Below the water line Q-cell?

[Whale1]

Hi just a question, iv just recently glassed on a live bait tank onto a pollyester hull. Ive glassed it on with polly. Im just wanting to know if i can use Q-cell as a filler to fair out the tape. Is Q-cell ok to use under the water line?

[AroMarine]

Q-cell and poly not a great choice below waterline. If you must use it an epoxy barrier coat will offer decent protection.

[AA Fibreglass]

You could use Aerosil as your filler under the waterline.

[kach22i]

FYI:

Descriptions of other "fillers" .......................
(3M Glass Bubbles - Q-Cells - Aerosil - Cab-O-Sil - Phenolic Microballoons):
http://www.shopmaninc.com/fillers.html

I can't tell from the site when, where and how to best use the products. Anyone want to chime in?

Thanks for the tips on Aerosil, that's a new one to me.

[AroMarine]

Qcell, Microballoons, glass bubbles are fillers that are hollow spheres which makes them good for sanding and absorbing water therefore not a great choice under waterline. Polyester resins do not have the water resistant properties to seal and protect these from water intrusion. Epoxy is a much better choice. Cab-o-sil and Aerosil are fumed silica and create dense hard (hard to sand) puttys but are much more water resistant. Any polyester work below the waterline should be sealed with epoxy or gelcoat especially if it is structural.

[kach22i]

Cab-o-sil and Aerosil are fumed silica and create dense hard (hard to sand) puttys but are much more water resistant.
When sanding do you need to use a respirator, or will a paper mask with rubber band do?

[AroMarine]

By the book probably a respirator but once every thing is cured it is fairly inert so good paper masks are ok. Some of the reading I have done seems say that the fumed silicas are not good to breath while mixing so I at least try to be down wind when mixing any of the fillers.