Fish Oil Before Stoneguard - Unorthodox?

[Lukas]

Hey all,

 

I was recently talking to an ex-panel beater, now yacht painter, regarding my 240z and painting/rust-proofing the underside. Keeping in mind my limitations are far as spraying goes (in a garage, no good extraction, so acrlyic based), he suggested that I do the following for the underside of the car:

 

Etch Prime -> Prime -> Top Coat (Black in my case) -> fish oil -> stoneguard (Not specific on type, I was planning on using U-POL Raptor).

 

His reasoning was that the fish oil will actually spread into any cracks and crevices, sealing better than the paint would, but will still set hard enough for the stone guard to adhere properly for a prolonged period of time. He does brilliant work from what I've seen, and working on yachts he should know rust proofing well, so I don't have much reason to doubt him aside from never having heard anyone else mention this workflow in the past.

 

Anyone have any advice or thoughts?

 

Cheers,

Luke

[gav240z]

All I know about fish-oil is generally you want to apply it last, otherwise you can have major issues when painting. I'm not sure how compatible stone guard and fish oil are, so can't comment on that combo much.

[1600dave]

I've never used fish oil on an external surface (ie the underside of the car), only inside cavities - doors, sills, etc. I always put it on last, after I have sprayed anything that needed painting as it will always get somewhere you don't want it to..... As an aside, my favourite "secret mix" was equal parts fish oil and Tectyl rustproofing.

 

Personally, I'd skip the fishoil in your plan. Paint and stoneguard the underside, then pump the fish oil into any cavities / frame rails / anywhere moisture and dirt will collect. 

Edited March 1, 2016 by 1600dave

[Sirpent]

Dave is 100% correct, it is a final application not a primary one.

 

Fish oil under any type of substrate would be disasterous.

 

Cheers

 

John

[260DET]

My experience with fish oil is that once it 'dries' it's fine to put a similar solvent based stone guard type product over it. Problem is that it will take ages to get to the tacky stage where something compatible can be applied and stick to it. Forget putting a top coat over it though. Fish oil is good stuff, it gets right into the metal unlike stone guards so there is sense in what old mate suggested.

[Clockwork]

Yeah similar to Dave, my father in law does a lot of boat stuff and will always spray fish oil, but only inside/cavities etc.

 

If it still let's the stone guard adhere, can't hurt to do both

[gilltech]

I agree with your friend, oil first into every possible crevice, & allow a good week or more for it to set up, but clean off the excess oil trickling out wherever it's not wanted on a regular basis. Then apply the selected stone guard on to a thoroughly clean surface as it's so much thicker & is more likely to bridge crevices than soak into them. Different products doing quite different jobs.

[260DET]

Used some Export brand spray fish oil a couple of weeks ago, it has now dried sufficiently to easily take a coat of stone guard or similar tar type substance. So yes, old mate's suggestion is a good one, much better for an old car than just applying a coat of stone guard by itself.