Head Gasket surface

[99XLT-Explorer]

how clean should my head gasket surface be? heres some pics of how clean ive got it so far with a 3m pad and acetone.

 

[96ex5.0]

I like to get them as clean as possible otherwise there is more of a risk for a leak. I use a 90* air grinder with a red scotch bright like pad on it.

 

[99XLT-Explorer]

i got it clean enough i believe the heads are perfectly cleaned and the block you can barely feel the remaining gasket material so i wont be worried about it.i would have used a 3m pad on a air grinder but the block is decently so so i didnt want to risk scoring or making the surface unlevel. as well as throw alot of trash into the motor.