Hi NNenov,
Yes there are many parameters, and after each adjustment you should do a little test render, or have the Interactive Render Region open (opt/alt + R). So you will see what influences what, anything else will blur your learning experience.
As you wrote there are hundreds of parameter, and while learning, it is not a good idea to do more than one step and without checking what happen. Yes, I know, sometimes problems show up later. Hence the Auto save should be enabled to compare different states.
I’m not certain if Material Hierarchies are at all suggested nor if one should avoid those. I would avoid them. It seems more appropriate to add them to one object directly.
If you use Multiply for example, the top Material should be set to it, not the lower part. It might not matter in most cases, but to have a clean set up doesn’t hurt.
File
https://www.amazon.com/clouddrive/share/MTWajUWa1NbbNWVWdofzJZ9jtkHE3xOHNvnRYxWVajp?ref_=cd_ph_share_link_copy
Screen-Shot
https://www.amazon.com/clouddrive/share/Yz119bJSSW5XosIzY8cIoNz1Uy3L9ierqZkvYWA2HW4?ref_=cd_ph_share_link_copy
Set the black material now to Blend: Multiplied to see the difference.
Screen-Shot
https://www.amazon.com/clouddrive/share/K1xzi22CWhF0EGv3mDtDO3uqbOrX6ouxw9BwM77NkhR?ref_=cd_ph_share_link_copy
Not that clean, a composite would be nicer.
I tried also to multiply the transparent over the opaque, which results in new problems. But just to be a little bit more complete:
https://www.amazon.com/clouddrive/share/HpfepQrpMnXMri6b0cal0D0m65z1blijXOnD7FNhF2X?ref_=cd_ph_share_link_copy
If nothing works to your liking: My suggestion, render the black lines with a white Shading/Background and mix it later in post.
To get clear what is working or not, the first step would be to enable or switch each material. IF this isn’t helping, create a new material and replace it within the Tag. One by one. Leave this material on default.
Materials in SnT have a Priority (Main Channel), that might or might not help, based on the set up.
Problems will always occur while experimenting, so exclude parts, compare, exclude the others. Etc. RMC to get the manual what some parameters do is certainly advised. Otherwise some conclusions might stuck and limit your development.
All the best
Post is updated Sun:03:03pm PCT