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In comparison...epoxy primer on its BEST day cannot hold candle to the properties of what gelcoat can do. They cannot even be considered even being close. The ONLY product that remotely comes close to gelcoat is polyester primer..and it is still NOT the same. Because show me where you see a boat or fiberglass item that is left outside in water or just left outside that is in polyester primer. You won.t BUT you will see fiberglass parts all having gelcoat used on them in their process of beign made for a reason...
I clean up my gelcoat gun and then I apply the PVA . 5-10 minutes generally.
DUB
Okay DUB
I have a sailboat made in 1971. Gelcoat still shines after I hit it with rubbing compound every 5 years!!
Thanks, I understand
In comparison...epoxy primer on its BEST day cannot hold candle to the properties of what gelcoat can do. They cannot even be considered even being close. The ONLY product that remotely comes close to gelcoat is polyester primer..and it is still NOT the same. Because show me where you see a boat or fiberglass item that is left outside in water or just left outside that is in polyester primer. You won.t BUT you will see fiberglass parts all having gelcoat used on them in their process of beign made for a reason...
I clean up my gelcoat gun and then I apply the PVA . 5-10 minutes generally.
DUB
ok DUB but how long do I leave the pva on before rinsing it of. Alway appreciate your advice.
Last edited by twinpack; Jan 30, 2019 at 06:59 AM.
I give it about 24 hours at 70 degrees F myself. OR...maybe longer if I need to heat up the body due to shooting the gelcoat during the winter months and wanting to make sure I get it hot.
In the summer months I pull it outside in the sun and let it get really hot
may seem like a dumb question but what does the top coat of PVA over the GEL coat do?
From what I understand, gelcoat is designed to be sprayed into a mold and then covered with fiberglass , so needs to be sealed off from the air to cure properly. Yo can also achieve this by adding wax to the last coat of gelcoat, which floats to the surface and seals it off.
I just finished washing off the PVA , I was going to put the wheels on the car and push it outside , but ended up just leaving it in the shop and washing it off there, the stuff comes off really easy, you can actually catch an edge and peel it off ,but that would take forever, it dissolves really fast, I gave it a scrub with one of those green dishwashing scrubbers and a good rinse, and its all gone ready to sand. Took maybe half an hour to do the whole car.
From what I understand, gelcoat is designed to be sprayed into a mold and then covered with fiberglass , so needs to be sealed off from the air to cure properly. Yo can also achieve this by adding wax to the last coat of gelcoat, which floats to the surface and seals it off.
I just finished washing off the PVA , I was going to put the wheels on the car and push it outside , but ended up just leaving it in the shop and washing it off there, the stuff comes off really easy, you can actually catch an edge and peel it off ,but that would take forever, it dissolves really fast, I gave it a scrub with one of those green dishwashing scrubbers and a good rinse, and its all gone ready to sand. Took maybe half an hour to do the whole car.
M
My buddy came up today to help me start blocking out the car, I thought I remember someone telling me at some point that gelcoat is easy to sand, ( they lied) it's a grunt, but between the two of us we got the entire car done , minus the doors in 7 hours, so not too bad. We ended up using a D/A with 60 grit to knock it down a bit as it is very orange peely , then blocking everything with 80 grit on dura blocks until all the orange peel was gone. DUBS suggestion to use black gelcoat is the way to go , it gives you a perfect guide coat. I'm going to hit the doors in the morning before Super Bowl, and then back to masking for polyester primer.
Dave... I think I was the one who said gelcoat is easy to sand. But I also am so used to sanding Vette Panel Adhesive....I guess my way of thinking is messed up.
And I am glad that you see why using black gelcoat is a much faster way of prepping it due to you can see the color change when blocking it....which also goes along with why I mentioned using acetone to thin the coats to better allow the gelcoat to flow out and to not be so textured..
Glad you got it blocked. and the same can hold true to when you apply the polyester primer. Using acetone to better allow the surface to flatten out will make the next stage of blocking go that much quicker. The polyester primer will be a tad bit easier due to all of the talc in it as a filler that the gelcoat did not have in it. And as you know...this stage of sanding is where it all comes down to. I wet sand with 400 grit myself and use the 3M dry guide coat powder. And with the polyester primer being really slick and having very little texture...it does not take much for me to get the primer slick.
Not knowing what you have done with the inside of the doors where they are steel. Hopefully any gelcoat that may have gotten on it can be easily removed so an epoxy primer can be shot on the bare steel areas and then the polyester primer on it after the epoxy has cured.
