Gelcoat "microdots" and how to get rid of them

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Author Topic:   Gelcoat "microdots" and how to get rid of them

Buckda posted 04-21-2011 01:45 PM ET (US)
I'm cleaning up the boat, doing some wetsanding and waxing, etc. to get her ready for the season.
This is not a new phenomenon, I'm trying to address it.
The whole boat was rather chalky, but the areas exposed to the sun (topsides) show little, tiny black or grey dots. This boat was neglected by the former owner - and I waxed it last year when I bought her, but didn't go much further to cut the oxidation on the topsides. Now I'm going through and doing some deep cleaning.
I don't want to sand too much of the gelcoat off - and I'm hoping these microdots aren't indication that I have thinned the gelcoat too much...but these dots are present even before I begin sanding.
I've been stepping up the sanding - starting with a course 400 grit, then to 600, 1,000 and 1,500, followed by a polish and wax. The finished area is butter smooth, but the dots remain.
Any suggestions on 1) what these are (and are indicating) and 2) how to make them go away (short of re-shooting the topsides with new gelcoat). ??
Thanks in advance for your help.
Dave
home Aside posted 04-21-2011 01:52 PM ET (US)
I've noticed those before, I had a few on my stern cross beam (if they were in fact the same thing you're talking about) I thought it might have been mildew in my case. I used 409 and a kitchen scrubby to clean the surface, it seems to have worked well.
Pat
Blackduck posted 04-21-2011 02:13 PM ET (US)
Heck, just take a sharp object and scrape down one of the dots to see wether you are down to the laminate or not. Use a magnifier if your eyes are as weak as mine. I wouldn't abrade any more of the gel coat until you make this determination.
Buckda posted 04-21-2011 03:09 PM ET (US)
On further inspection, these are tiny pores in the gelcoat. The wax fills them so they are tiny "white dots" in those areas.
ConB posted 04-21-2011 04:14 PM ET (US)
I have had lots of mildew spots in the gel coat on a couple of old boats. Had to tilex the topsides before I would wax.
Con
Buckda posted 04-21-2011 05:25 PM ET (US)
It is very unlikely that this is mildew. If it is, we're all in trouble because it's tenacious enough to withstand scrubbing, washing, wetsanding and orbital buffing.
God help us.
davej14 posted 04-21-2011 05:32 PM ET (US)
How about this:
http://www.google.com/search?q=artillery+fungus&hl=en&client=firefox-a& hs=T1M&rls=org.mozilla:en-US:official&prmd=ivns&tbm=isch&tbo=u& source=univ&sa=X&ei=SKKwTYDNFMe5tgfNmPj_Cw&ved=0CCwQsAQ&biw=1280&bih=607
http://www.personal.psu.edu/faculty/d/d/ddd2/
davej14 posted 04-21-2011 05:36 PM ET (US)
A better url for artillery fungus, it really is nasty stuff:
http://www.firstchoicepowerwashing.com/artillery_fungus.html
Buckda posted 04-21-2011 06:01 PM ET (US)
Too big. Think angry (but detail-oriented) little elf with a pin and a small hammer.
Tom W Clark posted 04-21-2011 06:05 PM ET (US)
Those are just tiny little bubbles in the gel coat. Time, weather, sunlight UV and washing have exposed them and opened them up.
Sanding more may just make them larger depending on how much of them is exposed now. I wouldn't worry about them too much.
ConB posted 04-21-2011 06:08 PM ET (US)
Try diluted beach on a small spot. If that does not fix it may be the gel coat is now to thin to polish.
Con
Treypescatorie posted 04-21-2011 10:10 PM ET (US)
I concur with the bleach. I get the black specks all the time. I use bleach mixed with laundry soap, also use this solution on the non skid, works great.
pcrussell50 posted 04-22-2011 03:48 AM ET (US)
I'm pretty sure what Dave is talking about is what Tom described, and is not the little mold/mildew specks the rest of us get.
From an old thread, many moons ago, I learned to use Barkeepers Friend for cleaning gelcoat, as its non-abrasive, cheap, and works like crazy. Takes off the mold specks like nobodys business.
-Peter
PeteB88 posted 04-22-2011 04:40 AM ET (US)
Probably barnacle eggs.
Buckda posted 04-22-2011 06:44 PM ET (US)
Thanks Tom. I think that is exactly what I'm describing.
Probably will need to wax more frequently?

