Japanese Shells

[Edwin]

7 hours ago, Zumber said:

For pillar ( pumped star/ comet) Changing relay is not necessary rather sequence of stars composition should be capable of igniting next layer of colour composition.

In encyclopedic dictionary I have seen kraft paper tube is used where three or more colour composition of desired thickness is pressed and at the end prime layer is applied, this technique is useful in mines but for round stars changing relay is necessary.

Isn't it because round color changing stars have a tendency to have the colors bleed into each other had there been no relay? Could it be that the kraft tube star burns only on one side of the cylinder and is therefore a bit easier to control the flame compared to the round star that burns radially?

[Zumber]

Dont you think step mixing of two colour star composition produce unwanted light and flame? Then how clear visible colour change is possible?

 

[Edwin]

I was just theorizing. Relating what I observe in practice with theory is what really stumps me. 

[Mumbles]

Some color changing stars do in fact use a relay type composition.  As you said, rolling one color comp directly onto another can cause the color to get kind of "muddy" for a bit.  In the above blue to yellow example, the interface would probably look a bit greenish.  Dark relays tend to make the transition look crisper in my opinion.  They typically burn kind of a dull red when seen close up.  In the sky it's generally imperceptible.  Even if you can't detect it in the video, it doesn't mean it's not there.  

Ghost shells really aren't all that complicated in theory.  It's the technique and putting it to practice that takes high levels of skill.  Building a number at once can help just due to the economy of scale.  It's easier to accurately roll a few thousand of the same star for one "segment" of the ghost shell, than it is to roll like 40 for a single shell.  

[Zumber]

6 hours ago, Mumbles said:

Some color changing stars do in fact use a relay type composition.  As you said, rolling one color comp directly onto another can cause the color to get kind of "muddy" for a bit.  In the above blue to yellow example, the interface would probably look a bit greenish.  Dark relays tend to make the transition look crisper in my opinion.  They typically burn kind of a dull red when seen close up.  In the sky it's generally imperceptible.  Even if you can't detect it in the video, it doesn't mean it's not there.  

Ghost shells really aren't all that complicated in theory.  It's the technique and putting it to practice that takes high levels of skill.  Building a number at once can help just due to the economy of scale.  It's easier to accurately roll a few thousand of the same star for one "segment" of the ghost shell, than it is to roll like 40 for a single shell.  

Can you recommend good dark delay compsition please.?

[Sulphurstan]

16 hours ago, Zumber said:

Can you recommend good dark delay compsition please.?

@redbullzuiper has an excellent dark relay composition. He may disclose the recipe 🤔?

[Crazy Swede]

A very good dark relay composition can be made from potassium nitrate and Novolac (phenolic resin powder containing hexamine).

Start with 90 % potassium nitrate and 10 % Novolac. To this you add  binder (dextrine or rice starch) to desired binding strength for your star rolling application. About 4-5 additional percent is often enough.

If the composition has troubles igniting next layer, you can try replacing up to half of the amount of potassium nitrate with potassium perchlorate to increase the temperature.

[Zumber]

7 hours ago, Sulphurstan said:

@redbullzuiper has an excellent dark relay composition. He may disclose the recipe 🤔?

Can you post if you have?

[Zumber]

7 hours ago, Crazy Swede said:

A very good dark relay composition can be made from potassium nitrate and Novolac (phenolic resin powder containing hexamine).

Start with 90 % potassium nitrate and 10 % Novolac. To this you add  binder (dextrine or rice starch) to desired binding strength for your star rolling application. About 4-5 additional percent is often enough.

If the composition has troubles igniting next layer, you can try replacing up to half of the amount of potassium nitrate with potassium perchlorate to increase the temperature.

I dont have novolac but I do have phenlolic resin and hexamine seperately.

[ThunderEx]

Isn't Novolac just phenolic resin?  Tried to find out more...old posts seems to treat them both as the same. Maybe there was some confusion in the beginning when phenolic came about.
To my understanding Hexamine will act as a cross-linking agent and make the phenolic resin "cure" very hard, but does it also provide other properties in this application?

