POR15 & Powder Coat

[DanM]

Hey everyone,

 

I plan to use POR-15 to touch up the areas on my chassis where the powder coating has only partially covered.  As part of the prep process, are people removing the powder coat completely from the touch up area before doing the 3 stage POR process or are you leaving the powder coat in situ i.e. prepping and painting over it?

 

Thanks in advance.

 

[IamScotticus]

This is my plan as well, I have much more work to do than that!

Im no paint expert,  but my opinion about PC on a chassis or suspension that is prone to constant impact is that a coating which is easily spot repaired is better than any PC.  PC ia fine for outdoor furniture,  and perhaps the roll bar,  but for a chassis that is being chipped at, flexed and occasionally modified,  I would rather have removable and replaceable paint.

There's hard and soft drying paints.  Lotus used to use oven enamel.

The problem with PC is once its chipped and water gets in, it can continue to penetrate under the "shell" and spread.  If an area of PC is good and not a rock target, I think one could paint over it as long as it isn't compromised by a hole drilling or mod.  

Regardless,  Rustoleum Aircraft Remover is your friend.

 

Edited February 11, 2022 by IamScotticus

[DanM]

Hi @IamScotticus.  I reached out to POR-15 directly with my question and here is their response.  Hope you find it useful!

 

My Question:

 

"I have a powder coated chassis and there are areas where the powder coat layer is not very thick. Can I paint POR-15 Rust Preventative Coating over the powder coat? If so, what prep do I need to do?"

 

Their Response:

 

"Yes, you will have to lightly sand or scuff the area then use our Cleaner Degreaser before applying the POR-15."

[IamScotticus]

Thanks.

I wanted to add that the edges of the PC would need to be sanded down to a fine edge.  If the whole PC area is spotty, then just remove it.  PC, if applied well, should have an airtight bond with the surface but a rough edge can compromise that.

So many reasons why I think PC is overrated for chassis coating.  The only benefit is the production side.  PC produces an acceptable coating with less prep, labor and time.  In volume, cost.  But the end consumer doesn't always get the better deal.

Having said all that, yes PC can be done well if prep and application are done to a high standard with a zinc base layer, etc.  But the cost benefit is gone.

[Pokey]

I've got a stupid question so those reading please be kind, but how sure are we that the Caterham chassis are powder coated?  I ask because the durability of the surface and the thickness of the coating is more reminiscent of paint.  Even more so with the suspension components and the wing stays.

 

To be clear, this isn't a gripe as I don't really care either way.  What chipping that has occurred I've been touching up with an enamel and that seems to be working just fine.

Edited February 14, 2022 by Pokey

[IamScotticus]

I've always heard the mid-90s was a bad period for the powder coating. 

Im just trusting that.

Perhaps you are on to something?

[Christopher smith]

Just a chemist's perspective. I got involved just a bit in the 1990s powder coating formulations. For sure there are many varieties with widely different properties such as metal adhesion and elongation (flexibility). Not sure what frame manufacturers are using. When I had the bare frame of my 1959 series 1, I coated it with a 2 part room temperature cured epoxy paint. It has held up well albeit in pretty mild conditions ( never in rain or snow). Any chipping is easily touched up with abrasive paper then oil based primer and oil based top coat.