KNO3 Must Soak Into Charcoal...(Shimizu)

[eddiegnz1]

Page 221 in the FAST book by Shimizu says the following in regards to Charcoal based star comps:

 

"...To obtain a pretty remaining fire, it is not enough merely to mix the three components, but the Potassium nitrate must be allowed to soak into the charcoal particles. For this purpose a wet process can be effective to mix the three components..."

 

Separate from the above, I saw an article on the web that says the following (not from Shimizu):

 

"...when preparing the (Tiger Tail) stars, it is important that a wet process is used, as the act of moistening the mixture with water greatly improves the resulting fire dust...to aid in incorporating the water in to the mix many people use a solution of about 75% water and 25% isopropyl alcohol, with no less than 75% water. The alcohol helps the charcoal absorb the potassium nitrate solution by reducing water's surface tension, thereby allowing the solution to enter more of the charcoal's pores. The drying time of the composition is also reduced, as alcohol evaporates faster than water..."

 

But then I see some folks on the net saying that a wet process is not needed for charcoal stars. Perhaps the reason for the disagreement is that indeed it is not necessary to do a wet process in order to achieve a functional Charcoal based star...and it is not necessary from the perspective of safety. That said, there might be a diference in the performance of the star. There might even be a subtle diference in the look of the star...the color or density of the tail.

 

So if I do use a wet process, how do I do a "wet process" if I want to roll the stars. It seems that I wouldn't use the typical method of alternating water spray and then sprinkle dry dust, etc.

 

Have you ever seen a "wet process" charcoal based star with your own eyes? did it look any different than a dry process star?

[dagabu]

Have you ever seen a "wet process" charcoal based star with your own eyes? did it look any different than a dry process star?

 

Just a guess here but are you referring to nitrocellulose lacquer instead of water whetting? If you are, some have had great luck with the NCL binding the comp and still allowing the acetone to whet the KNO3 into the charcoal.

 

I am going to be doing some more willow stars this spring and I am going to use NCL instead of water.

[Richtee]

I guess you don't roll them eh...but press them?

[Ventsi]

So if I do use a wet process, how do I do a "wet process" if I want to roll the stars. It seems that I wouldn't use the typical method of alternating water spray and then sprinkle dry dust, etc.

 

Have you ever seen a "wet process" charcoal based star with your own eyes? did it look any different than a dry process star?

 

 

A common way to wet and roll the stars would be to granulate the star mix through a 40-60 mesh screen. Them roll with that powder, normal rolling using water as the solvent works fine but you get horrible bumps. The granulating/rolling really makes them ALOT better.

[dagabu]

A common way to wet and roll the stars would be to granulate the star mix through a 40-60 mesh screen. Them roll with that powder, normal rolling using water as the solvent works fine but you get horrible bumps. The granulating/rolling really makes them ALOT better.

 

Sorry, what? Could you explain that to me? My overworked gray matter cant process it.

[Ventsi]

Sorry, what? Could you explain that to me? My overworked gray matter cant process it.

 

 

All credits and go to Jack and Dorothy Drewes-American Firework News.

[Arthur]

IMO Dry mixed comps burn at the edge of the star, bur wet mixed comps form a fire dust tail too as they burn.

[Bonny]

A common way to wet and roll the stars would be to granulate the star mix through a 40-60 mesh screen. Them roll with that powder, normal rolling using water as the solvent works fine but you get horrible bumps. The granulating/rolling really makes them ALOT better.

 

40-60 mesh might be a bit coarse.

In his book, Round Stars And Shells, David Bleser recommends the (charcoal streamer) comps be thoroughly ballmilled, dampened,granulated, and, after drying be ballmilled 3-4 hrs to reach what he refers to as optimum rolling size...100-200mesh.

 

IMO Dry mixed comps burn at the edge of the star, bur wet mixed comps form a fire dust tail too as they burn.

 

I make TT all the time without a wet method, just a long session in the ballmill and the stars have a nice firedust tail.

