Stripping paint from a Sansui case

[Yggdrasill]

I want to repaint the sheet metal case of my Sansui AU-919. It has lots of scratches and surface rust. What is the best way to prep the surface? I have an orbital sander.

Do I need to remove all the rust?

Do I need to strip the paint completely or just scratch up the surface?

I have lots of experience painting wood, almost none painting metal.

Advice, please!

 

[fastbike]

You need to remove as much rust as possible. If you can't get it all off, use a primer that will chemically bind /inert the rust. After that the same as painting wood. Surface flaws will telegraph. Easiest way to avoid this is a textured surface such a Rustoleum Hammered tone.

 

[Yggdrasill]

Thanks, fastbike.

So if I am going to remove the rust physically (as opposed to a chemical rust remover such as Rustoleum), what is the best way to do that? Wire brush, sandpaper? What grit sandpaper does one usually use? Is it better to use an orbital sander or do it by hand?

If surface blemishes show through paint, how does one remove the old paint without creating such blemishes?

 

[Poultrygeist]

Know anyone with a sandblaster?

 

[62sunbeam]

Orbital with 80 to strip and then 220 to smooth then prime with etching primer from an auto parts store and then a few coats of black bumper paint.

Good luck

Eric

 

[tomlinmgt]

I own a powder coating business and we charge around $25 to grit-blast down to virgin substrate (white clean) and coat in any single stage color of your choice. I just Googled "powder coating Seattle" and several shops came up which means pricing in the area is competitive. If you want something that will outlast you (if the process is done correctly), probably not cost you much more than all the supplies to DIY and give you a scratch and chip resistant finish that's an order of magnitude better than any wet spray paint process can achieve then get it powder coated. It's usually a lot more affordable than people think.

- Michael

 

[Poultrygeist]

Had some rusty wheels blasted and powder coated - they'll probably outlast me.

 

[avionic]

Beadblast and powdercoat...

 

[tomlinmgt]

Keep in mind the problem with trying to "sand" the rust away is that corrosion eats into the metal and forms pits. If you're sanding you'll have to remove a substantial amount of good metal to get to the bottom of the pits. Grit-blasting with an abrasive etching media (sand, aluminum oxide, garnet, etc.) will remove the corrosion down in the pits of the metal without harming the good metal and leave an anchor pattern that provides a good "tooth" for the coating to bite into (glass bead does not do this...it peens, or closes the pores, of the metal). Though rust conversion coatings/treatments can do a pretty good job, nothing beats actually removing all traces of rust and applying coating over bare, virgin substrate with the proper profile for a coating to bond to. There are paint products that approach the strength of powder coating, but you'll spend as much for a pint of the product as you would if you just took the top cover and had it professionally powder coated.