Sciencemadness Discussion Board

Colured smoke

NEMO-Chemistry - 12-3-2018 at 11:05

What can i use to make a fairly dense coloured smoke, ideally i want 3 colours, the actual colour dosnt matter but the smoke should be thick.

it should also be pretty safe and able to be passed through a glass tube in a stream (that might be asking too much).

All its for is testing some adapted rotors on a drone, We are trying to see the air patterns created by variously altered props and enclosures, the idea is to find good lift but with as little air disturbance as possible.

one test is simply a 20 foot shed and we will fill it with smoke, then from the outside via a window film it taking off and landing.

We have some other tests but its the smoke i cant figure out! I can make it but its choking!!

aga - 12-3-2018 at 11:38

Heat glycerol.

Vomaturge - 12-3-2018 at 11:56

On the energetic materials side of things, you can use an incense, cigarette, fireworks lighting stick, or other smoldering material for small amounts of smoke, and of course there are pyrotechnic mixes to make bigger clouds of smoke. This one didn't make very much color, and begun flaming at the end. Maybe he could have used less oxidizer?:
https://www.youtube.com/watch?v=4cHJbAIIdQ8
These did better, although it might be hard to replicate the exact ratio of ingredients used, since they were not weighed carefully:
https://www.youtube.com/watch?v=1I2SuS2Z1JM
It seems that some crayons have dyes which evaporate easily, and others don't:
https://www.youtube.com/watch?v=SJe5THzGBZI
In all these cases, I think you could probably take the pan off the heat before adding the potassium nitrate. That might make the process safer. Other than fire hazards, I see two big drawbacks to these homemade smoke generators. For one, you need KNO3. Also, as you have already found out: you can breathe the smoke about as well as you can breathe a crayon.:D

For an indoor test, you might do better with some type of fog machine/vaporizer. I seem to recall that fog fluid is propylene glycol or glycerol mixed with water, and heated with an electric element. Or, if you're willing to spend the money, you can buy one:
https://www.amazon.com/dp/B01MDNTD7A/ref=sspa_dk_detail_0?ps...
But what's the fun in that?


Edit: Of course you can also create a wisp of ammonium chloride particles by combining ammonia and hydrochloric acid vapors. Again, not great to inhale, but okay for producing a little trail of smoke to track airflow. I also wonder if you should really fill the whole shed with smoke, or if just a stream would work better? If the whole thing is smoky, it might be hard to see the air moving once it becomes a homongenous cloud of smoke.



[Edited on 12-3-2018 by Vomaturge]

[Edited on 12-3-2018 by Vomaturge]

Sulaiman - 12-3-2018 at 13:30

https://www.ebay.co.uk/itm/6Colors-Smoke-Cake-Effect-Show-Ro...

NEMO-Chemistry - 12-3-2018 at 13:48

Thanks. those smoke pellets Sulaiman posted look like they will do one the jobs! HCl and electronics not a great mix :D.

Some of the smoke will be pushed as a small stream into the blade enclosure the take off test in the shed is just to see how disrupted the air is, the only way i could think of doing it was several coloured smokes and then taking off and seeing how they mixed.

might not work yet, but worth a try. I still honestly think drones lack decent props, might be wasted effort or might be a way to get better lift from less power.

Smoke Cookie Recipe-

Bert - 12-3-2018 at 13:50

There are not a lot of possibilities for COLORED smoke you would want to breathe.

White is fairly benign done with vaporized "fogger fluid", as is used in concert venues. Lots of other ways to do white, but they all are bad to breathe, varying only in HOW BAD: Like Titanium tetrachloride, Posphorus pentoxide, Zinc chloride... For an amateur without a theatdical fog machine or a lot of chemicals available, a reasonable alternative is:

Smoke Cookies!

For OUTDOOR USE, a cheap long burning white smoke is made by mixing 50:50 by weight of Pottasium nitrate and non dairy coffee creamer powder (yes, the same powder as is used for the 5 gallon bucket sized "Cremora fireballs").

Mix the dry ingredients well, then damp with the minimum ammount of water to make it into something like a stiff cookie dough or Playdough modeling compound. Roll it out into a slab about like you were making biscotti, around 1" thick has worked for me. Cut the slab into "biscotti" about as wide as they are tall, more or less a 1" X 1" cross section, and as long as you made the loaf of cookie dough. With experience, you will know how long these burn, and hopefully tailor the length to your needs. If you want MORE smoke output, you can cut the slabs WIDER. Or just use a whole loaf of dough-

Bake the slabs on a cookie sheet at around 250 F. until completely dry, this takes a while. If you don't get them dry in the center, you may not be able to get them to stay lit, and they will all get damp if kept in a sealed container as that last bit of water wicks out to what FELT like a crunchy dry outer surface. So a long drying time, ideally overnight.

I cook these to dryness in one of those cheap little countertop convection ovens, and OUTDOORS. The fairly low temperature, just enough to boil away the water is to keep the cookies from going off in the oven, but you really don't want to take any chances on these catching fire inside your kitchen. When you smell the smoke, you WILL understand why.

To use, hold a lighter to one end of the cookie, or use a propane torch to get it going faster. Set the cookie on a non flammable surface you do not care about ruining, I like to use leftover ceramic tiles. These need atmospheric O2 to keep burning, don't completely enclose them. They burn a much long time but with a lower smoke output compared to chlorate/lactose/dye smokes the same size.

[Edited on 12-3-2018 by Bert]

NEMO-Chemistry - 12-3-2018 at 14:06

Cheers Bert, might be able to do that outside. I will try and grab some pics when i try it at the weekend, might make sense what i am trying to do.

Bert - 16-3-2018 at 09:18

Quote:
might be a way to get better lift from less power.


Not chemistry, but-

How about DUCTED fans?
Quote:
In some cases, a shrouded rotor can be 94% more efficient than an open rotor. The improved performance is mainly because the outward flow is less contracted and thus carries more kinetic energy.

Twospoons - 16-3-2018 at 14:04

If you are trying to see air currents you will want thin streams of smoke, not a room full. If it were me doing this I'd be using the commercial fog- juice, or the home-made equivalent of gylcerol+water, in a tube with a reasonably powerful heater, and a nozzle to create a stream. That would give you good control over the smoke stream.

examples

NEMO-Chemistry - 19-3-2018 at 14:04

Quote: Originally posted by Bert  
Quote:
might be a way to get better lift from less power.


Not chemistry, but-

How about DUCTED fans?
Quote:
In some cases, a shrouded rotor can be 94% more efficient than an open rotor. The improved performance is mainly because the outward flow is less contracted and thus carries more kinetic energy.


Ducted fans is exactly what I am looking at, I couldnt think of the word! Mine are made with DELL pc fan ducts, I notice the distance at the top etc seems to make a big difference.