[andyboy]

Rolling the stars with water is sufficient to leech the Kno3 into the charcoal. Although it is harder to roll high % charcoal stars since they don't pick up water as well it can be done.

[Lagrange]

hi, first post here,

the wet process here can be made before roling, take your charcoal and kno3, mix in water (enough to get a black liquid. Then on a stove dry out the water partialy. Stop when the charcoal/kno3 mix is more of a solid than liquid to avoid heat ignition and pour on a frying pan for drying. depending on your location you may need tu use an oven for full dryness. place the frying pan in the oven and set your oven at 90 C (194F).

this procedure will force a big part of the kno3 to recrystalize inside the charcoal.

 

when full dryness is acheive, the powder can be use in any dry/water process you want to use like rolling and the result will be in a "wet processed state".

[Miech]

I never noticed any difference at all between riced and non-riced charcoals streamers when they where rolled. Ricing might help when pumping stars, but when I roll them they get so wet the charcoal crystallizes out in the charcoal anyway.

 

It does make a difference when making stars with lampblack though. When doing that I rice the composition without binder, and roll with the toro method. This keeps dust down and prevents bumpy stars.

[JMA375HH]

I just made my first batch of tiger tail using pine charcoal. I used the wet method, heres what I did I bought a wok at the second hand store and got lucky because it was a real nice one I had to hide from the wife. anyway I measured out all ingredient's total wt 500g but added the kno3 first with enough water to get into a slurry and stared the hot plate to get the water and the mix hot. about med heat once all was warmed up I started adding the air float charcoal just enough to layer the top of the warm mix then grabbed my bottle of 75/25 water alcohol and missed the charcoal while stirring gently and keep repeating until all charcoal is mixed in, then repeat with Sulfur though Sulfur seems to blend in much easier then the air float so spraying my not be required as much.

Its also a good idea to always keep the pot stirred so you don't develop hot spots on the bottom of your pan. Keep stirring and watching the heat if the mix starts to bubble thats OK to a point, but remove from heat and let the mix cool a bit before putting the heat back to it. The idea now is to bring out most of the moisture if the slurry is still to wet. Once you see that your mix starts to stay together like a mud pie cut the heat and remove from pan onto a sheet pan sheet and spread out to harden a bit more. The kno3 will cool and start crystallizing pretty quick, so have your screen ready to go also it's a good idea to where some kind of cotton glove because the mix is still hot.

I put mine in the press then into the dryer for a full day I found out that putting to much heat on the comets will cause cracking in some along with bulging in others. So I keep the heat in the dryer moderate and this works well. I had one brake into three peaces so not wanting that I coated the rest with nc and that's work really good.

John

[Falcon2]

Hey Everyone,

 

This is my first post here so I can then get full availability.

 

Anyway I thought I'd through in my 2 cents;

 

It seems to me that a wet process is mearly to improve the burn rate and reactivity of the composition. Similar in a way BP is made and pressed, a small amount of water causes partial dissolution of the nitrate, and drying results in fine recrystallisation. A greater burn rate would give the visual impression of a better fire dust.

If it is similar to the way BP is made only 2% water would be needed, plus minus any alcohol. Any more water reduces the burn rate of material due to the creation of too large nitrate crystals.

I think that any method - even rolling uses at least this much water, so I don't see the point in granulating the composition first. I don't think that the extra time would improve the comp too much.

Just thinking about it but soaking the nitrate on to the charcoal seems detrimental to the objective; which is to light the charcoal without burning it, having nitrate in close proximity to the charcoal would cause more efficient burning and less glowing embers.

 

I love making rolled C6 stars, and I think the best way to acheive a better fire dust is to use a better or different charcoal (I make my own), which maybe improved with less cooking (of the charcoal; improves volatiles and less solid carbon). I haven't got any books on star making so I can't be sure on what other authors have said about this topic, I do have FAST though.

