- Joined
- Mar 1, 2000
- RO Number
- 6
- Messages
- 231
The first thing to do is make sure all of the mud work is straight (base fiberglass & roving). The easiest way to do this is with an air file. If an air file isn't available then any kind of long block will work. They are inexpensive, and they work well. Block all of the mud work until it feels smooth when you run your hand over it. Then take some black spray paint (any kind of cheap paint will work) and spray over your body work. Just cover the mud, you don't need to put a heavy coat on. When this dries, Go over it with the long block with 80 grit. This will show you the high and low spots in your mud work. Fill any low spots with more putty and block that down. Spray it again with the paint and when all of the paint sands off in a uniform manner than the mud work should be straight enough. When you
are blocking your body work avoid the temptation to put uneven ressure on the long block in order to sand a high spot down a little.........it will show in the finished product.
Once you are satisfied that it's straight enough blow the entire area off with a high pressure blower. This will open any pits up that have filled with dust. If the pits are large, say bigger than a pin head, then you need to fill them with putty and block them down. Look at any areas surrounding the body work. If you see bare glass, then it most likely will have very tiny pin holes in it. Take a little gelcoat and mix it with cabosil until you have a smooth paste about the consistency of cake frosting. Catalyze it and with your finger smear some on any bare glass you see, and any small pits in the mud work. Allow this to dry and sand it smooth with 220. You may still have some small pits here and there, but if they are small it shouldn't be a problem. Next you want to take 220 and sand the entire area extending about 4 to 6 inches into the area of good gelcoat. It looks like at least 2 colors will be sprayed so take care to tack the white area, if you don't tack it you may end up with a pink halo around the white spray. Mask off the area you want to spray first. If you are shooting white first, mask off the red area, and vice versa when you spray the red. If there is any hardware in the area to be sprayed, it's best to remove it if at all possible, making sure to get any sealant off also. Paper the area up very good........overspray has a way of finding the tiniest hole in the masking paper. In fact it's best to cover the whole boat before you spray, and keep it covered until the whole job is complete.
One the covering and masking is finished you can shoot the gelcoat. There are quite a few additives to mix with the gelcoat to thin it and aid in the drying process, but if none are available acetone works pretty well. When you thin gelcoat with acetone start with
just a few drops, and add it like that until you get the consistency of a thin milkshake. When satisfied with the consistency catalyze it with MEKP. the proper amount is about a 2% mixture. 5cc's to an 8oz cup of gelcoat will give you about 8 to 10 minutes of spraying time. When you shoot the gel, apply it in long even coats. If pits appear, avoid holding the gun in one spot to fill them, just keep moving back and forth. When you empty the gun, or it starts to kick, clean it immediately with acetone, dry it and mix another batch of paint. If you still see pits, spray a spot on you masking paper and using a razor blade fill the pits with the gel you sprayed on the paper. Then once again spray the area in long smooth even coats. Allow the white area to tack up, remove the paper from the red area and spray it the same way. One word of caution, when you get to the edge of your repair area, do not spray on the tape line of the masking paper. Spray up to it, but not on it.....you don't want any sort of visible paint line.
Give your repair at least a 24 hour period to thoroughly dry, possible 48 hours depending on the temperature. Without the proper additives, gelcoat take a very long time to cure, so it's best to wait an extra day if necessary. When you are sure it's fully cured remove the masking paper from the repair area and wipe the whole repair with a rag soaked with acetone. This will remove any contaminates that have come to the surface. Once again,
make absolutely sure it's dry, the acetone will remove the gelcoat if it isn't dry. Even when it's dry you will see some pigment on the rag, but that isn't a problem if the paint is cured.
Now you must work the spray down to that nice hard finish. Start with 320 sandpaper on a block or air file and work the spray the same way as the mud work. The idea here is to smooth the gel and remove all traces of orange peel. This is tedious work and you will use a lot of sand paper, but for a good straight finish it's necessary. After you have removed the orange peel switch to 600 sandpaper. the idea here is to remove the 320 sand marks, and this won't take quite so long. When you think you have sanded enough buff the repair with a rather heavy compound, some thing like 720. This will take out a lot of sand marks and put a fair shine on the finish. take a trouble light and look closely at the repair. Look for orange peel, paint lines and pits, if you find any sand them out. After you have all of you sand marks out, put on a new buffing pad and buff the repair with a fine finishing compound. 2000 grit is excellent.
If you happen to sand through in places these can be resprayed using the same processes as before, only on a smaller scale. Look the repair over and make sure you are satisfied with it. Do not expect it to be a perfect repair. Gelcoat is extremely hard to repair with
no traces. A slight waviness is to be expected, so don't expect results that can only come from years of experience. Remember how it looked before you started and be proud of the job the accomplished.
