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A painting question....

3K views 29 replies 6 participants last post by  artbyjody 
#1 ·
I am at my girlfriends house browsing the web looking at different sailboat refit blogs and such. I just found 2 that contradicted each other when it came to painting the hull.

One of them just cleaned and lightly sanded the hull and the other sanded the heck out of it. I mean sanded down to nearly the fiberglass. It took him a very long time to sand the whole boat. He also sanded under the waterline very extensively.

So, do you really HAVE TO sand it very thoroughly or will just getting it smooth and roughing up the surface do well enough?

Tell me what you guys think and if you ahve tried it both ways or know of someone who has.
 
#4 ·
Are you strictly talking above the waterline?

Most sand the heck out of fiberglas and gelcoat when they get blisters and it is below the waterline. Then they fill and fair and prime and paint.

Above the waterline sanding enough to not remove the gelcoat but remove the oxidation and scratches and prep the surface for primer / eopxy. I painted my C-27, it was a light sand on the hull to apply the primer then paint (all above waterline). You really do not want or should go to the fiberglass if you have a gel coat present (above waterline).
 
#5 ·
If it's original gelcoat then simply sanding lightly and filling any nicks is all you need prior to applying the primer. If the boat is already painted, then you have the hassle of determining, as Jason said above, how well it's on there, and as/more importantly will there be a compatability problem with the coating you're planning to use. This can require doing a small test area and let it sit to see if the new paint attacks the old.

If the boat is faded and chalky looking chances are it is original gelcoat, but that's not a guarantee. The safest course of action, esp on a larger boat or when you're using expensive paint, is to get right down to the original glass/gelcoat and start over from there.

Chemical removers will leave less work behind as far as filling and fairing goes - it's difficult to uniformly sand all the paint off and leave a fair surface.
 
#6 ·
Thanks jody, well I didnt clearify if I was talking about above or below the waterline. I wasnt specifically talking about one.

Here I will give my two instances one above and one below the water line.

Above: The old paint is there and I think there is still some gellcoat on it but not much(although Im not very qualified to judge). I am thinking I can just sand those parts then prime and paint. But, there are numerous chips in the paint also. They go through the layer of paint and that is all. I think I just need to figure out how to fill them. So, what is best to fill them with?

The bottom: This is a trailerable boat and the bottom is in excellent condition as far as blisters go. I think just a decent sanding will do for the bottom.

What do you guys think about my mediocre plan?
 
#7 ·
Keep it simple. You can fill using the primer and adding a bit of silica to it to make it a paste - and fill in the spots that have the gouges and sand it after it dries. One doesn't haven't have to go extremes with it with expoxy / bondo fillers. You'll want to have at least two coats of primer and if you mix a ratio of 1/3 of the epoxy paint to primer - when doing the primer phase, it will reduce the number of coats to get a good solid color when aspplying the topcoats. I learned the hard way and for the red I painted my C-27 , it took nearly 6 coats to get a uniform glossy color.
 
#8 ·
So, not only do I need primer and the final color paint but I also need some epoxy paint?

Im new to painting but I am learning.

Im guessing primer is just that, primer, nothign to get it confused with correct?
Then epoxy paint, does it come in color or is it just that, epoxy paint?
Then the final coats, what kind of paint would that be?
 
#9 ·
Anything that is going to hold up in dirrect sun will be a two part paint SYSTEM i dont know if epxoy is the correct word BUT they all have part A part B and a thinner


The agressive nature of the solvents in the paint requires useing the correct primer or it will LIFT and ruin the job


Even doing the final coat of paint can cause problems if you dont follow the recoating times
 
#10 ·
The steps you take to do the paint job depend on what color you paint it, and how picky you are about the look when you're done. If you are painting a dark color, you need to be very particular about the prep work. If you're painting white, you can get away with a few imperfections.

The prep work that you do for the topsides (above the waterline, but not the deck) is different from the prep work that you'll do for the bottom. If you're sure that that topsides have been painted before, you need to either remove it all, or properly identify the paint. Some of the less expensive paints will go over just about anything, but epoxy paint (and epoxy primer) will eat cheaper paint. I recommend epoxy paint such as Interlux perfection. I used it on my boat, and after 2 years of hitting the dock (I rarely use fenders) and getting hit once while racing, I don't have a single scratch.

Once you have either identified the old paint or decided to remove it, you need to pick out your paint. Once you know what kind of paint you're using and what color, you know how much prep work is ahead.

