You will all have seen pictures of people deadlifting with white powder on their thighs.
This is not chalk and I cant stress this enough do not put chalk on your thighs it does the complete opposite of what you want - it increases friction.
What it is is talcum powder or baby powder.
Talc significantly reduces friction when the bar hits your legs allowing a smother lift, it reduces hitching.
The bar wont stick to your skin as you lift and it will maximise your lift.
Use it on the front of your thighs in conventional deadlifts and more to the inside for sumo deadlifts.
In other words put it where the bar hits.
Do not just use talc at competitions get used to using it and refining your technique to get the most out of your pulls.
There is a problem with talcum powder in that it does create a bit of a mess when applying. It is very easy to get it on the soles of your feet, causing slipping. It is also easy to get on your hands which can cause you to lose grip.
Use Deadlift slick no mess liquid talcum powder easy to apply and NO MESS