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the Stencil function ignores layer opacity when you use CLR.

it will always CLR through the stencil at 100% no matter what layer opacity you have set.

if you want the CLR working at the layer percentage, you can only do that by merging it, using blendmode erase.
This requires a few more steps but its also not logic to me.
Isn't it logic that when you set a layer as a stencil,
that you control its strength (opacity) by the opacity slider?



image: mask is set to 50% but it Clears at 100%
but when you merge with blendmode erase....: then it does work:

I want to point out that I like to use the stencil with its source layer set to some transparency, or even 0%. If I want to clear something to 50% with a stencil, I use a rectangle fill set to 50% opacity at erase.

good point. Thanks!

the biggest problem with stencils and masks in tvpaint is finding the simplest way of getting the result you need.
Because there always is more then one.

True, and some workflows are not really intuitive. I've found my own solutions so I can work pretty fast in TVP. Stencils are one of its main advantages, I've developed a whole background style around them (starting from writings by John Krikfalusi about Art Lozzi's work for Flintstones).