You need to fill any deep scratches or gouges, and may have to grind out any cracks. For filler, I used epoxy with phonelic microballoons for filler. I found that this mix will sand about like gelcoat and doesn't shrink later.

Then comes the primer. Always use the primer that matches the paint. If you use enamel primer, then put epoxy paint over it, plan on stripping the boat and starting over. The primer will act as a filler for minor imperfections. When I say minor, I mean really minor. Don't expect primer to fill deep scratches. After you prime, you have to sand. When I got done sanding each coat, the boat had a bit of a shine to it. Kind of like a lightly oxidized gelcoat. I primed and sanded 4 times until I couldn't find the imperfections that I knew were there.

Now paint. Since I painted a dark color, it took 5 coats of paint before I was happy. I followed the instructions on the paint can, except the last 2 coats I thinned slightly more than recommended to get it to flow out a little better. It also made it really easy to run, so be careful if you do this. Between coats I wet sanded with 600 grit paper.

In all it was a huge amount of work, but I think it turned out well. BTW as soon as I saw this pic, I jumped in and scrubbed the bottom.
 
#11 ·
Use Awlgrip. They have a formulation that's made for rolling and tipping (I'll expand on this technique if you need me to). Forget about marine enamels and 1 part LPU paints (like Brightsides). They'll look great at first, but they fade very, very fast. There's no reason to worry about to part paints - if you can make pancakes for breakfast, you can mix the paint. As Tommays just mentioned, use the primers and solvents that are part of the system: this is VERY important.

If you are painting a previously painted surface, there are some techniques you can use to test for compatibility and adhesion of the existing paint.

First, take the reducer solvent and soak a rag in it. Brace it against the old finish and leave it for a few hours. If it softens the old paint, then the paints aren't compatible and you'll have to remove the old finish.

To test for adhesion, take a box opener and score a crosshatch pattern, making about a dozen 1/2" squares - go all the way through the old finish. Then, tape a piece of duct tape over the scored area and press it down securely. Leave it overnight. Remove the tape the next morning; if any of the squares come off, you have an adhesion problem and you'll have to remove all of the old finish.
 
#12 ·
Ok thank you guys for the GREAT replies!

I plan on painting the boat white, and it seems that is the easiest, good. I plan on painting the whole thing one color, the deck, hull, and under the waterline with a blue strip running the length of the hull. Will I have trouble finding the two systems (one for the above the water line and one below) in the same color?

NOLA, I think I may know what you are talking about when you say rolling and tipping. Is that where you roll on the paint with a roller and then come back over it with a brush? If so I know a little bit about it but not much.

I will use a part paint and both primer and paint will be from the same "system". I guess I could ask a WM or Boaters World or wherever I buy my paint at and they will know what I am talking about?

Then testing for compatibility:

First, what is a reducer solvent, does come in the "system" ?

On the adhesion test, do I need to apply reducer solvent first or just do it on the plain old paint?

Also, do I need to do the test on but the hull topsides and under the waterline?
 
#13 ·
Roll and tip is a method of applying paint without spraying it. It sounds like you know a little bit about it. Many of these paints are really meant to sprayed but equipment cost and (if you don't have the proper equipment, like a supplied air respirator) significant health risk mean some people, including me, seek alternatives.

To roll and tip, you'll roll out about a 6 ft. square section and with a very high quality - ie badger hair - brush, you'll lightly run the brush through the rolled paint. The brush is dry - do not dip it into any paint.

Reducer is indeed part of the system. These paints come with the topcoat and the converter, which are mixed together in a prescribed ration, and the reducer. The topcoat and the converter activate the paint. The reducer thins it so you get proper flow. You're looking for enough reducer to level out the brush marks in a minute or two, but not so much the paint runs. There is a little bit of an art to this.

Experiment first on a piece of scrap. If you feel your brush dragging or it's leaving marks, add reducer. If you're getting runs, wait a bit so some of the reducer can evaporate. The fact that it evaporates means you're dealing with a moving target. You'll need to continue to add a bit as you work your way around the boat. Also, forget about the recommended amount of solvent. In my experience, you need way more than the recommended max. Of course, I'm in southeast Louisiana. Sometimes it's just a little hot and humid here.

Another tip - don't roll and tip the primer. That stuff never levels. Just roll it on and sand it smooth.

I order paints from Jamestown Distributors.
 
#14 ·
On the adhesion test, do I need to apply reducer solvent first or just do it on the plain old paint
The plain old paint is fine.

Also, do I need to do the test on but the hull topsides and under the waterline?
My posts here have referred to the topsides. Bottom paint is a somewhat different animal, though in many ways simpler if you're not applying a racing bottom. Do you know what kind of bottom paint you have on now?
 
