epoxy primer over the bare metal, you don't need any Ospho. If you apply your high fill primer over the epoxy primer within a few days, you don't need to sand the epoxy.

Proper method would be: Sand to bare metal. Apply 2 coats of Epoxy Primer right on the bare metal. Use polyester filler to fill any small dents or imperfection on top of the epoxy primer. ( no need to sand back to bare metal for the filler) Within a week, apply 3 coats of High fill eurathane primer. Apply guide coat and block sand. Repeat with high fill primer if needed.
Always use a guide coat when block sanding. When you are sure that you are ready for your top coats reduce the Epoxy Primer as directed in P-Sheet and apply 2 coats. (This acts as a sealer). Then apply your top coats.

You will have a durable finish when done.

Frank

Well thanks for all the help, I think what i am going to do is to use the por on the floor pans, and then smooth the entire inner cab, apply OSPHO, though this product picklex looks promising but very expensive, they go with the epoxy to cover the bare metal and old paint. Then follow the steps Frank and the others have laid out. Probally take me a while as can't work on it as much as I would like but appreciate all the help and will eventually let you know how it all turns out