Weight paint causes strange sharp transition

Hello everyone!
I am new to this community and hope to find answers.
I decided to rig a model myself based on some tutorials. The armature works fine I think but when I try to weight paint the bones, a super sharp transition appears between non painted and painted vertices. No matter what I change in the brush/tools options (strength, weight, auto normalize etc) nothing helps and I just cant get a nice smooth transition between bones.
The rig is not very complicated.

Any help would be great!

did you turn off all of the modifiers?

The model has only the armature modifier. Other than that, nothing else.

I have a feeling the sharp transition happens where a vertex with bone weights joins a vertex without any bone weights?

Bone weights can’t be understood out of the context of multiple weights. A vert with weight 0.2, but only weighted to a single bone, may as well be weighted 1.0. You can’t see the transitions until you actually weight a vertex to more than one bone.

Ah! Interesting. Indeed, I erased all vertex weights to completely paint them from scratch one bone after the other. So you mean because other bones in the chain like the spine or rib bones don’t have any weights applied to them, it causes this result?

Yes, don’t expect to be able to see various weights when you only have a single weight assigned.

Thank you so much! It worked! I can finally go to bed in peace :smiley: