When making a strop, which side to use, the slick side or rough side? This will be used in conjunction with some chromium oxide compound, not the paste kind.
Generally you want to use the slick side. But thats for the regular tan leather. The red/russian/compressed variety is best left for a plain leather strop.
Work it in real good with the heel of your hand. If it is oil based, you can dilute it with a bit of mineral oil to help thin it out. Water based, use water. Don't dilute the paste too thin though.