11 replies to this topic

[NeilB]

How do I get 80 mesh charcoal?

Do I push through 80 mesh and keep what doesn't fall through 100 mesh
or
push through 60 mesh and keep what doesn't fall through 80 mesh

Thanks everyone.

[RegimentalPyro]

The first method will give you particles smaller than 80 but larger than 100,

 

The second will give you particles smaller than 60 but larger than 80

 

Both are probably about right for a formula that calls for 80 mesh charcoal - (I'd use the first - Generally formulas give the maximum mesh size), but if you are especially pernickety then find charcoal that passes a 79 mesh screen but is retained on an 81 mesh screen.

 

Hopefully this post helps......

 

 

(What was the formula by the way?)

Edited by RegimentalPyro, 20 October 2017 - 10:53 PM.

[NeilB]

Thankyou, will use the first method.

The formula was,
Slow gold by David Buell
36% potassium nitrate
29% charcoal air float
14% charcoal 80#
9% sulphur
7% titanium sponge 40-80#
Dextrin 5%

Neil.

[RegimentalPyro]

Ah - As I understand it.....

 

In this formula the charcoal gives the orange gold colour through incandescence (The Ti will give the impression of yellowing the orange as it imparts white flashes throughout the effect)

 

The C particle size dictates how long the orange sparks last, and their density in the sky. A large particle will be long lasting but there wont be many of them. A small particle size will yield a shorter burning "firedust" effect which can be more subtle and pleasing, but not very long lived.

[NeilB]

Cheers regi, really do appreciate informative answers like this.

[cooperman435]

My understanding has always followed that 80# would be particles that passed an 80# and included everything down to air float. 80-100# would be particles that passed 80# but were retained by 100#. The clear issue with just the 80# specification here being that if particle size distribution is different with each batch made the effects can in some cases be quite significantly altered however the 80-100# is a far tighter control on the range and percentage of sizes in the batch.

Slow gold isn’t one of them though from experience and copes well with varying batches

One thing to bear in mind from neilb’s origional post is that “pushing” charcoal through a screen (I’ve read that to suggest using the screen as a grating device rather than a sieve) won’t give a partical size of that grade. You must crush/grind/grate/mill etc your charcoal then sieve it to seperate the grades out. Grating it with an 80# screen will result in considerably finer particals that I’d guess would all pass 100# or even 150% with ease.

[NeilB]

Hi phill, you read right, that is what I was going to do lol. So do I grind/mill the charcoal, then "sieve", keep what is retained on the 100#, regrind what is on the 80#?

Neil.

[cooperman435]

Bang on, however I’d simply keep everything that passes 80# together and use that as it’s what I did. (Forget the 100# sieve completely)

Remember in the composition that the fine air float is the fuel to burn in the star, the larger particles are ejected as the gold streaming sparks. Without the air float which you’d have lost by not using the parts that pass 100# you have no fuel to burn in the star it’s self.

[Arthur Brown]

Remember every time that the method may be more important than the recipe. With Slow Gold the instructions I had were to mill parts together then add the remainder and screen mix all together. It's the mixing method that determines how the star head and tail will function. Sometimes you just can't get something to work and it may be simply that the mesh size distribution within a sieve range simply isn't the same as before.

[cooperman435]

Yep I did mention that already above by saying slow gold coped well with varying batches

Trying to get close to similar processes is ok with some compositions but exact partical distribution is needed with others .

[NeilB]

Yes, I will be milling the most part, then screen mixing the 80# and titanium then rolling them.

Neil.

[Tinderbox]

I use a slow gold recipe from Shimizu. However, I like it to hang forever so I use bbq lumpood. Whack it in a bullet blender, seive it through just an actual kitchen seive. Probs roughly 40#. I use everything that falls through. I then weigh what I need from that and then I pop it back in the blender along with the sulphur only. Not the KNO3!! I like to get the S and C intimately blended. Then I screen this in with the nitrate and dextrin. Daiper in the Ti, wet and press.
Makes a stunning show and lasts ages. Gotta get that stuff high up though as it rains fire everywhere if not.

I find playing with the sulphur content has a nice variable. I think if you get it just right you are actually creating millions of senko hanabi type gold sparks with the Titanium igniting in a delayed twinkling fashion.

A very gorgiving formula with loads of room to play.

Look into an effect the Japanese call Majestic Arc Transformation also known in the USA as the Firefly effect. Uses similar ingredients and when done well looks just awesome. Gold firedust tendrils followed by a delayed sweeping change to white.

A good newbie one.

Edited by Tinderbox, 23 October 2017 - 10:59 PM.