And I also set the drop down option next to channel name to L8. I'm not sure if it really matters. I just did it like that because Mr. Smith did it so(Actually I'm not familiar with such technical terms. I'm learning little by little).
Speaking of the usage of custom channel in SP, it seems that I still need to work with it no matter how my project policy would be. I mean even though my project doesn't need me to export the custom channels out to the game engine, I think using custom channels looks very handy when it comes to combination with mask generator or brushing.
What I couldn't get is of the paint blistering filter, especially the way how I organize the nodes for purpose of conjunction with custom channel in SP. Where should I feed the input node to?
The key question is why do you need a custom channel, what's a custom channel at all or what do you think could be the benefit from it ?
You can't feed mask layers (generators, smart masks etc.) with channel data - there is no technical link between the channel and a mask layer. Afaik the Devs are working on it for future releases - it's a highly requested feature.Try to create a custom channel like "age" as a dedicated custom mask > create a layer mask with a smart mask. The stuff you paint in the channel doesn't affect the layer mask or vise versa!
You can't create own mask channels to paint over layer masks, because the default shader doesn't know, that you want a filter with a custom cutout mask in particular.
So, why would you waste a lot of time to create a filter, if the creation of a material is much easier?
Why would you create a mask exporting pipeline (filter) for unreal, if you don't need a exporting mask pipeline at all?
That's why I said the presentation is a bit misleading.
You can achieve the "blister effect" with a material (substance), you don't need a (complicated) filter for that. You can find examples here in the forum.
P.S: The "heat" filter affects the base color channel (gets blended), because the "base color" is part of SP's default shader, so it also can be used for general purposes.