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Author	Topic: Gelcoat "microdots" and how to get rid of them
Buckda	posted 04-21-2011 01:45 PM ET (US) I'm cleaning up the boat, doing some wetsanding and waxing, etc. to get her ready for the season. This is not a new phenomenon, I'm trying to address it. The whole boat was rather chalky, but the areas exposed to the sun (topsides) show little, tiny black or grey dots. This boat was neglected by the former owner - and I waxed it last year when I bought her, but didn't go much further to cut the oxidation on the topsides. Now I'm going through and doing some deep cleaning. I don't want to sand too much of the gelcoat off - and I'm hoping these microdots aren't indication that I have thinned the gelcoat too much...but these dots are present even before I begin sanding. I've been stepping up the sanding - starting with a course 400 grit, then to 600, 1,000 and 1,500, followed by a polish and wax. The finished area is butter smooth, but the dots remain. Any suggestions on 1) what these are (and are indicating) and 2) how to make them go away (short of re-shooting the topsides with new gelcoat). ?? Thanks in advance for your help. Dave
home Aside	posted 04-21-2011 01:52 PM ET (US) I've noticed those before, I had a few on my stern cross beam (if they were in fact the same thing you're talking about) I thought it might have been mildew in my case. I used 409 and a kitchen scrubby to clean the surface, it seems to have worked well. Pat
Blackduck	posted 04-21-2011 02:13 PM ET (US) Heck, just take a sharp object and scrape down one of the dots to see wether you are down to the laminate or not. Use a magnifier if your eyes are as weak as mine. I wouldn't abrade any more of the gel coat until you make this determination.
Buckda	posted 04-21-2011 03:09 PM ET (US) On further inspection, these are tiny pores in the gelcoat. The wax fills them so they are tiny "white dots" in those areas.
ConB	posted 04-21-2011 04:14 PM ET (US) I have had lots of mildew spots in the gel coat on a couple of old boats. Had to tilex the topsides before I would wax. Con
Buckda	posted 04-21-2011 05:25 PM ET (US) It is very unlikely that this is mildew. If it is, we're all in trouble because it's tenacious enough to withstand scrubbing, washing, wetsanding and orbital buffing. God help us.
davej14	posted 04-21-2011 05:32 PM ET (US) How about this: http://www.google.com/search?q=artillery+fungus&hl=en&client=firefox-a& hs=T1M&rls=org.mozilla:en-US:official&prmd=ivns&tbm=isch&tbo=u& source=univ&sa=X&ei=SKKwTYDNFMe5tgfNmPj_Cw&ved=0CCwQsAQ&biw=1280&bih=607 http://www.personal.psu.edu/faculty/d/d/ddd2/
davej14	posted 04-21-2011 05:36 PM ET (US) A better url for artillery fungus, it really is nasty stuff: http://www.firstchoicepowerwashing.com/artillery_fungus.html
Buckda	posted 04-21-2011 06:01 PM ET (US) Too big. Think angry (but detail-oriented) little elf with a pin and a small hammer.
Tom W Clark	posted 04-21-2011 06:05 PM ET (US) Those are just tiny little bubbles in the gel coat. Time, weather, sunlight UV and washing have exposed them and opened them up. Sanding more may just make them larger depending on how much of them is exposed now. I wouldn't worry about them too much.
ConB	posted 04-21-2011 06:08 PM ET (US) Try diluted beach on a small spot. If that does not fix it may be the gel coat is now to thin to polish. Con
Treypescatorie	posted 04-21-2011 10:10 PM ET (US) I concur with the bleach. I get the black specks all the time. I use bleach mixed with laundry soap, also use this solution on the non skid, works great.
pcrussell50	posted 04-22-2011 03:48 AM ET (US) I'm pretty sure what Dave is talking about is what Tom described, and is not the little mold/mildew specks the rest of us get. From an old thread, many moons ago, I learned to use Barkeepers Friend for cleaning gelcoat, as its non-abrasive, cheap, and works like crazy. Takes off the mold specks like nobodys business. -Peter
PeteB88	posted 04-22-2011 04:40 AM ET (US) Probably barnacle eggs.
Buckda	posted 04-22-2011 06:44 PM ET (US) Thanks Tom. I think that is exactly what I'm describing. Probably will need to wax more frequently?