Primer to allow 2 pack over 1 pack paint.

[Ceirwan]

I'm repainting the cockpit of my Sadler 25, and in the interest of longevity I'd quite like to use 2 part paint.
Unfortunately the PO only used single part. Its been sanded back ready for painting, and while I've made it back to the gelcoat in some places, overall there is still a lot of the old paint on.

As I can't use 2 part over 1 part, is there some kind of 'primer' I can use to allow me to use 2 part without sanding away all of the old paint?

 

[William_H]

Well AFAIK the correct primer for 2 pack polyurethane is a 2 pack primer. Which will have the same problems of tending to soften/dissolve the original 1 pack paint. Therefor the only option is to use a chemical paint stripper to get rid of all the old 1 pack. Caustic Soda is a cheaper stripper but be very careful it dissolves horse hair brushes and loves human skin. Or alternatively you might have to consider a one pack paint.
I find the floor of cockpit really challenging. The original non skid surface gets smoothed out by paint. While the pinacles of the non skid lose the paint quickly to give a dirty colour. Only option might be more paint and a sand type additive to the paint. Others have found paving paint good. good luck olewill

 

[Pasarell]

Of course you can't put 2 pack polyurethane over a 1 pack alkyd type paint as all the manufacturers will tell you. But in fact you usually can if the 1 pack is old and intact and especially after rubbing it down. No guarantee so it is worth testing an area first but if the 1 pack is a couple of years old and been well weathered then it will usually work. You will get the benefit of the appearance of the 2 pack and the extra hardness / abrasion resistance but you won't get the improved adhesion of a well applied 2 pack. You have to remember you are hanging it off the old 1 pack that is already there so if that fails you nice shiny 2 pack goes with it

 

[Ceirwan]

Thanks.
I heard somewhere about an 'intermediatary' primer of some kind. So you'd use that over the 1 part and then the 2 part primer over that.
The existing 1 part is very old, but very well adhered as constant sanding has failed to remove it in a lot of places!

Fortunately I don't have to do the non slip as that will be KiwiGrip. Its the cockpit thats proving the hardest!

 

[JVL]

Thanks.
I heard somewhere about an 'intermediatary' primer of some kind. So you'd use that over the 1 part and then the 2 part primer over that.
The existing 1 part is very old, but very well adhered as constant sanding has failed to remove it in a lot of places!

Fortunately I don't have to do the non slip as that will be KiwiGrip. Its the cockpit thats proving the hardest!

What your looking for is an Isolater paint , it's easier to spray than brush and tip but you can achieve good results just make sure your surface is "flat" and tacked clean before you start applying

John

 

[Richard10002]

Not for the OP, but I've just used some International deck paint, which is really thick, and applied by stippling, rather than brush strokes. Its dried quite rough, and seems to be quite slip resistant. Given that the non slip additive is part of the paint, I'm guessing the colour won't wear off.

 

[PCUK]

As said by JVL, an isolating primer. Interspray centres use use it to ensure no problems with previous coats. Not sure where you'll get it from though. Although car painters used two pack paints as a matter of course these days so you might find that they will be able to advise you.
I must admit you would be better off stripping back to the gelcoat and starting afresh with two-pack.