I hope this is okay to reblog! I know we aren't mutuals but I thiiiiiiiiiiiiiiiink we're mutuals-in-law? Anyways I saw this and remembered an old trick I saw probably over a decade or so ago in some long lost tutorial which I've been using ever since- So I've done my best to recreate the tutorial, or at least make my own using what I do now-
So to start off we've got our line art, we're assuming for the sake of this tutorial that it's all neatly closed up under those couple layers that are blocked on top of it, make sure you're on the lineart layer. Then we're going to use the "auto-select" tool on the setting "Refer-to-editing-layer-only" (In CSP at least it looks like a little magic wand)
Then we're going to select OUTSIDE of the lineart, now for this to really work well it helps to draw on a large canvas, I tend to draw at 600 dpi and then actually post the images scaled way down at like 300-72 dpi or smth depending.
So when we zoom in it should look something like this, because we've selected the area OUTSIDE of our lineart
then we're gonna go up and click on "expand selected area" and expand it by like ~2 pixels
After that we're gonna go back and click on the option directly Above "Expand selected area"- "Invert selected area"
And then we're going to create a New Layer UNDERNEATH the lineart layer, find some nice light color that contrasts well with whatever the color of our background is, and use the fill tool
Now, obviously that wasn't perfect, there's some issues there with space filled in that shouldn't be and such, but that's a pretty easy fix, just go back to the line art layer repeat the above steps in the areas outside your lineart that were filled in(skipping the inversion) but instead of picking a new color we're going to use whatever the fuck this thing is on the color slider. I do not know if it has a name but it is my best friend and lover
and use the fill tool with that. (Just like be careful to remember to switch back and forth between your lineart layer and your new solid block color layer, and also the expanding the selection by 2 pixels before erasing from the Solid Block Color Layer and NOT your lineart layer. The amount of times I accidentally erase like 2 pixels off my lineart and have to go back and undo that....)
ANYWAYS ONCE THAT'S ALL SET UP we now have this beautiful wonderful solid block of color under our lineart which!!!!! Shouldn't be crackly b/c it should be fairly deep into our lines. And this is my personal favorite part. Everything about digital art got so much better when I learned how to use this shit->LAYER CLIPPING
We're gonna make a new folder above the color block layer, and we're gonna use that little button right there to clip it to the color block layer we just made under our lineart, and now every single layer that we create inside that folder will only be visible over that color block, so you can't color outside the lines. (So if you DO want to color outside the lines, like for effects or for something that doesn't require line art that will need to be it's own layer outside and above the folder)
I hope this is helpful and that it makes sense!