How to prevent Gelcoat stains?

DeepBlue2010

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Aug 19, 2010
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I have been dealing with gelcoat stains as a fact of boating life. I Oxalic the heck out of the bottom of my hull to make it nice an shiny only to have it brown and stained couple of weeks later.
Early this season, I had a chip on the hull in the bottom area. I prepped it and sprayed with gel but the season started and I did not have a chance to finish it (fairing, sanding , buffing and polishing). Few days ago when I was looking at it, I noticed that this area specifically is not stained and it stand bright even though all the surroundings are stained brown. It lasted the whole season. I have been reactively treating them but obviously, there is a way to proactively prevent them. I think!

I can only assume it is the wax in the gel. But I am not sure this is the case because I tried to apply wax after Oxalic acid and I still got stains so I stopped since it is too much work to wax the whole bottom for nothing.
Is it really the wax that protects the hull from staining? If so, what is the correct wax to use? I can’t remember which one I used since I have so many different waxes (mold release, UV protection, etc)

Also, if any of our local experts, ondarvr , can shed some light on the nature of these brown stains, it would be greatly appreciated. I am curious to know thier nature. Are they organic organisims? Are they local to Buget Sound area or it is common to all waters?
 
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Woodonglass

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Dec 29, 2009
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Hey DB, I've never owned an Ocean going boat and I DIDN"T sleep at a Holiday Inn Express last night, BUT, have you ever tried this stuff on the tannin stains...
MaryKate_On_Off-2.jpg




Then finish it off with this...
file_30_25.jpg
 
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DeepBlue2010

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So, this wasn't you in Holiday Inn downtown Seattle last night with this short skirted, large breasted girl?! :thumb::lol:

I have solution for the stains when they develop Woody. Oxalic acid does a fascinating job cleaning all stains out and it is very cheap comparing to any other solutions. I just want to prevent them from happening in the first place or at least extend the time between applying oxalic to the best of my ability.

I looked up the 303 and it has good reputation and reviews specially with marine grade vinyl. Not sure if it will close the bores in the gelcoat on the bottom though. I guess I can try it and see.

Thanks for your help. Much appreciate
 
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Woodonglass

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Dec 29, 2009
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Yeah, anything with Oxyalic Acid works really good on Gelcoat stains.!! I used that 303 on my Vinyl and it's GREAT. My boat's painted so I don't know how it works on Gelcoat but if it works as well on Gelcoat it oughta be GREAT as well!!! :thumb:

As far as those pictures of me in the Parking lot with Dolly...That was another guy named Woody!!!!:stupid:
 
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alldodge

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I don't know how to keep them off, but since the stains only show up on old Gel, this makes me think it might just be the old Gel. The Gel wasn't done correctly so may have to live with it unless a redo is planned. Since you linked ondarvr in your first post, he should know if he has time to look. Other then that you could post in the OSO forum and look for GlassDave comments.

Only other way I know to help is paint the Gel with clear Imron like Formula does
 

ahmincha

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Jul 21, 2012
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Is there any possibility that the Oxyalic Acid is causing the staining by actually opening the pours so to speak
 

ondarvr

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Apr 6, 2005
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Staining is a tough one, there are so many possible things in the water that could stain the gel coat it would be almost impossible to list them.

On a new gel coat surface there is a resin rich layer that gives a very good gloss and helps prevent staining, as this resin rich layer is worn or buffed away it starts to expose the pigments and fillers, these items don't hold a gloss as well, plus can more easliy be stained. The speed at which the resin rich layer wears away, or how well the underlying pigments and fillers resist staining is hard to determine, just too many things come into play, One of the critical factors is how well the gel coat was applied. A mediocre gel coat applied well will outlast an exellent product applied poorly.

You could try something like Polyglow, this would give you a clear protective layer between the water and gel coat, I've never tried it, but a product like that could work. There may be other downsides to using a product like it, but it might be worth a try. I've used clear 2 part paints that are pricy, but protect the surface from staining as bad.
 
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dingbat

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Nov 20, 2001
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15,417
The most likely cause of your stain is tannin. Comes from rotting vegetation in the water. We have it really bad in the early Spring then dissipates.

No getting around it. No magic bullets. I pull my boat at the end of the Spring Trophy season and spray it down with oxalic acid and put it back in the water for the summer.
 
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