The discussion about Isopropyl versus Isopropynal:

Ethanol is in essence a fast drying solvent. Alcohol does the cleaning well. BUT,70% Isoprpyl (rubbing alcohol) has lots of water content proportionally; is is about 1\3 water. Water that is distilled will take quite a while to dry, and I use 90% or better Isopropyl alcohol simply dues to the lower water content in the alcohol mix. It dries a lot faster with less H2O molecule content.You can add a small proportion of ethanol to 90% or better Isopropyl and you will not get a volatile reaction, but you then need good ventilation, as purified Ethanol is a poison. Isopropyl of 90% or better alcohol content works real well astually.

The only thing that could be better is to polish the area of the Heat Sink that contacts the CPU die itself with 1000 to 1500 grit Wet\Dry Silicon Carbide sandpaper in order to in essence LAP the working\conductive face of the Heat Sink and get all the tiny remaining amounts of old HS compound off of the surface of the HS that contacts the CPU core\die. This also works to remove any tiny scratches on contact surface of HS.

Same lapping process that works for desktop HSs works for laptop HSs and the BASIC procedure given here is good to follow with desktop Heat Sinks except for CPU removal which is close to toolless in ZIF desktop CPU socket. I say close to toolless rather than totally toolless since the swinging end of the lever on the ZIF socket release lever has to be released from its locking tang (I use the very tip of a jewelers straight screwdriver to unlatch the lever, myself).