Logo Etching Questions - Lectroetch

[rockhound]

I am new to etching and could use a little help. I have the Lectroetch Model 6A pictured below. It has a range of 0 - 26V with a variable control knob (0 - 100). I purchased my stencils from Ernie at Blue Lightning and they look great. Ernie is a great guy, I watched his vid on how to etch and tried his steps. I'm not quite getting the results I want and am hoping I can get some advice here. I've only attempted three etches, they are all similar.
Problem: Etch is not turning black throughout.
I'm doing as Ernie said, 3 intervals of 5 seconds on about 14V DC (guessing by the dial percentage)... then repeat while switched to AC. He was using a different steel however and it was heat treated.
The steel I'm experimenting on is CPM154, not heat-treated. Not sure if hardness plays a role in this at all. It has a 400 grit finish.
Should I crank it up higher for this type of steel?
or....
Hold the pad down for longer, or more intervals during the AC phase?
Any help VERY much appreciated!

2018-05-18_01-56-45 by Chris Evenstad, on Flickr

2018-05-18_01-57-19 by Chris Evenstad, on Flickr