Painting my fibreglass boat.

[Anthony555079]

I desperately need some sound knowledge on re-spraying a fibreglass boat.
I have been told to sand the hull with 120 grit wet/dry then prime with 2k epoxy hi fill primer followed by sanding the primer with 320 grit by hand or 240 grit on machine before applying the final coat.
But then others tell me to use a wet/dry 600 to 800 grit before the final coat.
I have access to a spray booth but little knowledge with spraying boats.
First post, sorry if i'm not making sense.

 

[mickyryan]

personally I would not use a high fill primer as it shrinks in my past experience and all the beautiful work is flawed , also what you are looking to do , I would read up intensively because it is no easy task but I will give you my 2c.
1 light sand with 220 the entire thing
then make any repairs you need to make using gelcoat if its just dings and scratches
next step would be to prime the boat using what your paint supply recommends for the paint you are applying as to not cause any bad problems
next using a different color primer then the first primer, lightly mist and let dry, then go over it with a long board to reveal any highs and lows

once you are satisfied its the way ya want it use a sealer coat wet sand that with like 600
next apply your base coat if you are really good apply the next coat but usually you might have to wet sand the base coats after
that's done then apply the clear coat apply 4 or 5 thin coats of clear you might need or want to wet sand between those too. wet sand last coat wash dry inspect compound polish then apply wax
you should have a pretty awesome finish if you follow those basic steps but most folks don't because honestly its allot of work
most folk's will rough up existing finish fill what they want to fill then prime then paint then maybe wet sand after clear coats is it show quality? no but then that's up to the time you want to invest _ tack cloths are your friends after each any sanding and before applying paint.

 

[Anthony555079]

Thanks for your response.
I thought 320 grit was a bit much.

 

[gm280]

Anthony555079, :welcome: to iboats. Nice you could join us...

I have painted things before and my take is a little different. However, I will say this. The entire finish of your project is totally dependent on how well you do the prep work. If you are looking for a head turning finish, then you have to get your primer finish to that stage as well. Because regardless what anybody says, top coat paint and clear coats will never ever cover over scratches, dings and such. If you can feel a blemish or see one in the primer, it will stick out like a sore thumb. That IS a guarantee. If you would like to see how I refinished my project OB engine using a proven method, click on the engine rebuild link below or the trailer rebuild. I painted them from scratch. JMHO!

 

[DeepBlue2010]

I agree 100% with gm280, painting is 90% preping and the rest just follows. The grits of the sand papers are 100% dependent on the job at hand and the material you are using. Gelcoat is an extremely smooth finish. All you need to do is to rough it up so the primer has something to bit on. 120 or 150 will do. Wash and de-grease before and after and if you are using a power sander, don't go overboard. Let the sand paper do the job not your muscles. You don't want to take the gel off, only to rough it up.

From this point, just follow the instructions on the product you will be using. Sanding between coats or not, what grit, etc; all of this will be on the can.

Some 2 parts epoxy finish product such as Interlux Perfection are deadly when sprayed. No exaggeration, no BS, they will kill you. You need to be very careful with this. Access to spray booth is not enough, there is very specialized gear (full suit with air supply is the most important one) is a must and this gear is not cheap.

That is why most finishing top coats (including the one mentioned above) are formulated for roll & tip method. Done right, it can give you almost identical results to spraying.

 

[jbcurt00]

Many prefer to skip any clear coat on the hull, because it makes touchups more difficult.

An enamel hardener added to an oil based enamel paint can aid in drying, increase gloss and improve the paint's resistance to scratches.

 

[Corjen1]

Archbuilder's "miss morgan " build and Woodonglass's blue flamingo build have some very excellent info on paint... more recently Mark72/233 Thunderbird biuld has some really good info too.

 

[ondarvr]

Pick a brand and system of paint for your boat that's fits your budget and the quality desired, then follow the recommendations supplied for that line of product. The recommended methods can vary a great deal depending on the exact paint you decide to use, and it's important that you follow them.