OK. This is probably something I’ve done, but I can’t see what. I’m fairly new to Blender.
I’m weight painting a simple arrangement of three hydraulic pistons, They are part of
a much larger model, and so far I’ve done exactly the same procedure at least two
other places on the same model.
But on my third attempt the weight painting is no longer working.
- As I go into ‘Weight Paint’ mode the mesh turns black when I expected blue.
(see attached )
- But if I hit ‘f’, I get a blue color as expected 
- But then if I start to paint, the mesh appears to turn itself inside out!
[see 4 - only a few vertices painted here]
Can anyone tell me where I’ve screwed up! I’ve checked the normals. they look
OK. I’ve also made sure to clear all other vertex groups (if any) from the mesh I’m
painting. Is there some clue to be had from that black color?
Thanks in advance. G.