Mind you I don't know why you need a better dust than a C6 - thats a pretty intense amount of fire dust, especially out of mines!

[dagabu]

If pressing pucks, I would agree on the 2% but you would need more then that to dissolve anything in a charcoal comp as the charcoal would absorb all of the water you add up to a certain point. In making pulverone, the water activates the dextrine and less then 4% will result in a weak grain.

 

You can easily find a 2% weight increase in BP if the powder is left out in humid conditions and it is said that the BP will burn even faster due to the super heated steam that is created because of the additional water. You will need to fish for that one over at Passfire though.

 

With C-6 and lots of other high charcoal comps, the charcoal and KNO3 are mixed wet and the water is boiled off leaving the KNO3 in intimate contact with the inner lattice of the now empty cell structure which will increase the rate of fire throughout the star/comet. Interestingly, if one wished to do the work, this method olso works well to make high charcoal rocket motors fly with more thrust due to the intimate KNO3/charcoal relationship.

 

A treatise on this phenomenon has been written by Ned Gorski.

 

Try it some time, you may be pleased with the results.

 

-dag

[Peret]

There is a section in the chapter Shimizu wrote for Ron Lancaster's book that talks about making black powder by the "wet method". This involves dissolving the nitrate to a saturated solution in boiling water, adding the charcoal and simmering for an hour, then drying it and ball milling it with the sulfur. Shimizu reckoned this made the powder 12 times faster than simple screening and 6 times faster than dry milling. I tried this method and found it extremely messy and time consuming for only a small increase in performance. I was using commercial airfloat charcoal at the time, which gave mediocre results by any method. I haven't tried it with decent willow charcoal, which is fast enough for me dry milled. I have noticed, however, that granulating the meal with lots of water (20%) gives a much better powder than granulating with just a little, so the water definitely plays a part.

[Mumbles]

The other thing I've seen is stuff like Bill Ofca's spider shell article where he mentions that you should granulate the composition, and then re mill it partially before making stars with it for a faster burning star and thus bushier tail. I would think this would have as much to do with surface area as anything. The stars work just fine if they're just wet and made into stars. I would compare a star made from the granules to something like a sponge vs. a brick. I would think these air pockets of sorts would speed it up.

 

I wondered if using more water would do the same thing, leaving air pockets when it evaporated. I will say it doesn't explain the effect observed where the charcoal soup Shimizu talks about (my words, not his) would give an increase over just dry milling. Perhaps it allows for the nitrate particles to be even finer than capable in a mill? Anyway, to test the water evaporation air pockets I was looking at some pictures I had from last summer. Below is a picture of polverone made almost to a T of the Swisher described method. I used a 1/4 sized batch, and a 4 mesh screen instead of 3, but that's about all that is different. The method uses boiling water, and gets the comp far wetter than I would normally be comfortable with. As it cools, and it does so pretty rapidly, it significantly solidifies. With a few repeated granulations and a good breeze it's dry within a day or so. I'd imagine that this rapid drying would create the biggest air pockets to be visible.

 

I can't really make out any air pockets, but I can see plenty of nitrate crystals and that I really need to wash my hands. It should be noted that the coarse nitrate is because I didn't grind it very much, not because it recrystallized like that.

 

http://www.amateurpy...=images&img=444

[Algenco]

Mumbles, I done the granulate remill thing, it works nicely.

It creates a buhier tail with elegant firedust, worth the effort

[spitfire]

Slightly offtopic, but worth mentioning: rolling compositions known to get bumpy stars... This problem is overcome by slightly dampening the composition, granulate, dry, and mill for a very short period. In my case, 30 mins or so does the job. In most cases, especially compositions with a high Red Gum percentage, this method works.

[Potassiumchlorate]

One stupid question perhaps: what is the disadvantage of slightly bumpy stars? I made some Bleser Aqua last year, and they became quite bumpy in apperance, but the performance of the shell - 5" - was one of the best I had. Most stars ignited, symmetrical burst etc. I understand that it might not be good, if you want to make colour changing stars, but otherwise?

