T Wash Substitute

[Onoff]

I want to paint some galvanised unistrut with Lidl Baufix black metal paint.

I do have some 2K etch primer and activator.

I don't have any mordant / T wash. Could I maybe use phosphoric acid? I have 24 & 48% solutions.

I've also got some of this, as it's "zinc" I wonder if that'd do as a primer that would stick to the galv?

Ta.

 

[Jackimus]

Seems to me that it would stick fine.

Using it as a primer, my thought is that cold galv sprays/zinc rich sprays can dry quite chalky? But that Baufix isn't particularly decorative stuff so I don't think it would matter, if it doesn't matter to you!

 

[Kram]

Black metal paint, I would think will go direct to metal without any additional primer. Degrease or a light sand first.