lasers and flammable dust

[StridAst]

Curious, if one was to spread a SMALL amount of darker colored flammable/combustible powder into the air, i.e. cocoa powder, copier toner (not certain as to copier tonar's flammability, however I assume it's mostly carbon so it stands to reason that it should burn) I wonder if the powder igniting in the laser beam would be visible or not. Granted a large amount of powder in the air would ignite and spread, and fireball, so a larger amount would be rather dangerous. Just curious if anyone has tried anything like this. Probably 2 weeks out or so from ordering either parts or a whole module for my first higher powered laser, so I can't yet experiment or test.

StridAst

 

[Asherz]

I don't know, but I swear I herd of a C02 laser being so powerful it started to Ionise the air around it.

I cannot confirm that is in any case true

I don't know if this powder thing would work though, it may with a 1W+ laser but I don't think the surface area of a powder particle is big enough to absorb enough of the laser light to ignite, maybe if you could focus it that small it may.

 

[Jaseth]

Actually I seem to remember that being a 40W green monster which did something to the air.. IIRC it was on one of andy_con's photo collections of a laser meet. It belonged to laser_man..
This was a long time ago so I don't know if I remember it correctly, but the pictures were great!

Anyway, as Asherz said, the laser would have to be very powerful and only flakes which fell in the tiny focused part of the beam would ignite. And.. it would be very dangerous.

Seb

 

[Flaminpyro]

That is called a fuel air explosion and I have performed this dangerious performance many times in my profesional career on stage and off. I don't think a laser of hand held power has enough power to create enough heat to cause combustion in a typical combustable material. now if you were to use something like black powder dust and blew that into the air of course in very SMALL amounts and trained 200-300mw of BR and prob even IR @500mw into it you could stand a prety good chance of getting ignition.

 

[StridAst]

Yep, when you have enough dust igniting for a self sustained reaction it's definitely a fuel air explosion (therefore likely bad for you, given your close proximity to the fireball). Interesting on the need for particularly explosive substance like black powder to ignite, but the excess heat of black powder would almost certainly ignite the rest of the cloud, giving an explosion rather then a firey looking beam :yabbem: idea was for visual effect, not explosions. (explosions would be quite easy)

Been considering many visual effects I plan on trying with my first laser :evil: First and foremost will be flash paper. I have an old desk, I plan on burning a small hole into, then setting the flash paper on top, (after writing something with a sharpie) After reading the thread on flash paper, I figure it will work quite nicely. Flash cotton will be going in the hole underneath, to add to the fireball. And a little bit of boric acid sprinkled on the flash paper. (it's a white powder, so it shouldn't be too obvious on white paper, and will color the flame green)

Next step: Invite my brother over to see this, which will probably be the first time he has even heard of a higher powered hand held laser, let alone seen one in action... Aim at the black writing on the flash paper, and poof. light, fireball, and no more paper, just a charred hole in the desk I figure his jaw will need to be picked up off the floor...

Granted this will involve doing some intentional damage to the desk, but it should be very much worth the effort, and I need a new desk anyways, as this one is falling apart :evil: Also a green fireball might not be the best without a green laser, however I have a lot of boric acid...

StridAst

 

[Flaminpyro]

Yep here we go running around destroying private property with your laser your going to get us all banned :crackup:

Yep, when you have enough dust igniting for a self sustained reaction it's definitely a fuel air explosion (therefore likely bad for you, given your close proximity to the fireball). Interesting on the need for particularly explosive substance like black powder to ignite, but the excess heat of black powder would almost certainly ignite the rest of the cloud, giving an explosion rather then a firey looking beam :yabbem: idea was for visual effect, not explosions. (explosions would be quite easy)

Been considering many visual effects I plan on trying with my first laser :evil: First and foremost will be flash paper. I have an old desk, I plan on burning a small hole into, then setting the flash paper on top, (after writing something with a sharpie) After reading the thread on flash paper, I figure it will work quite nicely. Flash cotton will be going in the hole underneath, to add to the fireball. And a little bit of boric acid sprinkled on the flash paper. (it's a white powder, so it shouldn't be too obvious on white paper, and will color the flame green)

Next step: Invite my brother over to see this, which will probably be the first time he has even heard of a higher powered hand held laser, let alone seen one in action... Aim at the black writing on the flash paper, and poof. light, fireball, and no more paper, just a charred hole in the desk I figure his jaw will need to be picked up off the floor...

Granted this will involve doing some intentional damage to the desk, but it should be very much worth the effort, and I need a new desk anyways, as this one is falling apart :evil: Also a green fireball might not be the best without a green laser, however I have a lot of boric acid...

StridAst

 

[billg519]

When you do this, make sure to have a video camera off to the side somewhere to record your brother's intro to lasers ...

 

[Asherz]

This is a sure way to loose your eye brows and most of your fringe

 

[StridAst]

I will make a point to record this particular event As for the losing eyebrows, I have used both flash paper and flash cotton for quite a few years. I am quite experienced in how much is "enough" and how much is too much. It makes a nice flash, and startles someone, but does little to burn anything unless you really use a huge amount. A little bit really does go a long way. :evil:

StridAst