[tooski]

I'm doing a small patch panel. I've had the panel for about 6 months. I used POR 15 degreaser and Por 15 metal prep to keep the bare metal panel from rusting. Should I scuff/sand the panel now or just fill, prime and paint?

[mrennie]

Some epoxy primers explicitly state not to spray over metal that has been conditioned with metal prep or phosphoric acid as it can react with the corrosion inhibiting components in the primer and cause adhesion issues. SPI is one of them. I used to use RM epoxy that was approved over their metal prep so there is a lot of variation here.

[tooski]

Yes, I have read that. However, it does not answer the question.

[Entropy11]

It’s going to depend on what you’re putting over it. It will be outlined on their tech sheet. Like mrennie mentioned above, some products are ok with some sort of surface prep and some aren’t. No way to answer your question without knowing exactly what product you’re putting over it.

I only use SPI epoxy on my bare steel now and they outline what they want as far as metal prep before spraying. I use Ospho on almost everything and SPI outlines very specifically how they want the Ospho handled prior to epoxy. Once I neutralize it to their liking I can spray epoxy on my bare steel, do my filler work, then epoxy again and I’m ready to move on.

Only the tech sheet for your specific primer will have the correct answer for you. Whatever POR recommends means nothing.

[Cammer-6]

I trust POR15 products as far as I can throw it(in a 55gal drum)

[tooski]

[QUOTE=Entropy11;6488230

I only use SPI epoxy on my bare steel now and they outline what they want as far as metal prep before spraying. I use Ospho on almost everything and SPI outlines very specifically how they want the Ospho handled prior to epoxy. Once I neutralize it to their liking I can spray epoxy on my bare steel, do my filler work, then epoxy again and I’m ready to move on.

Only the tech sheet for your specific primer will have the correct answer for you.


Whatever POR recommends means nothing.[/QUOTE]


I then gather that the instructions on the jug of Ospho that I also have are not helpful.
I will consult with the primer producer.
Thanks, Frank.

[tooski]

Originally Posted by Cammer-6

I trust POR15 products as far as I can throw it(in a 55gal drum)

I have read various reviews on POR15. Some swear by it, some hate it. It is very difficult to ascertain its usefulness as I have never used any POR15 product previously. It seems I will have to find out the hard way.
Thanks.

[Entropy11]

Originally Posted by tooski

I then gather that the instructions on the jug of Ospho that I also have are not helpful.
I will consult with the primer producer.
Thanks, Frank.

That’s a prime example of the need to follow the tech sheet of the coating you’re applying.

Ospho clearly states you apply Ospho, leave it on, and then apply your coating directly over it.

A coating manufacturer (SPI in this example) states exactly how the Ospho must be treated prior to the application of their epoxy primer.

Whatever primer product you’re using should give you the only answer you need. If they don’t list the details of how to apply their product after an acid treatment I would contact them directly and ask them. It’s not worth dealing with possible adhesion problems down the road.