complex "gradient" blending by hand

[dawn snow]

I remember in older versions of photoshop, if you wanted to make complex gradient-like effects, you would brush down some solid colors next to eachother, then do something to have them mix in the boundary zone, some kind of blur or smudge or something. I can't find info on it really on google, since search is garbage now

so for example a radial gradient could be produced by putting down some nested circles of varying widths, a linear one would just be a few colors side by side, etc

but you could also create more complex mixes that cant be created in the gradient tool, for instance by placing four squares around a common corner

[reef stream]

You're probably talking about this tool?

"smudge tool" also super useful to blur or blend masks!

You can play with smudging iffrent layers with different blending modes on each layer by ticking that option

also there are a few settings you can play with in the top bar

[dawn snow]

no, i know how to use the smudge tool

it's not that

I'm describing a filter, maybe a gaussian blur or something in liquefy

idk, i was wondering if it rang a bell for anyone, but I could probably figure it out through experimentation

it's a technique I learned in the early 2000s

[reef stream]

noise> median? (throwing things in here)

you also got box blur or surface blur that could do the trick.

I have seen long ago techniques that used the path blur or other type of blurs from the blur gallery and also things that made use of smart objects, the dissolve mode and those type of blurs all together.
I thinking about that type of things
https://www.youtube.com/watch?v=Itmn1ZUYWlg
or
https://www.youtube.com/watch?v=Y31txZYxeE4
Not sure that's what you are looking for, but maybe it will give you ideas