[Zumber]

Yes ....Here in our reagion two varieties are available one is white form and other is yellowish white or light brown.

Yellowish phenolic have smell.

Edited March 20 by Zumber

[Crazy Swede]

In this application, I would guess the added hexamine contributes to lower flame temperature and therefore less luminous flame.

Phenolic resin powder of this type, it usually has a light yellow colour, contains about 10 % hexamine for cross-linking and has a bunch of industrial applications outside the world of pyrotechnics and is therefore rather cheap. It does not cake to the same extent as freshly milled phenolic resin of other types usually do so it is very popular as a reactive organic fuel in pyrotechnics and works well as a red gum replacement.

[ThunderEx]

Cool! Tack!  I have only seen the yellow type, and that probably explains why they are mixed up/used as the same then. 
 

[Zumber]

3 hours ago, Crazy Swede said:

In this application, I would guess the added hexamine contributes to lower flame temperature and therefore less luminous flame.

Phenolic resin powder of this type, it usually has a light yellow colour, contains about 10 % hexamine for cross-linking and has a bunch of industrial applications outside the world of pyrotechnics and is therefore rather cheap. It does not cake to the same extent as freshly milled phenolic resin of other types usually do so it is very popular as a reactive organic fuel in pyrotechnics and works well as a red gum replacement.

The phenolic yellowish version I have has a strong smell like you are breathing in paint shop.

And it cakes rock hard...before use I use hammer to crack it into pieces then I grind.

This version improves colour star deepness to great amount than white phenolic resin which is also available here.

The white version is odourless.

I am not sure yellowish version contains hexamine or not.

-Zumber

[Edwin]

On 3/18/2024 at 6:22 PM, Mumbles said:

 In the sky it's generally imperceptible.  Even if you can't detect it in the video, it doesn't mean it's not there.  

Ahh okay, I see. So that's the case for stars transitioning from one color to another color that's of similar brightness and intensity to the first one. Now I'm wondering what it would look like if it was a very bright/hot comp transitioning into a dimmer color with relay, i.e., brilliant Mg/Al red to a dim blue. 

[Mumbles]

There are two main varieties of phenolic resin.  Novolac and Resol resins.  Novolac generally has an excess of phenol relative to formaldehyde, and is made using an acidic catalyst.  Resol generally has an excess of formaldehyde relative to phenol and generally utilizes a basic catalyst.  One of the more notable difference between them is that Novolac resins regularly use hexamine as a cross-linker, where as resol resins typically contain enough functional groups remaining to be considered self-curing or self-crosslinking.  There's other differences, but you'd go down a huge rabbit hole trying to fully understand the broad field of these resins.  Due to some property differences,  novolac resins are much more common for pyrotechnics.

We siphon material off of other more established industries.  It's not uncommon to find novolac pre-mixed with hexamine for direct sale and use by the end consumer.  Resin with or without the curing agent added can both be sourced if the desire is there.  

[Zumber]

7 hours ago, Mumbles said:

There are two main varieties of phenolic resin.  Novolac and Resol resins.  Novolac generally has an excess of phenol relative to formaldehyde, and is made using an acidic catalyst.  Resol generally has an excess of formaldehyde relative to phenol and generally utilizes a basic catalyst.  One of the more notable difference between them is that Novolac resins regularly use hexamine as a cross-linker, where as resol resins typically contain enough functional groups remaining to be considered self-curing or self-crosslinking.  There's other differences, but you'd go down a huge rabbit hole trying to fully understand the broad field of these resins.  Due to some property differences,  novolac resins are much more common for pyrotechnics.

We siphon material off of other more established industries.  It's not uncommon to find novolac pre-mixed with hexamine for direct sale and use by the end consumer.  Resin with or without the curing agent added can both be sourced if the desire is there.  

Thank you for more clarification.