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>   (8) For those reasons, I much favour a fullface mask with a rebreather. To
> avoid dead space and in case it breaks, fullface masks often have a mouthpiece
> or a small mouth-and-nose mask inside. (A strapped-on fullface mask with a
> mouthpiece inside can be a remarkably efficient gag (= un-loseable device to
> prevent talking)!) Fullface masks seem to be far easier to keep watertight:
> details of face shape and even being one day unshaven can be very critical on
> watertightness of mouth-&-nose masks. (Some industrial fullface masks are
> unsuitable for underwater use: they seal with a wide sealed thin-walled rubber
> tube filled with air at atmospheric pressure; this moulds to the face, but at
> depth pressure it collapses and so the seal does not work.)

We've intermittently used Scubapro FFM's with the rebreather (to use comm 
gear which, incidently, works superbly with a rebreather).  The SP is a 
"half-mask", sealed in two compartment by a dam beneath thye nose.  The 
part with your eyes and nose is a separate chamber from the part with 
your mouth.  These worked sorta OK (except they're damn uncomfortable 
when we make the straps tight).  I'm not sure how well an AGA or EXO 
(or other mask with an oral-nasal cup) would work, though.  By far the 
easiest way to dump excess gas from the loop with a normal mask or 
half-mask is to simply exhlae through the nose.  If the nose and mouth 
are in the same chamber, you'd have to do some other action (likely 
involving at least one hand) to dump excess gas.

>   P.S. (c) For habitual sea divers, I recommend a good l-o-n-g freshwater dive
> once in a while, as a way to give your kit a good long soak to get salt out,
> especially if your bathroom bath is not big enough or not free for long enough
> at a stretch for adequate kit soaking.

I have a 200 gallon vat filled with freshwater (easily flushable if the 
salinity starts to become measurable) that I soak my gear in.

Aloha,
Rich

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