#15 ·
Thanks NOLA for you help.

When you explained roll and tip you said first roll a 6' square section with a high quality brush. I dont mean to get technical but do you mean with a high quality roller? When I lightly run the brush through the rolled paint the brush is dry, do I need to wipe it out after every 6' square section to keep it "dry"?


I know we are talking about a system here but does that system come as a package or do I need to know exactly what to buy to make my own custon system?

I just walked outside real quick and got out the orbital sander and some 120 grit paper. I sanded for about 5 min on some of the more scratched parts of the hull. The sander went though the paint rather quickly and then through what I am guessing was a primer then down to a yellowish color which I think may be the bare hull. I also sanded under the water line a bit and most of it is already the yellowish color which I still believe is the bare hull. There is a small amount of what looks to be old bottom paint in some spots but it comes off with ease.

I dont think it would be to much trouble to sand the whole boat though. I may not go completely though all of the hull topside paint with the sander but just smoothe it out(after I do the tests). If that yellowish color is the bare hull then bottom will be very easy to sand and it is good condition.
 
#16 ·
#17 ·
Well, you want a high quality roller and a high quality brush. Bes ure you get a roller with a short nap that can handle a urethane paint. Also, you do not need to wipe the brush, just don't dip it into the paint tray.

You'll need to know exactly what to buy. Ask for help and let them know you're rolling and tipping.

That yellow is probably original gelcoat. If the paint is coming off that easily, just go ahead and remove it all.
 
#18 ·
The paint will come with the base and the catalyst. You will need to buy the appropriate thinners and reducers. You will also need to buy the correct solvents for the prep work so there isn't a chemical compatibility problem with the surface before you paint.

When I painted my boat, I chose the paint then worked backward through the process until I knew where to start. I used Interlux's web site and tech support line to find out what solvents to use, what order to use them in, and what grit sandpaper to use. yachtpaint.com - the website of International and Interlux paints

With that paint job, and going back to white, I think I would strip it and start over. The biggest problem is going to be coverage. White over a dark color is going to be tough.
 
#19 ·
A standard BARE glass hull will NOT really have a color :D not yellow anyway in the thinner areas it will allow light to show through



You really dont want to sand to much below the waterline unless your going to build it up again with a barrier coat
 
#20 ·
About rollers and brushes. You'll want to use a very high quality foam roller. Redtree makes a good one. The foam is VERY thin, and leaves a pretty smooth finish. Then for tipping, I tried the badger hair and china brushes. I didn't like the finish, and they sucked to clean. At the local arts and crafts store (Hobby Lobby) I found a set of 3 very fine bristle nylon brushes in the artist brush section, for 3 dollars. I used the widest brush in the set (3 inches) and threw the other 2 brushes in the trash. I bought a brush set for each coat so I didn't have to clean brushes, and I didn't have to worry about not getting a good tip job from a sticky brush. Besides, the solvent to clean them cost more than the brush.
 
#23 ·
Yes, the gelcoat is the layer sprayed into the mold first, then the boat's structural fiberglass is built inside that, then bulkheads are tabbed in. This way a finished, shiny hull pops out of the mold.
 
#24 ·
Ok, thank you for that simple explanation.

I just finished sanding for the night and sanded for a total 2 hours and I think I got a pretty good bit done, nearly half of the boat.


This is how much I had finished in one hour.


This is the last picture I took at an hour and half. I worked probably 20 more minutes and got nearly the whole side completed.

I didnt go all the way up or down because I havent take the pin striping off yet, I plan on getting a heat gun tomorrow and removing them.

I did all this with 120 grit sand paper on a orbital sander. I think maybe I should have been using 100 or even 80 grit. I need to get some more tomorrow anyway so what should I get?

By the looks of it that IS the gelcoat which is perfectly fine to paint on correct?
 
#26 ·
Using 100 or even 80 grit for the initial part of this is fine.. things will go faster. Be careful that you use the sander flat and avoid the temptation to use an edge or a corner of the sander to speed things up. You'll end up with highs and lows that will require extensive fairing to look good later.

We've been down this road, and based on our sanding experience (effort, cost etc) I'd be sorely tempted to look at chemical means of removal to avoid that risk and extra work.

Make sure you use the recommended primer - it provides the bond for the topcoat, and do a good job of getting rid of the sanding dust and residue before trying to apply any coatings. A last minute solvent wash (we used a product called "Tumbler") - nasty stuff so be sure to use a proper respirator.
 
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