Cowl Repaint Prep

[yorab]

I've got a 1961 Evinrude fiberglass cowl that I'd like to repaint. I've removed all decals and such and cleaned it up well. The original paint is still there except for a few spots where there is bare fiberglass is showing through. If the original paint lasted for 50 years then I assume that it has good cohesion to the underlying fiberglass. I'm assuming that it would make a good primer for the new paint. However, there are fine cracks in the paint. How should I go about prepping for the new paint? Should I completely remove the old paint? Should I fill the cracks with some kind of filler primer then hit it with the new paint? Should I simply rough up the old paint a bit and apply the new paint without primer? Perhaps another route? Thanks.

 

[JimS123]

Re: Cowl Repaint Prep

If you have spider cracks or mudcracks you have a problem, regardless whether the bond is good. The cracks will show thru the new paint.

Completely strip the old paint, sand lightly and prime with a primer intended for plastic. Krylon makes a good product. Then topcpoat with your coating of choice. Bonding to fiberglass cowls is not particularly difficult.

 

[5150abf]

Re: Cowl Repaint Prep

Alot of newbie painters think you have to remove all the old paint and you don't, just scuff it up good, sand a bit more in the areas where there are cracks, once it is all sanded prime it and see what comes through and sand that, re prime until all the imperfections are gone.

Start with 320 and finish with 400-600 grit.

Use a block when sanding so everything stays nice and flat otherwise it will be wavey if you do it with just your hand.

It takes some time and work but you really do get out what you put in, on a car the difference between a $400 job and a $10,000 job is about 100 hours, every thing else is the same.

I redid my engine with spray bombs from Autozone and it came out really nice, stripped mine all the way down though, alot of my paint was flaking off, probably had 40 hours in the entire thing start to finish for the entire engine and lower.

Don't get in a hurry and it will look really nice.

 

[JimS123]

Re: Cowl Repaint Prep

Alot of newbie painters think you have to remove all the old paint and you don't, just scuff it up good, sand a bit more in the areas where there are cracks, once it is all sanded prime it and see what comes through and sand that, re prime until all the imperfections are gone.

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Absolutely! Solid, well bonded paint does not need to be removed. Just need a light sanding to enable a good bond with the new paint.

However,.....wide spread craze cracking indicates a whole different situation. Mud-cracking will undoubtedly show thru no matter how well you sand it. If it is because it was repainted years before, it could signify a basic prep problem.

Stripping a cowl is a piece of cake. I can do it in a half hour, and new primer is a no brainer.

Just to be safe, maybe you should post some close-up pics of what it looks like.

 

[boater1234]

Re: Cowl Repaint Prep

I got some stuff at advanced auto parts made from duplicolor,it's a clear primer that is called adhesion promoter and is made strickly for plastic,fiberglass.The guy who works at the auto parts store paints boats to and he said he uses that for all the cowls he paints wit perfect results.He uses 2 light coats of that,puts a few coats of paint and then a clear coat if you want.Also i would assume you are putting new decals so you could clear coat them also.I didn't clear coat mine and it came out beautiful,Jim has helped me a ton and he knows what he's talkling about as others do here.Good luck.

 

[yorab]

Re: Cowl Repaint Prep

I believe that the paint is original. Those cracks are the general all-over type of cracks that I've seen with other fiberglass. Are those called spidercracks as JimS123 pointed out? If I'm understanding correctly, there are two schools of thought here: either remove the old paint completely or keep the old paint but use some kind of a filler primer to fill in those cracks. Obviously keeping the old paint means one less step. I'd prefer to do that. But, if those cracks are gonna come shining through, then I'd rather remove the old paint first. If I remove the old paint, what do I use to strip the paint that won't harm the fiberglass?

 

[JimS123]

Re: Cowl Repaint Prep

I've never used a "filler primer", so I can't comment on that. I've sanded and primed before and had it look perfect, only to have the cracks reappear two weeks later after finishing the topcoat. That's why I'm leery of recommending going over the top of a known problem.

Any paint remover will do the job. I use Zip Strip. It's the worst toxic stuff and you must do it with good ventilation. Of course, it works better than the low toxicity stuff. Paint it on, soak it for 15 minutes, then go at it with steel wool and a putty knife. I could clean a cowl in a half hour.

 

[5150abf]

Re: Cowl Repaint Prep

I think a hybrid approach here, like I said you definitely have to sand it pretty well and you want to remove most of the cracks then a high build primer and sand, after 2 coats and imperfections should be covered and you are ready to paint.

I would be leery of striping all the paint off, I would just sand it smooth, 2 coats of primer, sand between each then scuff the last primer coat and you are ready to paint.

 

[yorab]

Re: Cowl Repaint Prep

I may try that hybrid approach that 5150 recommends. If the cracks come through again, as has happened to JimS123, I can strip her down in the future and repaint. I've attached a few pics.

 

[viciousfishes]

Re: Cowl Repaint Prep

Im thinking about repainting my 68 johnson cowl. What is the best paint to use?