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finefurn

Mottling of color on Underdog Bottom Paint

7 posts in this topic

I'm having a problem with some or all compatibility of "Total Boat"  products.  I'm in the process of restoring the hull on a 30+ yr old FG silboat.  I sanded off the 3 previous layers of bottom paint, repaired dozens of blisters and dewaxed the entire hull.  I masked off the upper section of the hull and below the waterline and applied 5 coats of "Total Protect" (Gray).  I then masked off what will become the boot strap line.  Below this boot strap mask I applied 2 coats of Underdog Bottom paint (black).  The problem I'm having is the Underdog paint is drying gray.  When wet it is pitch black, but as it dries it becomes a mottled gray.  The first coat dried totally gray, slightly darker than the "Total Protect".  The second coat has become mottled.  The areas on the masking tape that the "Underdog" ran over did dry black.  What's going on?. why did the area over the "Total Protect" dry gray.  The spillage on the can and what is left in the paint tray also dried gray, so I'm not sure its an issue of application.  Drying a dark gray is an issue I could live with, although not what I wanted, but not the mottling.  See the attached pics of what I'm tying to explain,  The lighter gray is the Total Protect, the black is the Underdog over the masking tape and the darker gray is the Underdog over the Total Protect, note the mottling.  The second coat of Underdog was applied about 14 hrs after the first coat, and shop temp was in the low 60's  Please don't tell me I need to sand this mess off and start over.  Is this a paint issue or am I doing something wrong?  

post-401-0-71603800-1456707323_thumb.jpg

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Did you apply the Underdog over the barrier coat when it was thumb tacky or after it totally cured?  Not sure why it is gray in appearance.  Did you mix the paint well before applying?

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The barrier coat was drying very quickly, so I made sure the last coat was tacky, only about 1  hr. after it was applied, any longer and it would go beyond the tacky stage..  Also it had an   " orange peel  " surface texture.  BTW the paint rollers JD supplies with the Barrier coat kit are CRAP.  They come apart when rolling out the finish,  had to pick fuzz balls out of the finish.  When the Underdog was first opened it had the consistently of Jello with about 1/4 " of solvent on the surface.  I used a spiral paint paddle mixing stick on a power drill to mix the paint.  It took several minutes to mix it to a uniform consistency of Ketchup , The first coat dried totally Gray except for where it got on the Masking tape, (No mottling)  again a orange peel texture.  I let it dry overnight and did a quick scuff sand with 80 grit and tack ragged .  The second coat has been curing 3 days now, Tomorrow I'm going to move the stands and apply the Barrier coat and Bottom paint on those areas,  scuff sand the entire hull and a apply a  third coat to see what happens .  Of note is that when the Underdog was reopened for the second coat it had thickened, but a few minutes with the mixing paddle on the drill and it was back to looking like Ketchup .  Possible the pain is too thick?  What would be an appropriate solvent to thin ?  

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That does sound to be a little too thick, thin with TotalBoat Special Brushing Thinner 100 should help a lot.  I agree with the roller comment, I like a epoxy foam roller for the primer which will lay down smoother.  

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Thanks Rick

  I just ordered up some of the Brushing thinner.  Any recomendations on the consistancy I'm after.  I'm guessing 10 % would be a good stsrting point, but not more than 30 % overall. .

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Yes, 5 to 10% would be a good start, be sure to mix well if it's too thin all the copper will be in the bottom of the roller pan.

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Just a quick follow up on my Bottom paint job. It didn't matter what ratio I mixed the paint too, I still had the mottling.  but if I scuffed the bottom paint after it was thoroughly dry it  evened out the color.  Not a issue when its in the water, who can see the bottom paint anyway,  but on the trailer, maybe for us anal types.

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