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I have a black 08 24ssv and anytime I try to sand it to smooth out a rock chip or a scratch the gelcoat sands through, turns white and won't buff out as if the boat was molded with white gel and then sprayed with black over it. It sucks if they really tried to save the tiny difference in money by using white gel and then a top color gelcoat later.
That really doesn't sound right. I've never heard of Supra painting a boat at the factory. You sure it wasn't repaired and/or painted by someone before you?Quote:
Originally Posted by sailnaked6842
What you describe does suck, but seems odd. I have an 09 24SSV with a black hull and have buffed out dock rash with excellent success.
I agree. Is it like that all over the boat?Quote:
Originally Posted by wotan2525
From my understanding the gel coat is not that thick, maybe you have sanded/buffed through it and are getting to the fiberglass =/
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lets see some pics
Hey Doc, here's some pictures. It's Attachment 17983 Attachment 17984 Attachment 17985
It's pretty frustrating since the more you sand the more white it brings to the surface and even after buffing it stays white. Some of the stuff it's hard to get a picture of since it doesn't like to zoom into the boat if it's not sanded. In the beginning, when I first saw these spots, I would dremel out the white and fill in with black spectrum gelcoat, which I'd sand down and then get a white ring around the repair. I'm not sure if there's more pictures lying around but I'll try to find some. This is pretty small stuff but more will probably pop up soon since I sprayed about 3 oz's of gel on to get something I can sand flat and try to blend in, hopefully without sanding through the black again.
Also the first picture shows a spot that used to be about an inch long and quarter of an inch thick that I was working on covering with gel, second photo shows the large area that I'm currently working on that went through in a spot and the third photo shows it buffed, but I don't think I went beyond 600 grit which was to see if I was going through.
Also it doesn't appear to be painted since the Spectrum gel matches pretty well?
To me it looks like you are not using a fine enough sand paper before you switch to compound and polish. I usually work my way up to 2,000 grit before I switch to a compound/polish.
That is how the black gel looks on my Supra after the first pass of wetsanding
I agree. I think you're getting too aggressive with the paper and not working your way up. Start with 600 or 800 and keep bumping up to at least 1500 before you switch to compound. The black will turn blacker and richer with each step. I can guarantee that you're not sanding through the gel coat. And you're making things worse by applying more gel to these areas at this point.
I finally found the pictures that do a better job of showing the white streaks I was talking about. Before I finish I always sand up to 2000 grit before buffing as you guys seem to understand why, but just to check progress at 600 I'll buff it just to make sure everythings coming out evenly. As you can see in the pictures some of it just ends up horribly white and I have no idea what's causing this.
Attachment 17986Attachment 17987Attachment 17987Attachment 17988Attachment 17989Attachment 17990
Only relevant picture in this one is the 4th where you can see, from a previous repair, the part where it was ground down into the white, filled with black and brought back up to the surface...however it shrank down below the surface. Lesson learned
What grit are you starting with? That looks like a lot of scratches for wet sanding.....
Usually 600 since it looked like the top layer of gel was oxidized but sometimes it'll be 1000 if it's on a DA and the surface looks cleanQuote:
Originally Posted by wotan2525
Are you using just water ? Or soap and water and changing paper frequently ? Gel coat is hard reall hard , no way your sanding through , you have started with 600 that still kinda low . I would start at 1000 with 1:1 soap / water in a spray bottle . And wetting every other stroke . Start by hand . Leave the DA alone until you find the paper pattern that's gonna bring up the shine . What polish pad are you using ?
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I can't tell for sure but it looks like somebody used that poli-glow / mop-n-glo stuff on your boat at some point.
The process for compounding that I use for hand sanding is 600 - 800 - 1000 - 2000 if I can but with the DA I'll start at 800 or 1000 depending on the surface using soapy water. The water is usually like 1:30 dish soap/water which I wet it down about every 30~45 seconds to make sure there's nothing on the pad, maybe spraying 15~20 seconds on the DA. Occasionally, if I don't like the surface, I'll compound it early to see if certain marks go away and then go on to the next grit but for finishing it's always at 2000. A lot of the pictures were taken prior to any compounding because once it's compounded the camera won't focus on the finish but I'll upload the compounding job I did on it last year. The majority of the hull looks great, but it's the white streaks that show up under scratches that get bigger when you sand them that's the issue I'm dealing with. You can see it in one of the pictures on the first page where I put some bondo on the hull to help build the surface up, before removing it and ultimately shooting new gelcoat over it a few weeks ago. New gel wasn't thick enough though so some of the white is showing again and I'll probably have to get more gelcoat and respray it which sucks. Nothing enjoyable about spraying gelcoat... Attachment 17996Quote:
Originally Posted by lively
I just searched that stuff and it looks like a mess. Way too easy to be good for gelcoat. You think that's why it looks oxidized in parts? I ask because I've never heard of that stuff before let alone seen it.Quote:
Originally Posted by Wulphie
First let me say that I have never used it on a boat or seen a boat that I was positive it was used on.Quote:
Originally Posted by sailnaked6842
With that said when I would try to wash and compound/wax the black gelcoat on one of my boats I could never get it to buff up, it would look a little blotchy and it just had this look about it like there was a film or layer of something on it. Now I have had prior experience with dark red (nautique) gel that oxidizes badly and I could always get it looking mint so something seemed fishy to me. I did some searching around on the web and that is when I came across some posts about people putting a couple layers of mop-n-glo on their black gel coats to darken up the milky oxidized black color. That is what led me to believe this was done on my black Pirata but I cannot be sure. Either way it was a total shit show. It is possible to sand the crap off but it takes a lot of time because it really clogs up the sand paper. I cannot advise you with certainty because I am not there looking at your boat but I believe you just need to take a whole lot of time wet sanding with plenty of time on each grit. Do not rush from one grit to another. eventually you will be rewarded with a mint looking boat.
Interesting because that's been one of the biggest headaches about this boat! I've sanded my ass off trying to get the color even in areas because, like you said, it would look blotchy. You can clearly see it in some of the pictures where it's been sanded and some parts looked dull, like gelcoat that has been sanded, and the other stuff just looked too shiny and weird. I've put maybe 30 hours into the gelcoat on this boat through various repairs and on the dark grey surface they all look good (if you can find them :wink:) but you can see that the black just never comes out well. I'll keep up with the wet sanding however I'm still trying to figure out what the big white streaks are because it's definitely getting sanded through like if you look at picture 4 at the top of the page, the big white streak above the U, if you sand it then it'll get bigger.
Attachment 17997
Picture of the same spot, post repair, came out like crap since I didn't use any patch aid, only one coat of gel and preval sprayer -> too thick and made pin holes. Will probably end up redoing it.
I agree, I use 800,1500,2000,3000.