Attempting a “black fire” demo, but getting mixed results.
Attempting a “black fire” demo, but getting mixed results.
cross-posted from: https://lemmy.world/post/6405398
So I’m attempting to make a “black flame candle” for a Hocus Pocus movie night this Halloween.
I’m basically going to be filling a spirit lamp with methanol mixed with NaCl and light it under a low pressure sodium vapor light.
The idea is that the sodium ions given off by the flame will perfectly absorb the sodium spectrum given off by the light and appear black.
Early tests showed that this works to a degree. I get a bit of a black rim around the edges of the flame, but it still appears yellow. Any idea why this is happening? The effect appears better the smaller the flame, so it might not be a problem when I get the spirit lamp working (it’s in the mail).
I don’t fully understand this phenomenon, so any explanation is appreciated. Does the brightness of the flame have to be less than the bulb for it to work?
I'm just guessing, but is it possible that the hotter temps at the edge of the flame are the only place where the NaCl is igniting/diffusing? Might need more NaCl, but I'm thinking that you need a more efficient or hotter overall burn.
But these are just some layman's guesses.
I just saw your other post in askchemistry with the grill lighter. I think it's your ratios. Smaller flame with more salt ratio got blacker vs large flame. Try adding as much salt as you can before it stops being flammable. Although I will note that again, the edges seem blackest. Heat could still be an issue.
Maybe it's even too hot and the sodium is becoming a gas and vanishing too fast, not leaving enough behind long enough to make a solid black flame. The small grill lighter probably burns cooler and that might be why.
Again, just ideas.