Please Help With Paint Questions

I have some paint questions.

1) VOC solvents- How much of a high build epoxy primer should be solids? I have some high build industrial primer available locally and it is 47% VOC! This sounds like way too much to me. Is that correct? Coverage of 133 sqft at 7 mils. Is that a rip off because it's only half a can of paint, or is that normal for a sprayable epoxy primer you don't have to thin?

2) Solvents in general- I got some lacquer thinner to clean out the spray gun. It's also recommended by Gougeon to thin epoxy if you so desire. HOWEVER, when I put a piece of corecell into a cup that has hardened epoxy in it, then pour in lacquer thinner, the foam curls/shrivels and the epoxy goes soft. This scares the Hell out of me!!! I don't want to put solvents anywhere near my epoxy boat becauof this. What do I do??? What is safe?

 

That sounds about average. What are you spraying?

 

Thank you for the input. It is called MoPoxY HB. High Build Epoxy Primer 40-DR-5. Got a very good price of $35/gal. It is called BLP Mobile Paint Company.

Should I be worried that solvents destroyed corecell and epoxy in my little straight solvent test? It softened the weeks old, cured epoxy and shriveled/curled the core cell. Don't really want to weaken the $600,000 value boat.

I'm petrified.

 

If you have a $600,000 boat, a couple of hundred dollars difference in paint price should not concern you. A bad paintjob can cost you a fortune. Did you try the primer on a piece cut from the hull?

 

It's that I don't know anything about paint.

I tried straight solvent on epoxy and core cell the hull was made from. They both melted a little.

I did not try the primer on the same materials. Good idea. I will test that tomorrow.

Fear is getting in the way of clear thinking here.

 

West System does NOT recommend thinning their epoxy, though if you do (and they know some will) they recommend denatured alcohol, not lacquer thinner. There's no reason to thin epoxy and unless you have a very strong grasp on the chemistry involved, you shouldn't even consider it.

Yes, lacquer thinner will soften both products, though you can get epoxy formulations that are much more resistant to lacquer thinner, they're a considerably more costly and not commonly available.

Epoxy primers come in several configurations and formulations, some water borne, some relatively solvent free, with others high in solvents. Again, the chemistry thing applies, so taking a guess at what "seems too much" without a clue about these formulations is well - just guessing. I'm not trying to offend you, but this is a complex and convoluted subject, most just don't have much of a grip on (and you don't need too either).

Lets start from square one - what are you painting - the substrate that will receive the paint? I'll assume it's an epoxy sheathing over a core. In this case you'll want a low solvent or water borne epoxy primer. There are lots to choose from, but sticking with the "usual suspects" will generally bring the best results (well at least predictable results). Once the primer is down, the compatible top coats (anti foul, shinny stuff, whatever) go down and the underlying epoxy/core is protected. It's a system and all the "parts" need to be in place, primer and/or tie coats, plus top coats.

 

Thanks, PAR. I don't think anyone could offend me here. You could say, "listen, stupid, this is how it's done" and I'd be listening and thanking for the help. I have very limited knowledge of paint.

The other day I did read a West System article on thinning epoxy (not that you should or need to). It came up while Google searching for the effects of solvents on epoxy. They suggested laquer thinner or acetone to thin it.

But the paints I'm looking at using are from this company. BLP Mobile Paint Corporation. The high build is comparable to the DuPont Nason line hight build primer. Same amout of VOC. VOCs are xylene, toluene, isopropyl ketone.

So, the paint system is BLP Mobile high build primer then their topcoat 2 part acrylic urethane.

 

I have used the Dupont product and liked it. What is the price difference?

 

This is paint, not epoxy.

 

Yeah, the Dupont is every bit as good as Awlcraft 2000. Exact same paint. This stuff, which is used locally in the south, is same as Dupont, so also good.

Do keep in mind I would have worried about the solvents in Awlgrip 545 just as much. And... Awlgrip 545 has the same amount of solvents. Approx 50% of the can. Here is the Awlgrip 545 VOC: White Base 435 g/lt or 3.6 lbs/gal. Gray Base 426 g/lt or 3.6 lbs/gal. Converter 616 g/lt or 5.1 lbs/gal.

So do I still need water base? I thought everyone used Awlgrip 545 over epoxy substrates, no?

Here is the Imron/Awlcraft 2000 clone I got a sample gallon of. It is $35/gal, which is incredible compared to what they charge for Awlgrip High Build. Which isthe exact same thing.

https://www.blpmobilepaint.com/about_us.html

I have to wonder why so many people do not use industrial aliphatic linear polyurethanes when they are the same pants. Fear?

My fear is solvents, which all the marine paints have in the same amount as BLP Mobile.

https://www.blpmobilepaint.com/about_us.html

And this is the actual paint/high build.

https://www.blpmobilepaint.com/marinefinishtopside.html

72-line Mothane is the Awlcraft 2000/DuPont Imron. $60/gal
40-DR-5 HB is the high build. $35/gal.

The salesman is here at the marina every week and the yard buys paint from them.. The day after the salesman leaves, the truck delivers the product. Did I discover a sort of gold mine?? How come nobody else uses this stuff? Because it's a regional business?

 

I have been painting boats with IMRON for many years and find it the easiest to work with. Unless you are in ideal conditions, it is the paint that has the most combination of hardeners, reducers and additives to compensate for conditions.

 

Thanks, Gonzo. PAR, I'm hoping to get your input as well, if possible. The solvent is the same as Awlgrip 545 primer. Is this dangerous to spray over an epoxy glass and core cell hull?

Do I need to find the water based or low solvent?

Has anyone here sprayed 545 or another high VOC primer over epoxy glass and corecell boats?

How was the longevity?

 

545 over epoxy/glass is very common, 545 is a nice primer but that doesn't mean the local stuff is not just as good, lots of people use awlgrip products because they advertise heavily,like West. I think you need to talk to local painers that use the product, then buy a quart and do some test panels. BTW,we also use Nason on our own boats and cars.

Steve.

 

Thanks, Steve. I have a gallon of the epoxy primer to try out. Asked for a sample, they gave a whole gallon, plus the quart of the second part for free. Pretty impressed with that.

 

2K Epoxy primers over here in Europe have their own specific thinner. It is not the same as 2K acrylic automotive/marine paint thinners (we call it cellulose thinners) and should not 'attack' epoxy builds. I have used it (epoxy high build primers) successfully quite a bit with 2K marine or automotive paints on top. Never noticed any problems at all, or softening. In fact the high build primers are excellent for filling in any tiny pinholes often left in an epoxy surface.

I'd second trying out on a scrap piece if concerned. I have only run into hardener compatibility problems between brands when using 2K paints ie a 'Universal' air dry hardener does not always work with a 2k paint even though the systems are acrylic/polyurethan blends. If I mix a small sample and I see any pearlescing - it is not compatible.