A word of caution when dealing with polyesters, Mekp, and acetone. Polyesters WILL COMBUST. Any unused gelcoat that has been catalyzed should be poured into a bucket or can that is filled with water. The same goes for putty, even if it's hard, put it in the water, and let it sit for several hours before you throw it away. MEKP is very reactive and should be kept away from all metals. Acetone is extremely flammable and should be treated as such. Any rags with acetone in them should be spread out and allowed to air dry, don't just throw them away of toss them in a pile. It would be a shame to put so much work into this repair only to have the boat damaged further in an accidental fire.
are blocking your body work avoid the temptation to put uneven ressure on the long block in order to sand a high spot down a little.........it will show in the finished product.
Once you are satisfied that it's straight enough blow the entire area off with a high pressure blower. This will open any pits up that have filled with dust. If the pits are large, say bigger than a pin head, then you need to fill them with putty and block them down. Look at any areas surrounding the body work. If you see bare glass, then it most likely will have very tiny pin holes in it. Take a little gelcoat and mix it with cabosil until you have a smooth paste about the consistency of cake frosting. Catalyze it and with your finger smear some on any bare glass you see, and any small pits in the mud work. Allow this to dry and sand it smooth with 220. You may still have some small pits here and there, but if they are small it shouldn't be a problem. Next you want to take 220 and sand the entire area extending about 4 to 6 inches into the area of good gelcoat. It looks like at least 2 colors will be sprayed so take care to tack the white area, if you don't tack it you may end up with a pink halo around the white spray. Mask off the area you want to spray first. If you are shooting white first, mask off the red area, and vice versa when you spray the red. If there is any hardware in the area to be sprayed, it's best to remove it if at all possible, making sure to get any sealant off also. Paper the area up very good........overspray has a way of finding the tiniest hole in the masking paper. In fact it's best to cover the whole boat before you spray, and keep it covered until the whole job is complete.
One the covering and masking is finished you can shoot the gelcoat. There are quite a few additives to mix with the gelcoat to thin it and aid in the drying process, but if none are available acetone works pretty well. When you thin gelcoat with acetone start with
just a few drops, and add it like that until you get the consistency of a thin milkshake. When satisfied with the consistency catalyze it with MEKP. the proper amount is about a 2% mixture. 5cc's to an 8oz cup of gelcoat will give you about 8 to 10 minutes of spraying time. When you shoot the gel, apply it in long even coats. If pits appear, avoid holding the gun in one spot to fill them, just keep moving back and forth. When you empty the gun, or it starts to kick, clean it immediately with acetone, dry it and mix another batch of paint. If you still see pits, spray a spot on you masking paper and using a razor blade fill the pits with the gel you sprayed on the paper. Then once again spray the area in long smooth even coats. Allow the white area to tack up, remove the paper from the red area and spray it the same way. One word of caution, when you get to the edge of your repair area, do not spray on the tape line of the masking paper. Spray up to it, but not on it.....you don't want any sort of visible paint line.
Give your repair at least a 24 hour period to thoroughly dry, possible 48 hours depending on the temperature. Without the proper additives, gelcoat take a very long time to cure, so it's best to wait an extra day if necessary. When you are sure it's fully cured remove the masking paper from the repair area and wipe the whole repair with a rag soaked with acetone. This will remove any contaminates that have come to the surface. Once again,
make absolutely sure it's dry, the acetone will remove the gelcoat if it isn't dry. Even when it's dry you will see some pigment on the rag, but that isn't a problem if the paint is cured.
Now you must work the spray down to that nice hard finish. Start with 320 sandpaper on a block or air file and work the spray the same way as the mud work. The idea here is to smooth the gel and remove all traces of orange peel. This is tedious work and you will use a lot of sand paper, but for a good straight finish it's necessary. After you have removed the orange peel switch to 600 sandpaper. the idea here is to remove the 320 sand marks, and this won't take quite so long. When you think you have sanded enough buff the repair with a rather heavy compound, some thing like 720. This will take out a lot of sand marks and put a fair shine on the finish. take a trouble light and look closely at the repair. Look for orange peel, paint lines and pits, if you find any sand them out. After you have all of you sand marks out, put on a new buffing pad and buff the repair with a fine finishing compound. 2000 grit is excellent.
If you happen to sand through in places these can be resprayed using the same processes as before, only on a smaller scale. Look the repair over and make sure you are satisfied with it. Do not expect it to be a perfect repair. Gelcoat is extremely hard to repair with
no traces. A slight waviness is to be expected, so don't expect results that can only come from years of experience. Remember how it looked before you started and be proud of the job the accomplished.
A word of caution when dealing with polyesters, Mekp, and acetone. Polyesters WILL COMBUST. Any unused gelcoat that has been catalyzed should be poured into a bucket or can that is filled with water. The same goes for putty, even if it's hard, put it in the water, and let it sit for several hours before you throw it away. MEKP is very reactive and should be kept away from all metals. Acetone is extremely flammable and should be treated as such. Any rags with acetone in them should be spread out and allowed to air dry, don't just throw them away of toss them in a pile. It would be a shame to put so much work into this repair only to have the boat damaged further in an accidental fire.