Hello , its all black and want to paint the blades only with white.
Is it going to change anything in with the fan like its speed or something
And do i have to sand it and use a primer before painting?
I wouldn't paint the fan blades. They rely on being perfectly balanced so when they spin they do not vibrate. Adding weight (paint) will throw them off balance as you cant ensure you will get an exact even coating on each blade. Reducing performance and probably increasing noise. But it can be done if you're careful!
Most things that rotate rapidly when operating needs to be well balanced. They do it to car tyres also by adding weights around the outside of the rim to keep centre of gravity exactly in the middle. If you have to paint - then paint the shroud.
I wouldn't paint the fan blades. They rely on being perfectly balanced so when they spin they do not vibrate. Adding weight (paint) will throw them off balance as you cant ensure you will get an exact even coating on each blade. Reducing performance and probably increasing noise. But it can be done if you're careful!
Most things that rotate rapidly when operating needs to be well balanced. They do it to car tyres also by adding weights around the outside of the rim to keep centre of gravity exactly in the middle. If you have to paint - then paint the shroud.