Using original paint as base coat/primer, what's your experience?

[ching0n]

I think many of us here have done the strip/sandblast/etch primer route before spraying old HW. I'm sure many think that's the only proper way to do things.

In the past, I've used a different method when changing colors from original and/or recoating an old paint job that is well stuck to the base material. Typically it involves scuffing original paint (prep w/some abrasive per usual) and then wiping it all down w/paint thinner before spraying. The thinner gives the old paint a tackiness that in my experience helps the new coat stick better.

My logic is that some of these paint jobs use industrial processes (baking/electrostatic) and long banned paints have lasted decades and are difficult to reproduce w/an etch primer can. The work & cost savings is an added bonus.

Anyone have a similar method and/or tips when going this route?

 

[Farmer J.]

Yea, if the old paint is sound I rub it down, wipe it with 'Prep Clean 2800' and paint over it with Enamel.
Important to get rid of any bubbles in the old paint first. When painting have the surface warm and dry to avoid condensation.
Here's some good information, from the supplier I use:

The simple painting guide for coach enamel

The simple painting guide for coach enamel application- everything you need to know when brushing/rollering and spraying coach enamel

paintman.co.uk

 

[FrankLee]

The only(?) time I strip old paint is if the parts were previously repainted. Old repainted machines were usually done very poorly.

I always clean original painted parts with Grez-Off, rinse and towel/air dry. If there is light rust, I'll scrub it with steel wool. Heavier rusted parts get soaked in citric acid. Very heavy, crusty rust will get removed with electrolysis or a stripping disk.

When ready to prime, I mask and then wipe down with a rag soaked in acetone. I mostly use Rusty Metal Primer.

 

[bmwrd0]

Right now I am in the process of stripping of the shoddy repaint of a WWII era Montgomery Wards Lathe, which the paint was still decent underneath.