This might be a well-known problem, or it may just be happening to me. =P
When I select a ztool, say the cube for instance, and then make it a polymesh and divide it, for some reason I get holes on each side. Is this normal? Is there a fix?
it’s a display issue…
and yes, there is a fix.
don’t put a pole in your mesh with move than 5 to 6 edges.
quads for the win.
I didn’t put any holes in my mesh to begin with. The hole appeared from dividing the mesh.
Screenshots, man! Screenshots. There are many different types of holes in ZBrush. Some are normal some are not.
not a “hole” a “POLE” with a P.
Dude the title says “holes” the first post says “holes”, “holes” man , “holes”. 
Not to derail but yes “poles” are to be avoided.
But to elaborate on the topic of the thread at hand, holes get created in meshes when geometry is not properly constructed, like separated faces, when these are subdivided with a smooth algorithm then the holes become apparent when they are “ripped” open.
the problem he is speaking of comes from primitive or startup 3d meshes inside Zbrush…which have Poles.
But yes, to get a hole in the mesh, having split geometry will create them. Also having extreme poles which the default primitives have will create the illusion of them.
Anyway…to avoid that, don’t use the startup 3d meshes that have holes. Instead go to
tool>load>
inside the default zbrush directory there are ztools called “PolyCube” and “polySphere”.
Both of those objects are what I start with if I just want a ball of “clay” to work on. Neither of them have poles that will create the holes you’re talking about.
I hope that helps out.
Ahhh, not a true hole but a “display-bug” issue. In that case I would say definitely stay away from the primitives, or you can just ignore the display-bug issue. I rarely use primitives, but I do recall the fuzzy spot at the poles.