Painting Boats

[LennieG]

Ok....not so quick. Rust-oleum website has one topside marine paint and it's description is oil based alkyd, not one part polyurethane. Paul, are they one in the same or have I lost something in the translation?

Thanks

[Alan Stewart]

I'll throw in my 2 cents. I painted my (previously kens) 17 with ppg amercoat 450H 2 part poly. As far as I can tell it's providing all the long life benefits of the expensive awlgrip 2 parts at a fraction of the cost (like $60 a gallon) you can get it at a Glidden paint Store. Look at ppg website for local distributors. You can also have it tinted.

it's a 5 to 1 mix ratio and it's a little thicker than awlgrip but to really improve it you can and should use awlgrip brushing reducer to thin it. If you don't mind wearing gloves and a respirator i wouldn't use anything but a 2 part poly.

[PAR]

You may be right Lennie, I haven't checked their MDS, but will (sometime, so don't hold your breath).

[LennieG]

Thanks all. Picking paints should be easier but my nature is that I get tripped on these kinds of detail. Good news is that I will eventually get it right usually. I may just bite the bullet and use two part, figuring if I can build a boat I can paint a boat with boat paint. I and others flipped the boat this week and today I am working on it for first time in 7 weeks. I CANT WAIT TO BE BACK AT IT.

[Mike Vacanti]

I've found that getting a good paint finish is the most difficult part of boat building. It's the only part of my boat build that I had to redo.

[LennieG]

Howard-

Can you tell me what the cross hatch test is? When I originally read this I assume you meant what Paul once explained about using long boarding and sanding two directions to identify low spots.....is that what you are referring to?

Thank you!

[Howard]

The cross hatch test is outlined in the System 3 Epoxy Manual. There is apparently a paint industry technical standard for it, but the crib notes version is you create a tic-tac-toe type grid on a painted surface.......many hatches, not just a couple, then apply an adhesive tape, then lift the tape. If the small paint squares pull off on the tape, the painted surface has failed to adhere to the surface and you won't be happy with it.

 

Do a youtube video search for "cross hatch paint test". The paints used on those demonstrations generally pass, but you will get the idea how it works.

[PAR]

For those interested, I've been using Eastwood's single stage, two part acrylic urethane paint. It's about $120 retail per gal (catalyst/resin kit) and is durable, hard, very good gloss retention, etc,. etc., etc. I have only squirted the stuff, but it could be rolled and tipped. If it was, you'd have to work fairly fast and it's viscosity is designed to shoot, so it's a bit thin for hand work, but you could bulk it up with multiple thin coats (3 or probably more). It flows well and rivals the LPU's (two part, two stage urethanes) in most every regard, except price. Color and mixing choices abound, as it's an automotive product, so if you want pearl, metallic or flake, it's available.

[LennieG]

I decided to try and use Rustoleum Marine Topside paint, an oil based Alkyd. I am laying it on top of MAS Epoxy. I sanded a test area, which is a seat top still unattached to the boat but with one layer of Epoxy. I sanded the epoxy with 80 grit with a random orbital sander enough to dull the surface. Not a lot of sanding but it certainly changed the complexion of the seat. Next I put down a thin coat of the rustoleum primer (rustoleum)recommended for the paint, sanded and put down another coat of primer. Well, my hopes are diminished that this paint is going to work. While sanding the first primer coat there was flaking kind of....the paint came off too easy....not a lot of it but patches seemed to come off like there was no adherence. I cannot believe that more coats of paint are going to change anything. It had cured for two days in hot Florida temps. I never got to the point of simulating the cross hatch test because I think I learned everything I need to know.

Thanks to Howard for pointing out caution and I am glad I am not dealing with an entire boat with adhesion issues. I am giving up on this paint most likely prior to opening the can and adding a couple coats onto a primer that doesn't stick. Let me know if I am missing something but thankful for this forum and the guidance you guys provide.

[Hirilonde]

Did you clean off the blush before sanding?  Did you clean all of the dust from sanding off before priming?*

 

*brush or vacuum off first, then clean with a solvent

[LennieG]

Clean off the blush first? Well I didn't know of any blush, as in Amine Blush? No as I recall I did not do that. There was no stickiness, wetness or tackiness or appearance of non cure. The epoxy was hard and cured for a couple months.. First step was sanding, then I cleaned surface with a wet rag w water and ammonia.

Did I miss something important?

Thanks

[LennieG]

As I recall I did brush off the piece with a dry dust brisk first

[Howard]

Lennie:

 

Normal sequence would be to rinse off any blush first (MAS claims their product is "blush free", so for now, assume that was not the culprit), let it dry, then sand. Otherwise, if there is any blush, you just grind it in when you sand. After rinsing and sanding,  rinse again, let it dry and it should be OK to paint at that point, unless it has remnants of the chalky looking sanding dust after the last rinse. If that is the case, keep rinsing (scrub while you rinse) until it is clean and dust free once it dries.

