what nodes are used? trying to add a layer of oil on my head mesh and control the shine. i can add a grey scale map on the roughness but dont know how to control its shininess. help?
If roughness = 0, perfect mirror
If roughness = 1, no reflections
If roughness 0 > and > 1, some blend between.
Im aware of how roughness works. Issue is I’m trying to put a roughness map on there but I don’ know how to control the roughness of it. If I connect a v3 grey scale pic to the roughness it works but then how do I control the roughness for wet looking to duller? There has to be a node
Try using a multiplier node. Also with some materials, you can try a 1 into your specular setting
Here a pic. this works, but i no longer can set it between 0 to 1 
I played with the spec … Ill see if i can play with it again. But you see my pic, how can i regain control to set it to glossy or dull?
Ok this node (Blend Difference) seems to have done it. Is this what the node is intended for? Seems to do what I wanted.
Actually no, didnt work. the greyscale map isnt being applied.
Tried playing with the spec. it just brightens the gloss but does not duff it like changing the roughness by itself.
this is what fatalmuffin said to do, but have the multiply node go into roughness. that way its still masked but you control the intensity
hmm… having the multiplier plugged to the spec seems to work though, if i plug it to the roughness… the spec map does not take effect. I think this must be the correct way…
BTW… checked out your Artstation page. pretty neat work!
OK… THIS… finally did what I was exactly looking for. Took me all day to figure it out but here it is. Now I can control the wetness look of the roughness.