Black_on_black

Hi

so my '86 Targa that I newly acquired is in a pretty good shape. Very little rust anywhere I can find (like none that shows anywhere obvious. It does have a lot of "hidden" areas, as you all know and in these, surprises can lurk. I would like to canvas treatment options through examples as I find them. Perhaps this has been dealt with a lot in the past, but methods and materials evolve and haven't seen any threads recently on this. If there is, please point me in the right direction and there would be little need to rehash something everyone on here knows, but I am a little bit of a newbie to old cars so hoping you have patience with me...

The only place actually currently where there is something that requires treatment is in the vicinity of the kidney bowls. My car is typically summertime driven, but there is some sand/stone buildup that I started cleaning out and no surprise some surface rust appears on the inside of the rocker panel as I get all the grit out. See pic below. I was considering just a minor sanding and painting over this with BRUNOX epoxy treatment, as a first step to limit and remove oxygen (so it does not wander) and then try and coat with stone guard. Or is there another treatment process?

The picture makes it look *really bad* but it looks like only very minor surface rust in reality.

/Mike

Igooz

The rust prevention material that has been around for a long time, and is highly regarded in the US are made by POR15. Take a look at their website and see what you think you will need. Surface preparation prior to whatever you seal with is critical.

Here is a link:
https://por15.com/collections/3-step...ventive-system

rstarga

I would hit that with a grinder to get to good metal then apply a good rust preventative paint then re undercoat. Looks like it has been done before so may be more than surface rust.

Black_on_black

Thanks for the tips

problem is getting in there, I can barely get there with sanding paper by hand and I get no pressure on it so very little effect. Tool tips? This is right next to the kidney, if you’re wondering where it is.

rstarga

A dremel or other rotary grinder should fit

ChrisHamilton

Sorry to be the contrarian but it is only highly regarded by folks who don't know any better. It's snake oil. It is a moisture cure urethane which is not actually waterproof. Your panel will continue rusting underneath it. No quality restoration shop would use it. I do restorations for a living and would never use it. I don't know of any high quality shop that does. It's been popularized by DIY guys who don't realize that your panel will continue to rust underneath it. You can't "Paint Over Rust" and expect it to last or be a real repair.

Couple of threads expanding on what I said above. (you don't have to be a member to view them)
http://www.spiuserforum.com/index.ph...ned-upon.2604/
http://www.spiuserforum.com/index.ph...-15-ever.4204/

Black_on_black

Really appreciate this guys, learned a lot through that POR15 thread you linked to @ChrisHamilton 👍🏻

let me see if I can reach it with the dremel, I’m thinking I need to extend the shaft somehow, but maybe it is small enough. It won’t reach the area in the small space between the bottom of the kidneybowl and the panel either way. I guess this area might be one of those where it is compromised and a yearly check up is required.

emac911

Get in there with a small media blaster then recoat with matching undercoat (Wurth)

Black_on_black

Whilst I was in there today trying to sand it, not getting a lot of progress, in order to review I stretched in with my phone and saw something not great…more “red” in an even more difficult place to reach. This is “around the corner” on the front wall ahead of the kidney bowl, I.e. the backside of the panel at the door opening.

this is one I won’t get to, so the media blast route is on the cards. Let’s see how that goes…

Igooz

Contrarian is OK and different opinions are important! I get it, there are many different approaches, angles, techniques, etc.

I agree that you cannot paint over rust, etc, and surface prep is important. Anyhow, I don't have a dog in this hunt and I have no association with POR.

But these guys have been around a long long time, and a lot of people actually use their products. Out of curiosity since you called the product "snake oil" I Googled the company, the parent P.O.R. has been around since 1923 in the US, and now they are a division of a large chemical conglomerate with well-known brands such STP, Rain-X, Adams Polishing, etc:

Brands - Recochem

What am I missing?

ChrisHamilton

The way it's marketed makes it "snake oil". The name makes it snake oil. They market it to "paint over rust". All it is is a moisture cure urethane. Meaing it cures in the presence of either atmospheric or surface moisture. That in itself makes it not ideal for coating bare metal. But it does allow it to "stick" over a rusty ill prepared surface. There are lots of moisture cure urethane's on the market. POR 15 markets it to automotive "restoration" or repair. Only difference between it and the other moisture cures out there.

Firstly, it is not waterproof. Then because it is so hard, the metal underneath it contracts and expands at a different rate than the POR, leading to it trapping moisture underneath(in between) the panel. Your panel will continue rusting underneath it. In the thread I linked to there are pics of what happens and what the metal will eventually look like. I can promise you this, no quality shop uses it. Only those who don't know any better.

If you want to paint your mailbox or lawnmower with it, no big deal. I would never use it on anything of value.

The proper modern way to attack a rust issue is first with proper preparation. Full removal of any surface rust via media blasting or wire brushing followed up with sanding with the appropriate grit, or using an acid product like Ospho, followed up with neutralizing the surface (very important or an epoxy won't adhere) then apply a quality 2 part epoxy primer.

Epoxy is a wonderful primer that when applied correctly is about the most bulletproof thing you can use to prevent corrosion. Not all of them are the same. I use SPI Epoxy (Southern Polyurethanes) which is one of the best ones made. It adheres extremely well and is flexible. I use it throughout the process of doing a body. By not using any urethane or polyester primer and only epoxy for build, the finished paint job is much more resistant to chipping because the epoxy remains flexible. I love the stuff.

500

I completely agree with everything Chris is saying, very good advice.

I have never used POR15 on a significant project, but I did try it once on something and the experience was very poor: In 2018 I was doing paintwork on my 2002 Subaru WRX, which has been a year-round daily car. The steel bumper beam (under the polyurethane external bumper cover) had some moderate corrosion. Instead of "doing it right" I thought I would try POR 15. I spent over an hour with a powered steel wire brush to remove most of the corrosion. Then cleaned and de-greased it and then liberally coated it in POR 15, both outside and in (went through a lot of trouble to get all the inner surfaces well coated. Then, in 2021 I had to do some body repair work on the car, and decided to comprehensively re-paint. Upon removing the bumper cover I was dismayed at how bad the bumper beam now was. It had seen more corrosion damagesince 2018 that what had accumulated from 2002 to 2018. Just as Chris said, the POR 15 trapped moisture under, and had separated from the surface and did a good job being a "cover" to hold moisture and accelerate corrosion.

I have done a lot of painting in my day and consider myself very thorough and even though it was just a bumper beam and POR 15, I put a lot of effort into it and the result was terrible and actually counterproductive.

So this time I had the bumper beam chemically dipped and I painted it with 2K epoxy and 2K top-coats and coated the inner areas with 3M cavity wax. I know from lots of experience that this will actually work.