Quality cocaine is highly hygroscopic, meaning it absorbs moisture from the air. This is why it clumps up instead of always being a fine powder... good cocaine will never come in powder form.

The idea behind hot plating is that the heat will evaporate the moisture. Cocaine has a melting point of roughly 100°C / 210°F so basically if you can still hold the plate it's perfectly fine. I've personally always put the plate in the microwave for ~2 minutes until it's properly hot. (Heating time may vary)

Once the plate is nice and hot, dump the whole bag on to it. Place something flat over the coke (a CLEAN credit card or side of a lighter is ideal) Press down with light pressure and rub in small circular motions for half a minute or so... It'll rub down to the loveliest fluffiest white powder! Follow this up with a fine razoring if necessary.

Properly prepped blow is way kinder on the nose, and the greater surface area to volume ratio means it'll absorb better and work more effectively.

Remember to microwave just the plate, not the cocaine as well.

^{[Shoutout to u/ccncwby whom I borrowed this write-up from and slightly edited]}