 

And a more relevant question: approximately how long will it take for 30 mm pumped TT stars or similar charcoal stars to dry in room temperature (18-20^oC) without any kind of drying cabinet (relative air humidity 40-60%)?

[dagabu]

One stupid question perhaps: what is the disadvantage of slightly bumpy stars? I made some Bleser Aqua last year, and they became quite bumpy in apperance, but the performance of the shell - 5" - was one of the best I had. Most stars ignited, symmetrical burst etc. I understand that it might not be good, if you want to make colour changing stars, but otherwise?

 

And a more relevant question: approximately how long will it take for 30 mm pumped TT stars or similar charcoal stars to dry in room temperature (18-20^oC) without any kind of drying cabinet (relative air humidity 40-60%)?

 

The bumpy stars are not perfectly round and will not burn out at the same time causing some stars to lag behind in burn time. Thats no problem for me but for a sharp looking shell, a perfectly round star is better.

 

-dag

[WSM]

One stupid question perhaps: what is the disadvantage of slightly bumpy stars? I made some Bleser Aqua last year, and they became quite bumpy in apperance, but the performance of the shell - 5" - was one of the best I had. Most stars ignited, symmetrical burst etc. I understand that it might not be good, if you want to make colour changing stars, but otherwise?

And a more relevant question: approximately how long will it take for 30 mm pumped TT stars or similar charcoal stars to dry in room temperature (18-20^oC) without any kind of drying cabinet (relative air humidity 40-60%)?

 

I find that drying comets on a screen that is elevated slightly on one edge with a gentle fan blowing across them from a safe distance speeds the drying process considerably. I've made 3" comets with a high charcoal content, that normally takes 3-4 weeks to dry, be dry enough handle in two days and fire in one week, using this simple method. The moving air strips more moisture from the consolidated composition than still air can. Try this method and see...

 

WSM

[Potassiumchlorate]

I find that drying comets on a screen that is elevated slightly on one edge with a gentle fan blowing across them from a safe distance speeds the drying process considerably. I've made 3" comets with a high charcoal content, that normally takes 3-4 weeks to dry, be dry enough handle in two days and fire in one week, using this simple method. The moving air strips more moisture from the consolidated composition than still air can. Try this method and see...

 

WSM

 

Thank you. I'll give it a try.

[Mumbles]

I'd give them minimally a week, but probably closer to 2-3. As WSM said, moving air helps immensely even without heat. I typically set aside a group of maybe 5 comets, and weigh them every few days. I have an idea what they should weigh in general, but when those 5 stop losing weight over a period of 2-3 weighings, I know the whole batch is probably dry. They also have a distinct sound when tapped together when they're fully dry. It gets much sharper when fully dry. It's also not a bad idea to break one or two open when you think they're dry just to be sure. I always have some defect comets that get dropped, or cracked, or chipped or something. After breaking them in half they just become rising tails for smaller shells, or go in mines.

[dagabu]

I'd give them minimally a week, but probably closer to 2-3. As WSM said, moving air helps immensely even without heat. I typically set aside a group of maybe 5 comets, and weigh them every few days. I have an idea what they should weigh in general, but when those 5 stop losing weight over a period of 2-3 weighings, I know the whole batch is probably dry. They also have a distinct sound when tapped together when they're fully dry. It gets much sharper when fully dry. It's also not a bad idea to break one or two open when you think they're dry just to be sure. I always have some defect comets that get dropped, or cracked, or chipped or something. After breaking them in half they just become rising tails for smaller shells, or go in mines.

 

Another idea is to save a comet or cossette of the same comp for reference weight and was even told that if one were to press a dry comet before the comp had water added, you would also get a dry weight to reference.

 

Lots of issues with doing this but as long as the comet is trimmed and the same comp is used, I see no real deal breaker using a known weight.

 

-dag