Surface Rust

[BAMA_57]

I'm back working on my 500 and have sanded all the paint/primer off down to the bare metal. The car had several spots of surface rust and in sanding off the rust I still see "freckles" after sanding/grinding the rust. I plan on using 2K urethane primer over the entire car. My questions will this keep the rust from coming back? I've been told I need to get rid of everything.
Ron

[Wirenut]

I used a metal conditioner similar to Ospho to treat the metal after it was sanded as clean as I could get it. I was able to leave it as conditioned out of the weather until I was ready to prime, then I used a metal wash to wipe down all of the surface. I cannot recall the name of the conditioner but it was purchased at PPG paint store and was in a 1 gallon jug and is especially made for surface rust. I bought the metal conditioner and the metal wash together so I could treat and wash in a 2 step process for the parts I did not paint right away.. Hope this will help..

[RICH MUISE]

Your first coat of primer should be epoxy, followed by the 2k. The epoxy primer will do a better job of adhesion to the bare metal, and a better job of sealing it off. However, as wirenut said, you need to treat the bare metal first, particularly in your climate. I used por 15's metal ready. It's probably similar to what wirenut used. If I remember correctly, it's a zinc phosphate that etches the metal, treating the rust deep into the pores and scratches, crevases, etc. of the metal. Follow the instructions carefully, except just before your first primer coat, jitterbug the gray coating off down to shiney metal. regarless of what the manufacturers tell you, the coating will interfere with the epoxy primers bonding to the bare metal.
Why go thru the bother of coating the metal, then sanding it off? It will treat the rust, and it will leave the coating in the pits you were talking about, as well as scratches, etc.
I strongly recommend the epoxy first, but if you decide to go straight to the 2k, then make sure the product you pick is formulated for bare metal, not all of them are.

[Jeff Norwell]

Check out Gibbs.

[RICH MUISE]

LOL...In a hurry this morning Jeff?
who or what or where is "Gibbs"

Bama...I should add in reply to your question "will the 2k stop it from rusting?".Absolutly not...it'll rust right thru the primer....only sealers actually 'seal', which is why you should add a sealer coat on top of your last primer coat. It is done under your first paint coat at the time of final paint...sort of like your first layer of paint.. All primers, paints, and clearcoats are porous. That said, particularly in a humid area, nothing will stop rust completly, which is why you must be thorough in prepwork. The idea is to slow the rusting down as much as posible to a snails pace

[Jeff Norwell]

yea .very rushed this morning Rich.... ha ha ha. sorry
here.....
http://www.roadsters.com/gibbs/

I am sure a better google search will get even more results.... I have used it on bare metal and it works very well.

[BAMA_57]

Thanks guys. My main concern is keeping it from coming back. I did a little research and I think I'm good. The prep I'm using is the POR15 metal conditioner (ACID). It will stop the rust then I'll Prime and seal before painting.

[rmk57]

We used to use this stuff on our salt spreaders at work before we went to stainless. Works really well on industrial applications, not sure about automotive. May be worth a look.

https://www.google.ca/url?sa=t&rct=j&q=conquest%20rust%20converter&source=web&cd=1&ved=0CDcQFjAA&url=http%3A%2F%2Fwww.chemsearch.com%2FproductDetail.asp%3Fcountry%3DUSA%26language%3DEnglish%26language_id%3D4%26countryName%3DUnited%2BStates%26pName%3DConquest%253Csup%253E%253Csmall%253ETM%253C%2Fsmall%253E%253C%2Fsup%253E%250D%250A&ei=vL43UteaNMWJiwKo3YCYBQ&usg=AFQjCNH5_2ykSxoV6-twjS1xksjA6Rgv0g&bvm=bv.52164340,d.cGE

[BAMA_57]

You have to be careful of some of these "RUST CONVERTERS". They will not all take paint. I used some on another restoration project (on small brackets) and found that out the hard way. Vinegar and water will kill the rust and is cheap. But you have to seal it afterwards. That is the key.

[Limey57]

I'll second the caution on rust convertors, some form a dark blue/black layer after they have converted the rust and 2K paint just doesn't like it.  I had to strip a 1960 Impala back to bare metal TWICE after I used that stuff, I wasn't happy (fortunately it was only in primer).

Over here we've got several products that will remove rust completely leaving no residue and they're safe & water soluble as well.  Not sure if they're available in the US, but I used them on the rusted panels on the previously mentioned Impala the second time round and it really does leave the metal sand-blast clean:   http://www.bilthamber.com/deox-gel

Blasting is by far the most effective rust removal process but isn't suitable for large flat panels.  Whatever you do, avoid the "chemical dipping" processes, I had my Ranchero done and regretted it as it actually promotes rust in the seams & you have to drill out the spot welds, sand blast the rust & weld it back up again.  I'd sooner strip an Impala twice......

[RICH MUISE]

The por 15 "metal conditioner you are using I am assuming is "prep & Ready". It is the product I refered to as por-15 Metal Ready, which is it's old name. I don't know if they made any changes to it other than the name. Zinc phosphate acidic bath that leaves both a residue and a coating. The residue comes off pretty well with the water bath after treating. If you did it correctly, during the treatment, keeping it wet for 15 or so minutes, you will see the metal turn gray. That is the coating. The wash-off residue is yellow. I use a spray bottle and a skotchbrite pad during the treatment process just to work in the solution. Por 15 website still states, as they always have, this coating, and even the residue to some extent, aids the por-15 to adhere. They are absolutly correct up to that point, but then they go on to state, it helps with other topcoats or paints as well. This is where I strongly disagree. If you don't jitterbug or DA that gray coating off, the primer will not adhere correctly. I hate to keep reemphasizing that, but I'd hate for someone else to go thru what I did..similar to Limey's experience.

[BAMA_57]

Okay, finally got it back in primer. Treated with por 15, sanded, primed with epoxy, then 2k primer.

[RICH MUISE]

Way to go, Bama. That's the best way to go, imho.
Let that 2k primer sit for as long as you can before you start blocking, at least on the final coats. It gets harder as it ages, and therefore harder to sand, but you want to let it do all the drying and shrinking it's gonna do before that final block.
I'm assuming when you said "treated with por-15 and sanded", you were referring to the Zinc phosphate made by por-15 and not  their  paint-like product commonly referred to as "por-15".?

[BAMA_57]

Correct, I should have said "Metal Ready" by por 15.