Hello, I would recommend purchasing from wolfbite from airwolf. It is a special formula for plastics to stick directly to the bed.

http://airwolf3d.com/shop/wolfbite-p...s-from-warping

I have been using this stuff for a little bit and it beats the hairspay/glue stick/kapton tape methods by a long shot.

When the bed warms up, this activates the "stickiness" of the solution and when the bed cools down, this deactivates it. Too much though will cause the part to stay stuck even on a cool down. The solution is water soluble. Hearing a cracking noise is normal. This is the part the is being released from the bed.