Epoxy based Filler Primer?

What is this epoxy topcoat you reference? i am not aware of anyone in the industry using an epoxy topcoat,always polyurethanes in the 2 part paint. Perhaps you are using Easypoxy 1 part.
Steve.

 

Um, the whole boat is already made from cheap polyester resin

The reason I suggested the car version is because it doesnt have BOAT written on it, therefore it will usually be cheaper.

 

I agree with Steve in that most are using polyurethanes (single parts or LPU's) and automotive applications are now mostly acrylics. Easypoxy is a single part polyurethane, not an epoxy.

Sabahcat, what you call automotive bog, we call Bondo (a brand name over here) and both have a few nasty tendencies. These polyester fillers absorb moisture, the tend to "circle" out of depressions with vibration or expansion/contraction cycling, they don't stick very well to most surfaces, including polyester and it stinks.

I'd tend to agree that it's a cheap polyester boat, so don't go nuts, but expecting repairs to stay put is a goal to nail.

Sorry about the deal with the PC-11 stuff. It works wonders, if you've stripped out a spark plug hole thread, but can be a ***** to sand. Maybe you didn't prep the surface as well as could have been and it's not too well stuck. Take a chisel to the lumps first and see if you can explode most of it out of the holes and depressions. Yep, a belt sander will likely be your best friend for a while. A well placed drill bit also can remove huge hunks of this stuff. Turn it real slow and bear down on it real good and with luck you'll pop a few loose. Of course, you''l want to be careful about not drilling right through the hull, right?

 

Thanks for the suggestion of a chisel, that might save some time. That is an interesting idea of using an electric drill with a very large bit. I'm not sure I'm brave enough to try it, but maybe.

 

Yes "Boat" stuff does seem to add to the price.

Perhaps it is not very practical, but I like to make repairs that will increase the life expectancy of a boat. I don't see a good reason that a well maintained boat should ever wear out. so, epoxy over polyseter makes sense to me. The epoxy has less permeability to water and will help preserve the polyester.

 

Steve, I've seen the can only once. I don't remember the brand name, but it was one that I had never seen before. I looked a the contents and it does have polyamide as the primary ingredient. I'm fairly sure it was not Easypoxy. I'll try to get back to you with the brand name.

 

Don't be fooled, using parts of the epoxy molecule is an advertising and marketing gimmick. Unless it's a two part paint with the complete bisphenyl A molecule (typically it's - diglycidol ether of bisphenyl A), then it's not epoxy.

Put a stop collar on the drill bit.

 

Yes, I agree there is lots of room for gimicks, and I am skeptical of this "epoxy" paint. After all, it is from the same guy that recommended the PC11 as a filler. I'll get more info. And since we will likely use it, we will have a test case.

 

I'm telling you, it would be wise to ignore the PC-11 guy . . .

 

I agree with you PAR, however, on this project i'm just a technical advisor (and perhaps free labor), not the executive with the checkbook.
After the PC-11 recomendation, I believe this salesman has lost credibility with management. But we already have this epoxy paint, and I expect we can make it work. Unless the paint is just really bad, we can add something on top of it.

I think I'll suggest that we apply a small test section first.

Do you have any suggestions on how to test the durability of this paint, such as painting it on plywood and boiling it? I can't think of where to get a sample size of polyester fg. Or perhaps baking it in an oven? If we did such a test, what should be the standard of comparison?

 

Prep the area normally (the hull) prime and offer several days to cure, then top coat. Again several days to cure, as they appear dry, but aren't for at least a week.

Once you're sure it's dry, lightly scratch the surface with a knife in a cross hatch pattern. Apply a wide piece of duct tape over the paint, then burnish it down with a hard object. Next, grab the end of the tape and yank it off in a very quick, violent motion. You'll quickly figure out how well the paint is stuck.

Is this paint a two part product?

 

Yes, it is a 2 part paint.

 

Thanks, that sounds like a good technique.

 

If your paint is a two part, does one part have a strong smell? What does it smell like if it is strong, ammonia maybe? A real epoxy paint will not have a very strong smell, though a noticeable ammonia smell can be had when you first open the can. The very high vapor pressure (of typical epoxy molecules) will quickly disperse this smell. Once the can is open a few minutes there should be very little odor, if it's an epoxy.

The "scratch test" above is an industry standard and works quickly. Use the stickiest darn tape you can find and make sure the paint is good and cured, which is the part most novices preforming this test screw up on. Alkyd based paints (oils) can take as long as a month, Acrylics are much better and the true polyurethanes can be dry in a week. Naturally, environmental conditions can really screw up the drying time. Don't peel the tape off, give it a big jerk, trying to remove it in one shot.

 

I got the name of the paint that we currently have.

Palgard produced by Pratt & Lambert

http://www.prattandlambert.com/products/industrial-maintenance/paint/palgard-epoxy/index.jsp