dumb paint prep question

[moonie5961]

removed

[tommays]

Well


The NEW paint has to be happy with the OLD paint OR it will fail

This will require some whats there and whats going ON

220 grit would be on the rough side in terms of showing

Fiberglass SAFE stripper would be a much better way of getting off the old unless you want to sand a really long time

[Captainmeme]

60 grit? Me thinks that is too aggressive. If the paint is well attached, not peeling off, I'd use around 220. Check to see what the manufacture recommends. I've seen a Hunter that had the hull paint coming off in sheets. The painter/owner thought that wet sanding before painting was the right thing to do. Pant needs bite.

[sailingfool]

You have to think what the sanded hull will look like after you put shiny new coat of paint on it. I would expect 200 to be too corse and show shwirl marks in the paint finish. Take a look at the sanding instructions for Awlgrip,
"Sanding & Sandpaper *"
while you probably don't need to be as fastidious as you are unlikely to use a paint with such a high gloss finish, if you follow their guidelines you minimize the risk to have to remove your first effort and start over...

[jarcher]

Originally Posted by moonie5961

I read somewhere that you can put a soft paint over a hard paint, but not the other way around. So, if the paint on my boat is a one part (soft) paint, then it won't be happy having a hard 2 part paint over it. Is this correct? If so, it looks like I'll have to remove it completely.

Its not that simple. See this chart:

http://www.yachtpaint.com/Images/15_20650.pdf

Of course if you don't have any idea what is on it, then that chart is not too helpful.

[paulk]

Have you read the label on the 2-part paint you're planning to use? If it calls for a primer coat, that should probably take care of the rough surface caused by your aggressive sandpaper. If it doesn't say to use a primer, you will probably need to re-sand in order to avoid swirl marks. The 2-part paints that I am familiar with are VERY thin, and show every surface imperfection.

[Capnblu]

I use 80 grit to sand for filler/epoxy, 220, for prime coats, 300-500 grit for paint finish, 1500- 2000 for polishing if applicable. I don't use above 500 grit for adhesion reasons. If you use a random orbit for your final sand before paint, you will probably be able to see swirls through the finish. Therefore, maybe it would be a good idea to wet sand your final primer coat before paint. A good trick when doing this is a spray bottle of warm water with a small amount of dish detergent, as you sand a section, use a rubber squeegee to dry off where you have sanded, you will see small imperfections easily, and if you take your time, and even out all the highs and lows, you will achieve the best result.

[oomfh]

If you haven't sanded through the gelcoat down to the fiberglass - why not lose the paint and restore the gelcoat to its original finish. As you are discovering, once you (or the DPO) paint over gelcoat you'll be chasing scratches the rest of the time you own the boat.

[bljones]

Stupid question, but are you talking about painting the topsides, or below the waterline? I ask because you mention "soft" and "hard'" paint.

Definitely step away from the 60 grit.

[scottyt]

another option to remove the paint is get it soda blasted. then you only need a light sanding to prep for the paint