 

Beyond that, without having seen what happened, difficult to troubleshoot beyond what has already been offered. For a surface that is supposed to be inert (epoxy), it does seem to have issues. Gelcoat for one, oil based paint for another.

 

Most paint systems seem to be designed for fiberglass, metal and wooden boats. Not many even mention epoxy coated plywood boats, so we are pretty much left to our own to find out what works and what doesn't. It seems that a two part LPU over epoxy primer has turned up the best results most of the time. Regrettably, it is also the most expensive and difficult to apply paint system.

[Hirilonde]

Another suggestion would be to use Alwgrip 545 epoxy primer (2 part).  It is an amazing primer over epoxy and under any finish paint.  But I suspect it is a cleaning issue, it usually is.  Anything to do with coating requires almost anal cleaning.  OCD people excel.

[LennieG]

Ok great advice all! There was definitely no visible blush, or residue or anything (the seat was hard and dry) but I guess these things are chemical and I may not detect what is really there. I may try another seat panel as I have time before actually painting and it would be great personally to avoid two part LPU for a couple reasons.....they all seem to want you applying with low humidity (50% or less) which I won't have for months most likely, and cross ventilation which I don't have as I am in a "tin box"storage room with a door on one end only. Further I hate to ask for a friends help on rolling and tipping with what seems like a potentially dangerous task. The polyurethanes scare me.

[LennieG]

Ok great advice all! There was definitely no visible blush, or residue or anything (the seat was hard and dry) but I guess these things are chemical and I may not detect what is really there. I may try another seat panel as I have time before actually painting and it would be great personally to avoid two part LPU for a couple reasons.....they all seem to want you applying with low humidity (50% or less) which I won't have for months most likely, and cross ventilation which I don't have as I am in a "tin box"storage room with a door on one end only. The polyurethanes scare me.

[PAR]

No solvent rinse when removing blush. In fact, this will just smear it around. It's water soluble, so a mild soap and/or just water. If you're not working in ideal laminating conditions, it's best to assume you have an amine blush, even if using a non-blushing formulation. Besides, since you're not working in ideal conditions, you'll have dust, bugs and other contaminates on the surface anyway, so wash it off.

 

Has anyone used the new "resurfacing" products designed to save old decks and cracked driveways? It's basically thick (gap filling) acrylic paint, from my understanding, but I was just wondering if anyone has tried it yet. I might get an opportunity soon.

[LennieG]

Thanks for taking the time here Paul, and the info. Thanks also to Dave and Howard and the others.

[Howard]

BTW, as I understand paint chemistry, acrylic means water soluble or water based, yet once they dry, water does not affect them. These do seem to be compatible with epoxy. I think Charlie Jones has said he has used these safe, easy to apply, yet durable acrylics on boat interiors (enclosed boats) for years. If so, a high quality, semi-gloss exterior acrylic house paint may have a place for some epoxy covered boats. If anyone can confirm this with actual experience, brand names and very specific product line references would be helpful.

 

Doubt they would hold up to exterior exposure nearly as well as a good two part LPU, but for interior use, they might work.

[PAR]

Acrylic and latex are now terms used interchangeably, though they are different. Acrylics are what are used now typically with acrylic or vinyl resin. Most house paints are vinyl, while the automotive and "artist" types of paints have more or higher percentages of acrylic resin, making them harder and more durable. This is why I've been using the automotive water borne acrylics. Though these are designed to spray, they can be had in different formulations, some (the single stages) can be roll and tipped. Technically, there aren't any real "latex" paints anymore. They haven't used real rubber resins in paints for a few decades now, but the term has stuck.

 

These paints can be used with few difficulties over epoxy and/or epoxy primers. They clean up easily and aren't your pop's old house paint. You can tell by price and reading the content labels as to what you have. House paints are typically about $20 to $40 a gallon and these tend to be fairly soft and "chalk" up in a few years, especially if a flat or other, nearly flat finish. The glosses are better at this, holding their shine longer. The better acrylics can run from $50 to $120 a gallon. These are hands down better products at about half the price of the standard two pack, two stage LPU's. Their performance is similar to the 2K LPU's, without the need for special reducers, wetting agents, etc. too. I've used house paints inside boats for years and they work fine, except in high traffic areas. I don't trust them on a boat's hull, though many a workboat has used them successfully for generations. So, if looking to save some money, use house paint inside the boat and save the "good" stuff for the high traffic areas and the exterior.