spi epoxy primer over paint?

R

ross52

Hi all,

I have a question that I would like to get opinions on. First, I'd like to say that I go out of my way to do everything I do, to the very best of my abilities. So, here's my question. I've stripped the engine compartment of a 68 mustang down to bare metal with a combination of selective sandblasting, paint stripper and acid. Everything is clean and ready for epoxy primer except a small area (shock tower floor) inside the shock towers. Water collects on the sock tower floors and rusts them pretty good. The good thing is the shock towers on mustangs are made of heavy gauge steal. I've removed as much rust on the shock tower floors as I care to and am left with very stable rust on solid metal. To remove anymore rust would weaken the shock tower and be counterproductive in my opinion. What I planned to do at this point is use rust converter on the rust that's left on shock tower floors and then go over that with spi epoxy primer. But, I quickly realized that Barry forbids using rust converter under spi epoxy primer. What I'm going to do now is use Rust-Oleum rusty metal primer inplace of the rust converter and after it fully cures go over it with spi epoxy primer. Tell me what you?

thanks

ross
 
Don,

I would have done that, except as I mentioned I didn't remove 100% of the rust, just the loose stuff and left the stable solid rust, which can be coated with rust inhibiting primer. You cannot apply epoxy primer over rust.

ross
 
Your best option is to blast it off or possibly try Ospho to neutralize what you have left. There are a specific set of steps to use with Ospho and you must follow them. Using Ospho properly to neutralize and stop the rust and then epoxy would be a much better option, it's still not fool proof, but much better than any other snake oil.

A good thread to read : http://www.spiuserforum.com/index.php?threads/issue-with-milscale-will-spi-epoxy-stick.7530/

Use the search function in the top right corner and search for a huge amount of previous info on Ospho
 
Don,

I would have done that, except as I mentioned I didn't remove 100% of the rust, just the loose stuff and left the stable solid rust, which can be coated with rust inhibiting primer. You cannot apply epoxy primer over rust.

ross
pretty much think what he means is the rustoleum rust inhibiting primer is going to come off that area faster than SPI epoxy will come off the rusted areas.

Ospho is fine on surface rust, cratered panels, but not really the mass that the shock tower is looking for. There are some heavy jelly rust converters that do not even need paint that might be a better option, just keep reapplying every few years
 
Tough rust has to be blasted off. Removing rust by blasting won't weaken anything. It may reveal that repair work is necessary, though.

If you aren't going to remove the rust, don't use SPI epoxy at all. Just stick with the system you start with. If you put Rustoleum down as your foundation, build on it with Rustoleum products.

SPI epoxy is not suitable for use over Rustoleum.
 
What I was trying to say is if you are intent on not removing the rust then epoxy will perform as well as rustoleum, if not better. Will it be good as blasting and removing all the rust, no it will not. But as thick as that metal is it will probably outlast you, assuming you can sleep nights...

To be honest I am surprised you are not going to spend another ten minutes blasting that area but maybe you just don’t want to deal with the media going everywhere.

Don
 
Here’s how I deal with Mustang strut tower rust. LOL....

Don

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"I have a question that I would like to get opinions on. First, I'd like to say that I go out of my way to do everything I do, to the very best of my abilities. So, here's my question. I've stripped the engine compartment of a 68 mustang down to bare metal with a combination of selective sandblasting, paint stripper and acid. Everything is clean and ready for epoxy primer except a small area (shock tower floor) inside the shock towers. Water collects on the sock tower floors and rusts them pretty good. The good thing is the shock towers on mustangs are made of heavy gauge steal. I've removed as much rust on the shock tower floors as I care to and am left with very stable rust on solid metal. To remove anymore rust would weaken the shock tower and be counterproductive in my opinion. What I planned to do at this point is use rust converter on the rust that's left on shock tower floors and then go over that with spi epoxy primer. But, I quickly realized that Barry forbids using rust converter under spi epoxy primer. What I'm going to do now is use Rust-Oleum rusty metal primer inplace of the rust converter and after it fully cures go over it with spi epoxy primer. Tell me what you?

thanks

ross"

Thanks to all for your advice and comments. I agree that the Rust-Oleum is not the best idea so I'm going to carefully sandblast the area to remove all rust and then epoxy prime it. The area in question is the lower back side of the shock towers. Most of the area I will be able to spray. But there's a connecting area where the spray will not reach and I'll have to brush the epoxy on. What area should I do first?

Regards Ross.
 
"I have a question that I would like to get opinions on. First, I'd like to say that I go out of my way to do everything I do, to the very best of my abilities. So, here's my question. I've stripped the engine compartment of a 68 mustang down to bare metal with a combination of selective sandblasting, paint stripper and acid. Everything is clean and ready for epoxy primer except a small area (shock tower floor) inside the shock towers. Water collects on the sock tower floors and rusts them pretty good. The good thing is the shock towers on mustangs are made of heavy gauge steal. I've removed as much rust on the shock tower floors as I care to and am left with very stable rust on solid metal. To remove anymore rust would weaken the shock tower and be counterproductive in my opinion. What I planned to do at this point is use rust converter on the rust that's left on shock tower floors and then go over that with spi epoxy primer. But, I quickly realized that Barry forbids using rust converter under spi epoxy primer. What I'm going to do now is use Rust-Oleum rusty metal primer inplace of the rust converter and after it fully cures go over it with spi epoxy primer. Tell me what you?

thanks

ross"

Thanks to all for your advice and comments. I agree that the Rust-Oleum is not the best idea so I'm going to carefully sandblast the area to remove all rust and then epoxy prime it. The area in question is the lower back side of the shock towers. Most of the area I will be able to spray. But there's a connecting area where the spray will not reach and I'll have to brush the epoxy on. What area should I do first?

Regards Ross.
I doubt it makes much difference.

Don
 
I'd spray a coat, then brush where the spray won't go, then repeat as necessary. In other words, do the spraying and brushing at the same time if possible.
 
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