Hi guys does alloy compounds (blue and brown)for pollishing differ to say stainless or mild steel?Also i have sanded the parts i want to polish with 120 grit paper,do i need to sand with a finer paper or will the sissal get rid off the small scatches.Only ask because magnet mart have a universal kit with brown and white compounds.They say it will do all steels but yet they sell the brown and blue compound seperate which is what the tutorial on google says to use.