Prep of levelling rust pitting on strut housings.

[Mikesmalaga72]

For those that have gone there and had good results. I`m looking at two options for either prepping for single stage urethane, or powder coat. For urethane bondo type filler for the rust pits, I believe the DP90 epoxy and top coat with urethane single stage paint. For powder coat, media blast, and use a (metal filler) for the rust pits then powder coat.

Question is, what is the best high temp metal filler that spreads on well etc used for powder coat that can withstand 400+ in the bake ovens and not shrink or pop?

 

Thanks   

Edited February 19, 2022 by Mikesmalaga72
correction

[TobyB]

I'm a huge fan of not putting anything on there that doesn't need to be there.

 

so let your pits shine brightly.  When it's not exterior panelwork, of course.

 

That said- rust's almost impossible to completely remove, so after any

mechanical means, I always use an etchant/rust prep/ etc.  The idea being

that the treatment removes any residual oxygen, so the inevitable rust is still

there, there's just no oxygen to let it continue rusting.

 

So add an etchant to the paint phase- usually, mechanical removal, surface prep,

acid etch or acid- bearing primer, then DP90, then filling, DP sealer (reduced DP)

again if needed for mechanical removal if you've sanded through to bare metal,

a sealer DP coat OVER the filler, and then top coating.

 

I don't know from powder coat.  When I looked into it decades ago, welding and

grinding and sanding was the only 'approved' method.  But that was a long time ago.

 

fwiw,

t

 

[Mikesmalaga72]

Thanks Toby..

[stephers]

Eastwood has a product that is called Metalab   It is a metal type putty that hardens and can be powder coated    I use it all the time on alum parts that are slightly corroded, put it on, let it cure, sand it down and then I powder coat them      Usually comes out smoother than the rest of the part   I am sure that it would work on your struts but they would have to be completely media blasted and the metal prepped properly with Metal wash or Ospho    

 

Thanks, Rick

[JsnPpp]

I agree with not hiding your pits. On top of obfuscating potential issues in the future it also is a bit of false advertising for future owners. Nothing wrong with a properly cleaned, de-rusted and prepped 50yo car part!

 

What works for me:

• Descale using chipping hammer or air-powered needle scaler
• Mechanical cleaning using sandpaper, flap wheel or stripping disk
• De-grease using solvent and/or water + dishwasher detergent
• Thoroughly dry (I often use a leaf blower and/or heat gun)
• Apply phosphoric acid to convert iron oxide to iron phosphate (I have had good luck with Ospho)
• Wash thoroughly with water (yes, water). Rust is black, shiny metal is etched
• Dry thoroughly! Leaf blower and/or heat gun and/or sunlight
• Primer/filler/primer/paint, etc.

I don't use high build stuff on anything not external facing. Like I mentioned, I want to see whats happening under that paint in case I didn't prep it well and also not hide history. Personal preference of course.

 

Jason