Can I subtract a vector brush stroke from another curve?

[Ade H]

Background info: I use Affinity Designer to make vinyl masks (for airbrushing) via a Cricut vutter. I'm used to placing my design over a rectangle (with all objects converted to curves) and using the subtract button to turn it into a mask. Then it goes off to the Cricut app. 

Now, I need to make a mask which looks like a hand-painted patch repair (like you see on boat hulls, etc.) Imagine a square of paint, opaque, but with uneven edges and a few brush strokes just showing on the edges. 


But how can I paint/draw my patch and subtract it from a rectangle below?

I have tried using the vector brush with a basic "acrylic" brush type, creating my strokes, selecting all relevant objects, and clicking the subtract button. Just as I usually do. But it does not work and I cannot really put into words  how or why it is not working, so I will try to upload some examples.

I have attached (if it works) an illustration of what I am used to doing (top part) and what I want to do (bottom part). Just imagine the white patch to be transparent. The second image shows a design before and after subtraction.
 

Edited August 18, 2021 by Ade H
Added 2nd example

[NotMyFault]

A vector brush does not result in a real vector object, It uses a bitmap for the brush aligned to a vector path.

If you use a real vector tool like vector shapes, pen tool, text etc it will work.

So you may try creating the patch shape on you own using the pen tool.

 

[Ade H]

Thank you. I must say, in case Serif happens to read this, that calling them curves in the layer area is not helpful if it's not really true. 

[gentleclockdivider]

Wel the path is a curve , the brush itself is not 
But I agree with you , they should not advertise them as vector brushes