HAHA! Yea get some of this stuff and seal it all around. Yea, that stuff is abestos, most like it's asbestos tape. YOUR FAMILY WILL DIE! Just kidding. Dont worry, that is too little to do any harm. Just seal it good. Make sure you don't eat it.
Originally Posted by TarheelTerp
And this is duct mastic.
Get some and use it to seal all the joints of your system as well as to encapsulate the white stuff.