Step 12: Final Preparations...
Now, the moment of truth. Release the anchors, keeping one hand on a string at all times. If you're lucky and you kept the weight down (my frame is just under 130g, you can get by with 140g), the whole blimp will slowly rise up. If it does, congratulations! Add some payload to get to your desired buoyancy and take to the skies.
If your blimp fails to rise, do not give up hope. It took me six months to get my blimp fully airborne, you shouldn't feel bad if you don't get it right the first time. Weigh your frame, and do whatever you have to get it 130 grams. If that doesn't do it, your gas is contaminated with air, and you need a fresh run with a better seal between your tube and envelope. Make sure there is no gas leaking from your reaction vessel or tubing.
On an unrelated note, my envelope as seen below is speckled and partially translucent because I spilled some lye solution on it, not because of some error committed by the envelope manufacturer. I'm an idiot. Don't be an idiot.