I used epoxy primer to seal all of the fiberglass work on the corvette back in 2013 before using a 2000k primer, blocking, spraying again, blocking and spraying, blocking again, and repeat, then handing it off to a guy who knows how to spray paint in a professional booth. This is what I learned from all of those hours of removing paint, repairing glass, spraying primer, sanding straight. My glass repairs are excellent, I can block sand ok, but spraying uniformly and consistently? Not so much. Honest assessment. I wanted a show car finish. Got one. If anyone asks who painted it, I tell them the name of the guy who sprayed the final finish, but also add that I did all the prep work so the flaws are on me. The response is usually, what flaws?
As for gelcoat. I have a GEM cart I use at work. It had some body damage so I made the necessary repairs to the fiberglass panels, then bought gelcoat from a boat supply house. It came tinted in a nice shade of blue. I sprayed the body work, multiple coats. Tip, spray it white first to cover the repairs, then use the tinted stuff. I thought, oh boy, now I have a bullet proof hard shell finish. Wrong. Its sealed nicely from the weather, but after a few yrs of use, it has scratches, gets nicked up etc. I honestly believe the satin black epoxy primer I sprayed in the engine compartment and underbody of the Corvette and left un-top coated are holding up as well or better than the gel coat on the GEM cart. Just my observance.
i don't really know yet, I'm going to start a new thread, to get some answers on how to proceed from here, I am going to be using Base clear, not sure what brand
I used epoxy primer to seal all of the fiberglass work on the corvette back in 2013 before using a 2000k primer, blocking, spraying again, blocking and spraying, blocking again, and repeat, then handing it off to a guy who knows how to spray paint in a professional booth. This is what I learned from all of those hours of removing paint, repairing glass, spraying primer, sanding straight. My glass repairs are excellent, I can block sand ok, but spraying uniformly and consistently? Not so much. Honest assessment. I wanted a show car finish. Got one. If anyone asks who painted it, I tell them the name of the guy who sprayed the final finish, but also add that I did all the prep work so the flaws are on me. The response is usually, what flaws?
AS mentioned so many times is that a person can use what they want and apply it how they want ...as many times as they need to and still get a show car finish if certain procedures are employed.
Heck..I can get a show quality job using lacquer primer and lacquer paint....like I have done many times a long time ago. But in today's current technology...the lacquer is out dated. Because there are products that out surpass it when it is subjected to certain environmental issues. The same holds true when considering what type of primer to use and all that. Due to they are not all the same.....regardless on how well they work.
Originally Posted by Sunstroked
As for gelcoat. I have a GEM cart I use at work. It had some body damage so I made the necessary repairs to the fiberglass panels, then bought gelcoat from a boat supply house. It came tinted in a nice shade of blue. I sprayed the body work, multiple coats. Tip, spray it white first to cover the repairs, then use the tinted stuff. I thought, oh boy, now I have a bullet proof hard shell finish. Wrong. Its sealed nicely from the weather, but after a few yrs of use, it has scratches, gets nicked up etc. I honestly believe the satin black epoxy primer I sprayed in the engine compartment and underbody of the Corvette and left un-top coated are holding up as well or better than the gel coat on the GEM cart. Just my observance.
Believe what you like.... but gelcoat is not chip resistant...and neither is any epoxy primer or any spray on product. Heck...even powder coating is not 100 % chip resistant.
Using gelcoat and the properties it has going for it and what it does in comparison to any other product is where most people get messed up and use a product that will work and they feel it is just as good...when it is not..."just as good". Like I said....I can do a car all in lacquer and it would be awesome...but THAT does not make it better.
Put that car under car cover and stick in a humid garage and let it sit and see what happens. ...and have many Corvettes in the same garage covered up and have used different primers and one with gelcoat and see what happens when you pull the car covers back. You could pick out the gelcoated Corvette...and possibly the one that used polyester primer. Due to the paint not bubbling/blistering...or has the very least amount of it.
How do I know this example is true....because many of the Corvettes I do that have gelcoated fiberglass bumpers on them and the body was not coated in gelcoat or even a polyester primer....when the car was put in a bad storage environment...when the car cover was peeled back...the body has bubbles in the paint all over EXCEPT for the bumpers that were gelcoated.
I guess I have the luxury of living in the the desert. No humidity. Almost 5 yrs since final finish. I cover it in a garage. Paint is still awesome. But, point taken. One size does not fit all.
I guess I have the luxury of living in the the desert. No humidity. Almost 5 yrs since final finish. I cover it in a garage. Paint is still awesome. But, point taken. One size does not fit all.
AGREED....'One size does not fit all'...which is why I wrote humid garage. In my area you would be shocked on how fast things can happen if certain precautions are not taken.
