I don’t sketch with brush pens often,
because I like a juicy wash and/or pen and ink — BUT I do occasionally, and so, here is my take on them. They are great on the go for quick sketches, thinking sketches.
*But then so is a fountain pen… * 
I use them to add a bit of color (see waterbrushes filled with liquid watercolor
or ink, below) when you can’t pull out your watercolors at all — not even with waterbrushes!  As in, on the sly, like sneaking candy into the movies.

I wrote a critique of my favorite waterbrushes when I was using them all the time.  Bottom line, I still prefer Pentel Aquash because their point stays pointy longer.  The downside is they don’t hold much water.  Upside is they are a bit shorter, hold a point, and will fit into a small pack.  And they are easy to refill!

When capping brush pens, be careful about the brush filaments
lining up as you put your brushes away.  I store waterbrushes filled
with water cap-less unless traveling; they stay fresher.

I’ve filled several with liquid watercolors (here I am using the last of my
discontinued Luma liquid watercolors), and pop them into my purse in a plastic bag (leaks?? aaack!)  Before I fill them with anything staining, I test them because many Pentels leak!  And yes, you can fill them with INK!  Yay!

Make sure you are using liquid watercolors and nto liquid acrylics, which will clog.  Finally, cap carefully as bits of watercolor or ink can spray.

A note about ink dilution.
I use distilled water to dilute my inks when
I am painting, but am uncomfortable
putting them into a waterbrush as they go bad
(inks smell when they go bad, fortunately).
I have De Atramentis Dilution Liquid
for Document Inks in my cart.  I want to
try it in my waterbrushes to see if the
ink stays fresh longer.  And report, of course.

I like making my own colored pens because they
are refillable, so less landfill issues.  Every little bit helps.

Jetpens, has four of various sizes for $24.50 (free shipping at $25.)
I do not recommend the one filled with black ink, because it is a pale black, though waterproof (see below).  And while I like to support my favorite stores, but I sometimes find a bundle on Amazon and use it to top off an order for free shipping.
I’d rather spend the $$$ on supplies than shipping!

What about manufacturer’s inked brush pens?

We discussed the Pentel filled with black ink, above.

The pre-inked pen I use the most is the Platinum Japanese Art Pocket Brush Pen.
*It is not an actual brush pen but a felt tip; why do they call it brush tip?*
I drew the piece above with it and added watercolor, nice, easy drawing!  I buy them again and again, and keep one in my purse.  They are pretty.  Nice point, though the point does wear down, eventually, unfortunately, and then off to the landfill.  This bothers me.

MANY artists swear by the Kuretake Zig Cartoonist Brush Pen No. 22.
It worked nicely for the image above but I don’t like them.
I’ve bought three of the same brush pens from Jetpens, two of which are shown below.
The one on top and the middle below, are the same pen,
bought at different times from JetPens, which says they are water-resistant.
One is clearly not water-resistant, and the other is.  Both say 22 on them, one in Japanese.  The quality of the ink is inconsistent!  It drives me crazy to not know what I am buying, however, if you don’t care about waterproof, then it makes no difference.

Lastly, while we are talking about landfills and reusable pens, while not perfect, Preppy is making two more pens I love and give away, though I rarely use sketching.

Preppy makes a refillable eye dropper highlighter!!!!  Yay!  I now have ONE highlighter,  and no more landfill.  The ink above is  Noodler’s Firefly Ink.
I highly recommend the 4.5 oz Bottle with the eyedropper for this application!

Preppy also makes a refillable eyedropper felt tip pen.  I wish it was a finer tip, which is why I haven’t bought more.  I can fill them with my favorite inks (these are DeAtramentis Documents inks)!  You can, of course, use their cartridges — but seems to defeat the purpose for me.  I make them both eyedropper pens.
Goulet sells them too.  See their video on eyedropper conversion below.

©D. Katie Powell.
My images/blog posts may be reposted; please link back  to dkatiepowellart.