Por15 paint issue - shying away from areas.

[dhutch]

Having used it before I'm now having issues with it shying away from areas.

Whole lot has been washed down with panel wipe, slathered in with a brush to eat off years of grot. Key applied to clean metal area best I can with some sharp 80grit.
Then washed down with their own Marine Clean mixed as directed with very hot water, again worked well in with a brush, wiped with a cloth, washed off. Then it's been wet all over with their Metal Ready photospate wash for half an hour, and again rinsed and left to dry. With the latter appearing to give a good etch all over.

Painted it last night and some areas it's just refusing to stay put, huge areas, and fisheyes in other areas. Even some small parts that where washed over the sink.

See pictures. I'm at a loss as to how I could prep it better.

Daniel

[Mercury00]

Did you key it with a DA, or by hand?

[-Ad-]

I red on the mig-welding forum that this stuff doesn't want a perfectly good surface to adhere properly. Needs quite the roughness and some rust.

Epoxy Primer instead should work on a nicely abraded surface after some 80 grit sandpaper.

[jagnet]

Any chance the parts could have silicon contamination? That'd need some solvent based panel wipe to deal with it rather than water based degreaser and even then it can still be an issue.

[dhutch]

Key was by hand, very quickly done on the chassis, access is awful as it's inside the trans tunnel. Done well on the loose trim.

I understand it prefers rough surfaces, and if I had my time again I might well use another product, but at this stage I can't help the chassis not been rotten, and withe the metal ready it is supposed to be good to go! Once on its a nice hard wearing finish, and I can't be hassled with two pot paints for these small areas.

I did actually ring Frosts and ask if they had other things I could use, but they recommend continuing with the Por15 and chassis black.

[dhutch]

jagnet said:

Any chance the parts could have silicon contamination? That'd need some solvent based panel wipe to deal with it rather than water based degreaser and even then it can still be an issue.

I can't think of any reason why there would be silicon oils anywhere near it, polish or anything else. Although as it's not oil based paint I expect a mineral oil would have the same effect and before cleaning there was a lot of that sloshing around, and I think waxoyl.

The panels are sealed with rtv silicone sealant, which might be the root issue.

However the silicone was clearly applied after the original paint 30year ago, and the paint has now been scrapped off by me, I have tried not to disturb the silicone or smear it, and it has since been washed with panel wipe. The phosphate wash appeared to have no issues with shying away so I thought all was well. The loose trim has no reason to have any silicone anywhere near it.


Given we are where we are, what should I attach the offending areas will before going again with the Por15?

Thanks

[jagnet]

I would give it a couple more goes with the panel wipe. Something's causing a reaction and I know that silicon can be a real headache to remove completely if there is any on there.

[dhutch]

Ok. I'll hit the effected areas with panel wipe and go again with the second coat and see how that goes. Final coat of chassis black. Then it's getting a hit of Diniltrol 4941 at the end of the process anyway.

Then we can get back to putting the new engine is, which is the actual point of all of this!

Cheers

[DaveCWK]

FWIW my process when using POR15 & most similar paints is to go over the surface with a flap wheel/die grinder if a complex shape, spray down twice with brake cleaner, then paint. I've never bothered with any of the surface prep products or water based degreaser & it has always turned out ok.

[227bhp]

It looks very much like silicone contaminant. Sometimes only blasting it clean is the way to get it off, panel wipe is too mild and anything water based won't touch it.

[dhutch]

Yeah well, it's not getting blasted, so panel wipe is is..... And Dinitrol!

[227bhp]

and more rust!

[dhutch]

Well yes, everyone says it likes sticking to rust. Maybe in ten years time there will be some for it! Hopefully not.