Surface prep for primer?

[FJsnoozer]

Have a little predicament. The painter and body man who was doing the work on my tub sides has not touched my truck in two months and stopped returning my calls.

While applying a skim filler coat and block sanding there were parts of the toprail and sides that were sanded back to bare metal. Now of course this has flash rusted due to out texas humidity.

Rust removal:
Do i sand with a DA and clean and prime?
Or should i use a chemical.

Priming:
I will have bare metal areas next to areas with evercoat rage. Once the metal has had the flash rust removed, can I spray 2k epoxy over everything and call it a day (move on to building primer and sanding for final paint). Do i need a different type of etching primer? I have heard not to spray etching primer over filler. Is this correct?

Thanks for your advice.
Here is the current state of the truck unfortunately. It was always supposed to be primed the same day that this body work was done, but it is what it is.

 

[1tontoy]

Prolly use a DA sander to remove the flash rust. And then you could wash with phosphoric acid.

Yes, you can spray 2K epoxy over everything (the filler and bare metal) at this point. For the final coat of 2K epoxy, you can add reducer and it becomes a sealer (extra corrosion resistance).

 

[FJsnoozer]

Thanks, I was reading a lot on the hotrod forum and jalopy journal and got a lot of input there.

They recommend SPI epoxy primer because it sands well. Some of them talked about using all epoxy and no 2k or hi build primer. They mentioned the limitation is that you need to let the epoxy cure completely before topcoating.

Am I on the right track?

 

[langsen]

If you use the SPI epoxy, don't use phosphoric acid to remove the rust. There are a bunch of posts about it on their forum.

 

[Splangy]

Prolly use a DA sander to remove the flash rust. And then you could wash with phosphoric acid.

Yes, you can spray 2K epoxy over everything (the filler and bare metal) at this point. For the final coat of 2K epoxy, you can add reducer and it becomes a sealer (extra corrosion resistance).

I would sand it down and shoot with epoxy. I would avoid any other chemicals because they may react with the existing body work. A sealer coat isn't going to add much corrosion resistance. It's really just applied to provide a uniform coat prior to paint.

Thanks, I was reading a lot on the hotrod forum and jalopy journal and got a lot of input there.



They recommend SPI epoxy primer because it sands well. Some of them talked about using all epoxy and no 2k or hi build primer. They mentioned the limitation is that you need to let the epoxy cure completely before topcoating.



Am I on the right track?

I haven't used SPI, but I can't imagine that blocking it is going to be easier or better than blocking a good quality 2k hi build/surfacer primer. Hi-builds are meant to be blocked and they sand easily. Epoxies are typically a PITA to sand, and clog up paper after every stroke.

 

[snobdds]

If I was in your shoes, I would do the following.

Take everything down to bare metal using a DA
Fill any low spots with filler and make surface smooth
Spray an epoxy primer on (I like PPG DP-90).


At this point you can do 1 of two things.

1. let the epoxy cure and put on a hi build primer and block sand to a smooth finish. Then put another coat of expoxy primer on and then top coat that.

or

2. Assuming your using PPG epoxy primer, let the primer flash for 2 hours then proceed to your topcoat. Epoxy primers only have a certain amount of time before you can't topcoat it anymore. I know PPG DP-90 there is a 7 day window where you must topcoat the primer.

I have found though, if your metal is straight, letting the epoxy primer flash for 2 hours then top coat directly after is the best for a DIY painter. Let's just say it's more forgiving then if you come back a day or two later. The reason being is simple, everthing is still set up, the gun is still at the same settings and it does not give time for dust to settle on the surface.

Good Luck

 

[Splangy]

If you're going to use epoxy on top of your hi build before topcoating, I would strongly recommend reducing it to a sealer. The last thing you want do do after all that blocking is add more texture before topcoating.

Also, I also like the PPG DP epoxy, but is expensive stuff so I would avoid it if you're an amateur. I would stick with the SPI or PPG's Omni brand epoxy.

 

[FJsnoozer]

Thanks guys! Keep the opinions coming. I will be DA sanding the flash rust and spraying epoxy primer.

I am undecided whether to go with SPI, or go with ppg and then top coat with the nason hi build that I already bought to get it more level. I am going to have to call around to check compatibility between these brands, or return the nason that I bought.

 

[Splangy]

Unless this is going to be a show car, I wouldn't spend the money on the PPG DP epoxies. If you are going to go with PPG, I would consider the Omni mp170 epoxy primer. It's good stuff at a fraction of the cost. I hear good things about the SPi, too.