So im also working on some rust issues. Been researching the same thing. Havent decided on a product/process yet but, what ive found is people love POR15, however it appears to be a "sealant" that encapsulates the rust. Not a converter. My only concern is the possibility of the rust continuing to deteriorate and eventually cause the POR to fail/delaminate.
So, what i am probably going to do is first clean off all the rust i can, then convert it to an inert metal by using a rust converter like Ospho. After i have stopped the rust, or at least minimized its ability to grow I will then seal it with something like POR15.
I have read alot of people like Mastercoat permanent rust sealer as well. Only thing about this stuff is that its silver.
Thank you all for the replies. I'm in the process of pulling the front clip off of my 64 moredore. I found a rotted area just to the left of the upper skirt mount on the RS. I've been looking for a firewall in case I need to replace it. Either way I will want to paint the firewall with one of these products.
I used POR15 like 15ish years ago some on my Nova...then on an S10 project(I believe) .
The S10 is long gone but I'm finally back to working on my Nova and hope to have it in the road next spring/summer.
POR15 is tough..just a longer process..of cleaning degreasing ...etc..
If not applied properly it'll peel off.
I happened by some Rustoleum Rusty Metal Primer at Meijer one day for like $2.50 for a quart...ive spent the last 2ish months off and on slowly underneath my Nova wire brushing, using acetone/lacquer thinner then the Rusty Metal Primer..as a primer...then my custom mix of Rustoleum semi gloss and flat black paint..
I've brushed/sprayed some but I'm pretty happy with it..
The Rust-Oleum is cheap and it works ...I'm not doing a concourse restoration..it's a 74..but I do love stock looks.
I also have a running experiment going with the Rusty Metal Primer vs..rustolem rust reformer(spray can) on. A piece of Rusty scrap steel. https://www.instagram.com/p/B4sxijhgCx_AV8aNJhQMOdJFVlNhwelRfDvp8I0/?igshid=1vh8bhfhc10zr
That's a link to my Instagram...3months onward and it's doing pretty good I'd say..this is 100% outside behind my barn..I didn't do any prep to the steel beforehand..just straight painted it
For me it depends on the part type/size. Getting rid of the rust is preferable with me. Wire wheel till it's gone if you can get to it. For the sub-frame I used the KBS frame kit, worked great. Inside doors and the body I knocked down the rust to a light surface rust and covered with POR-15. POR-15 must have rust to bond and seal or it will fall off. I did not know you could paint over converters with it? If the part is small enough soak it. Evapo Rust works awesome, see picks below. Got a couple gallons of it in a tray and started soaking. 24 hrs. for the hood hinges then wash with water and paint normally. If you order Evapo Rust online for store pickup from O'Reilly it is $15 a gallon rather than the usual $25. It works.