[dmm10]

> BUT IT IS WATER BASED. So even a light rain can wreak havoc on my notes.

Water based != water soluble when dry

I would suggest you try similar pens with a different ink. Staedtler Pigment Liner and Sakura Pigma Micron pens (both of which come in 0.3 mm) use water based pigments which are waterproof when dry and archival. They both survive rain quite well in my experience and are used for outlining by some artists who then apply water color paints or other water based media without the dried ink bleeding.

There are also waterproof fountain pen inks. Platinum Carbon and Noodler's Bulletproof Black are two good ones.

For a common counter example to a water based substance being water soluble once dry consider water based exterior latex paint.

[dr_zoidberg]

Will look into them, thanks for the pointer :)

Unfortunately every pen of this kind I've used suffered from being water soluble after dry, so I just assumed all where.