gel coat pittin

[pescaloco]

hey there guys,

another gel coat question. Would you think areas of porosity (tiny pits) are the normal result of sun and aging in a gel coat surface or more likely a defect in the original layup/molding process (like it was too hot a mix)

several of the boats I care for have this surface pitting is areas and seems to be mostly of the flat sections with sun exposure, like the cap rail.

so here is the bad part, the pitting is very deep and after wet sanding to the point where it was not safe to go any further some pits still exits.

I guess what I am trying to figure out if this is a maintence issue or a manufacturing issue.

Sorry no pictures, but if you have any thoughts on this please let me know.

thanks Mark

[ondarvr]

The porosity has been there since day one, it's normally from applying gel coat too fast or too thick and this can be a problem in hard to spray areas. There's not much you can do to fix it after the fact, other than sand and respray those areas.

[Herman]

About gelcoat porosity:

Most builders use the same peroxide for both laminating resin and gelcoat. However, for gelcoat there are better peroxides, which greatly reduce porosity.

Other factors which trigger porosity is thinning the gelcoat with acetone. Always use the proper (sprayable) gelcoat, in combination with the right machinery to do so.
If you ever need to thin gelcoat with acetone, make sure you keep enough distance to the object for the acetone to evaporate, and build up thickness slowly, to allow any residual acetone to evaporate before the gelcoat sets.

Applying gelcoat the right thickness is critical as well, both for porosity, barcol hardness, and proper cure.
If you ever see a guy spraying gelcoat without gauging the thickness regularly, he is either a trained expert who knows exactly what he is doing (and failing to do his quality control...)
...or a guy who is not trained for the job. (I see a lot of shop floor managers bitching about the quality of work of their workers, but if I ask about the last time they got proper instructions for the job they are supposed to do, I get no answers...)

[pescaloco]

thanks for the reply.

this stuff is killing me I have been doing some buffing and the dark abrasive media in the 3m super duty compound imbeds in the small pits and it looks like I buffed with dirt as the abrassive. Any way i was able to sand it out.

It suck because these are not old or seriously negelected boats, and they are very expensive fishing boats made over in Tiwaan

thanks for the help
Mark