ondarvr
Supreme Mariner
- Joined
- Apr 6, 2005
- Messages
- 11,527
Re: Gel Coat application
TG<br /><br />It sounds like you want to use gel coat, here's the info. Start with 80 grit and sand the entire surface, fill the defects and sand them down, gel coat won't fill all the imperfections. Use a Binks spray gun with a 66 or 67 tip, the 66 will give a smoother spray job, use the Duratec clear it will help it flow and level. I can't officially recommend Duratec because we don't advise that you mix anything that we don't make and have tested in our lab, but many people use it with good results. The temperature needs to be above 60 and I would recommend it be above 70 for it to cure correctly. Because you will be sanding it down you will need to apply at least 25 mils, if it's got a lot of orange peel it will need to be thicker. You need to apply it in three or four passes of around 7 mils each. Less than that and it won't level and flow, more and you risk getting porosity. Catalyze it at 2% no more, no less, Mix it very well. Don't add a bunch of styrene or acetone, 5% is OK (but still not recommended), more than that and you may run into problems with weathering, cracking and curing. the Duratec will help the surface cure tack free, but you still may need to add wax to get a good surface to sand on, if it's not cured completely it will just gum up the sand paper. NOT ALL gel coats will cure well in this type of application, some will not cure well on the back side no matter what you do. If you get all of this done without any of the gel coat getting hard inside the gun (you only have about 12 minutes or so to use it up) you did a good job.<br /><br /><br />Leave it sit for a few days before you start sanding. Good sand paper is expensive and you will use a bunch of it. If there's a lot of orange peel start with 180 or 220 grit on a DA, if it's somewhat smooth start with 320 or so. After a few days of sanding and some possible respraying of areas that you sanded through, or were too rough to sand down and you needed to fill, you can start using finer sandpaper. Don't go to the very fine papers though it doesn't always help in getting get a better finish, 800 is about all thats needed. You can go finer, but you need to use the correct buffing pads and compounds used in multiple steps to notice a difference. If you decided to use any color other than white, all of these steps, including the spraying, will be more difficult.<br /><br />Because gel coats are not designed or formulated<br />to be used in this way, it will not retain it's color or gloss as well as it would as when it's used in a mold.<br /><br />This will take about a week if you work on it a lot, it will take longer if you don't have a good place to work on it.<br /><br />Now this is what's involved in painting it.<br />Sand it with 320 or so, fill the pits and scratches, spray it with primer to fill the minor imperfections, wait an hour or so depending on temp and type of primer, then lightly sand it down. Clean and tape it off, spray it with a good 2 part PU, pull the tape and go have beer. Let it dry (cure), put it in the water and go fishing. <br /><br />The gel coat method will take me a week or two to complete. With paint, I can do it in less than one day.
TG<br /><br />It sounds like you want to use gel coat, here's the info. Start with 80 grit and sand the entire surface, fill the defects and sand them down, gel coat won't fill all the imperfections. Use a Binks spray gun with a 66 or 67 tip, the 66 will give a smoother spray job, use the Duratec clear it will help it flow and level. I can't officially recommend Duratec because we don't advise that you mix anything that we don't make and have tested in our lab, but many people use it with good results. The temperature needs to be above 60 and I would recommend it be above 70 for it to cure correctly. Because you will be sanding it down you will need to apply at least 25 mils, if it's got a lot of orange peel it will need to be thicker. You need to apply it in three or four passes of around 7 mils each. Less than that and it won't level and flow, more and you risk getting porosity. Catalyze it at 2% no more, no less, Mix it very well. Don't add a bunch of styrene or acetone, 5% is OK (but still not recommended), more than that and you may run into problems with weathering, cracking and curing. the Duratec will help the surface cure tack free, but you still may need to add wax to get a good surface to sand on, if it's not cured completely it will just gum up the sand paper. NOT ALL gel coats will cure well in this type of application, some will not cure well on the back side no matter what you do. If you get all of this done without any of the gel coat getting hard inside the gun (you only have about 12 minutes or so to use it up) you did a good job.<br /><br /><br />Leave it sit for a few days before you start sanding. Good sand paper is expensive and you will use a bunch of it. If there's a lot of orange peel start with 180 or 220 grit on a DA, if it's somewhat smooth start with 320 or so. After a few days of sanding and some possible respraying of areas that you sanded through, or were too rough to sand down and you needed to fill, you can start using finer sandpaper. Don't go to the very fine papers though it doesn't always help in getting get a better finish, 800 is about all thats needed. You can go finer, but you need to use the correct buffing pads and compounds used in multiple steps to notice a difference. If you decided to use any color other than white, all of these steps, including the spraying, will be more difficult.<br /><br />Because gel coats are not designed or formulated<br />to be used in this way, it will not retain it's color or gloss as well as it would as when it's used in a mold.<br /><br />This will take about a week if you work on it a lot, it will take longer if you don't have a good place to work on it.<br /><br />Now this is what's involved in painting it.<br />Sand it with 320 or so, fill the pits and scratches, spray it with primer to fill the minor imperfections, wait an hour or so depending on temp and type of primer, then lightly sand it down. Clean and tape it off, spray it with a good 2 part PU, pull the tape and go have beer. Let it dry (cure), put it in the water and go fishing. <br /><br />The gel coat method will take me a week or two to complete. With paint, I can do it in less than one day.
) the natural lines the boat has and they are really very elgant. So lots of sanding and prep on the bow to remove the pits. And i really dont like the aqua marine stripe it really does nothing for the boat so refinshing is in order. I buffed the top of the boat and could hardly believe how well it cleaned up it was incredible. Hence my respect for gel-coat, never have i seen a finish clean up so well.(and no burning) <br /><br />I guess i just have decided not to go just halfway, i am doing quite a bit of cosmetics,floor's, carpet,upholstry no glass thank god. Being in the automotive indrustry give's me a edge with recon i know quite a few tradesmen who help and guide me thourgh this process. When the project is @ completion i will post the progress and steps along with the final out come.