Photographing Coloured Flame KCl

[ArtEO]

Hello everyone,

I’m not a chemist at all, I studied physics which entailed a fair amount of chemistry in the learning but that was five lives ago. Nowadays I m a photographer, mostly editorial portraits but also fine arts. For my latest project I take pictures of a wide range of phenomena on very different scales, some calling for imagination, some being „cold“ descriptive.
I came across a YouTube video of someone burning a sheet of newspaper „soaked with KCl“ which then slowly burns in a stunning creeping violet flame.
I’d like very much to take closeups of this phenomenon but am very unsuccessful with my attempts so far.
I have a safe environment at hands, where I first tried to dilute KCl salt in water, soak the paper, dry it and burn it… got my regular orange flame.

I tried with alcohol (hand disinfectant) and salt again…. Same….

Please find the reference video here:


As I’m running out of ideas I wondered if someone could help me on that one. I tried to contact the person who posted the video but it’s dated 15 years ago. Thanks in advance

 

[Borek]

Sodium is present everywhere, very difficult to avoid it. Could be what you use as KCl already contains enough to color the flame.

Two things to do: looks for a source of sodium free KCl (chemical suppliers, they always sell reagents with different purities, the purer the more expensive, I have no direct experience to tell what level of purity you need though) and use distilled water.

 

[Rive]

I tried with alcohol (hand disinfectant) and salt again…. Same….

Check if the flame of that 'alcohol' in itself is colourless or orange. If it's orange then there are some additives in it and you need to change to 'clean' alcohol first to achieve some colourless flame.


To be honest, gas would be better since burning alcohol can be really dangerous.
Especially when it's colourless.



Then you can try your salt to see if it's clean enough in itself or not.
The paper can be tricky too, since some papers can contain additives, for example like Ca for whitening (yeah, it produces orange-ish flame )

 

[DrDu]

Most salts are better soluble in methanol than in ethanol. So I would try this. Sodium from the paper will be a problem, too. Maybe the one who made the video used a neodymium glas filter or the like to get rid of the yellow sodium light?

 

[ArtEO]

Thanks for all the answers above ! Im actually ok having a bit of orange flame appearing in the visual mix but what is really at stake for me here is the ‘slow burn ‘ effect one can see at the end of the video. Based on your recommendation, should I give it a try at mixing the KCl salt in methanol, soaking the paper and let it dry, then burn it? (I mess add n I’ll try anyway but I’d just like to understand the process a bit on the way:) )

 

[ArtEO]

Maybe I can add the following description from the 500g box:

• Formula: KCL
• Purity: 99.1%
• Particle size: Fine
• Food-safe, 0.9% magnesium hydroxide polycarbonate as a Antiback remedy
• Branded Product laborladen. de

 

[berkeman]

Antiback remedy

Antibacterial?

 

[ArtEO]

Antibacterial?

Possibly…

 

[Rive]

what is really at stake for me here is the ‘slow burn ‘ effect one can see at the end of the video. Based on your recommendation, should I give it a try at mixing the KCl salt in methanol, soaking the paper and let it dry, then burn it?

Using clean (distilled?) water would be better. Try using different types of paper: maybe with wool content (security papers).

 

[Tom.G]

• Formula: KCL
• Purity: 99.1%
• Particle size: Fine
• Food-safe, 0.9% magnesium hydroxide polycarbonate as a Antiback remedy
• Branded Product laborladen. de

One ingredient caught my attention.

The magnesium hydroxide polycarbonate is a commonly used flame retardent, which is one of the things you are looking for. Maybe you could add an extra bit of that to your mixture.

That, along with the color filter suggested by @DrDu above, could be the "magic" needed.

https://www.linkedin.com/pulse/5-minutes-understand-magnesium-hydroxide-flame-retardant-leon-liu

[edit: Potassium chloride is used as a water softener salt, so you can purchase it at many hardware stores.

The smoke produced by many of these chemicals can be a serious irritant, especially for people with breathing problems. Wear a protective breathing mask while adding chemicals to the fire, and be mindful of which way the smoke is going.

(from: https://www.wikihow.com/Make-Colored-Fire)
/edit]

Cheers,
Tom

p.s. please keep us updated on your progress, and post your images here.