"Changing" vs."Dark relay" comps

[AdmiralDonSnider]

Not having used any of these so far, I´m not exactly sure about the difference between changing relay and dark relay comps.

 

The former seems to serve as a visual buffer between colors, the latter to time click-on effects to the liking. Both seem to give low light, but the dark relay seems to be designed specifically for that purpose.

 

The dark relay caught my attention regarding its use in color changing shells. Lloyd told me that for a good streamer to "click-on-color" I´ll have to layer it over the cores. It is said to make the cores appear to light simultaneously despite of variations in their size, while they´d turn on "one after another" in absence of such a relay.

 

Now has anyone experience with the possible uses of the relays, especially the latter? Does it really make somewhat uneven cores appear even?Do they serve as primes as well?

 

P.S: If one could dig out the dark relay comp given by Shimizu that would be great. (including original source if possible) I can´t remember where I read it.

 

 

[Cookieman]

Here is Shimizu's formula (Pg. 187) for changing relay comp. 1 and 2

 

 

Changing Relay I

Potassium perchlorate 35%

Potassium nitrate 35%

Hemp coal(or Paulownia coal) 24%

Soluble glutinous rice starch 6%

Changing Relay II

Potassium perchlorate 8l%

Accroides resin 13%

soluble glutinous rice starch 6%

 

[KruseMissile]

In F.A.S.T there is a dark fuse comp. There is also a changing relay 1 & 2(but they create a neutral color). My source is from F.A.S.T. I have used the color changing relay #1, no video, but it makes the stars transition smooth and not so sudden. LMK which one you would like.

Brian

 

 

 

[AdmiralDonSnider]

I have FAST, but the dark relay doesn´t seem to be in there; must be another source, possibly a Pyrotechnica article.

[frosty90]

I have FAST, but the dark relay doesn´t seem to be in there; must be another source, possibly a Pyrotechnica article.

 

Both shimizu dark fuse comps have arsenic sulfide in them from memory. There is one called "Dark relay"

 

75 KNO3

8 Charcoal

7 KClO4

3 Antimony Sulfide

2 Redgum

 

 

You could probably also just use a 'BP' like formula with lots of sulfur and little charcoal, these tend to burn with a pale white light, probably barely noticeable at a distance.

[swervedriver]

From the couple of times I've tried Shimizu's change relays, here's what I gather- change relays burn fairly quickly. Not really practical for smaller stars, as the layer must be thick to be useful. You can see Shimizu's change relays burning in the sky, just not as bright as brilliant color comps, similar brightness to BP prime.

 

I like Glusatz for a dark delay/relay, but burns really slow, so not to good for timing. I used it quite a bit of glusatz recently. I imagine Shimizu's changing relays are more usefull in big shells/stars. Glusatz is an interesting effect for delayed ignition, poisonous though.

[FREAKYDUTCHMEN]

This shell http://www.pyrobin.com/files/6%20c8%20to%20blue%20to%20red%20flash.mov has a relay mix 81 perc, 13 redgum and 6 phenolic resin (between the blue and red flash), from the original formula I replaced the sgrs for resin, because it had to be rolled without water.

The layer was less than 1mm thick.

[swervedriver]

Maybe I just don't understand the usage, I couldn't notice anything different in my stars if using only 1 mm of change relay. Maybe my rolled stars just aren't uniform enough in size. I do size them, but even so they vary by at least a millimeter, maybe more as my batches are likely small by your standards Freaky.

 

That was a beautiful shell by the way. Do you see a significant difference between using the relay and not using the relay?

[Karlos]

Dark prime, darker than typical black powder? Yes, it is possible! But, which composition? Look videos!

http://www.youtube.com/user/HajdaHanabi?feature=mhum#p/a/u/0/WUvDfFurkPg

http://www2.sinfonia.or.jp/~isogai/movie/hoshi.wmv

I am stil sayig, that Japanese making colored stars with special prime and no only BP, mainly in more-petal colored peonies.

 

http://books.google.cz/books?id=X3aFQdJkmnAC&pg=PA37&lpg=PA37&dq=dark+prime+shimizu&source=bl&ots=QW_PkMOnz6&sig=v9rEQoPzvrU9rONdElBuv7STg-c&hl=cs&ei=RA4_TaqoB83zsga8k-3iBA&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCYQ6AEwAg#v=onepage&q&f=false

Edited January 25, 2011 by Karlos

[50AE]

Very good topic. I was wondering if dark relay is necessary in shells from 4" to 6", if I screen all my stars precisely so they become uniform.

Also, using perchlorate is not an option here, so I was wondering if straight sulfurless black powder could be used as dark prime. If a low reactive charcoal is used, shouldn't the powder burn slowly as the dark relay prime of Shimizu?

[pyrojig]

I dont think that the reactivity of the charcoal matters as much as the ratios.

[Mumbles]

Well, a relay composition is never actually necessary. It's personal preference, and aesthetics. I personally like it. It gives that "blinking on" effect commonly seen in very high quality ball shells. When going from a glitter or charcoal streamer to a color I don't care for it as much as when going color to color, or color to flash core. More than anything, it prevents the mixing of colors which can lead to momentary muddy flame colors.

 

I don't have my book handy, but I think in FAST he said he uses hemp charcoal, the same as in some of the bursts, so I'd not think it matters much. Typically slower burning charcoals leave more sparks than something like willow, so I'd think there may actually be an advantage to using at least a medium speed charcoal. Too fast could increase light output or course. In any case the ratios should be somewhat flexible if you need to slow down a mix, or speed it up to compliment the charcoal.

 

As far as sulfurless BP as a relay goes, it's worth a shot I suppose. Let us know how it works. You may also want to try the analogue of changing relay 1 using chlorate instead of perchlorate. You can adjust the nitrate:chlorate ratio to adjust speed I'd imagine.

[50AE]

The problem I think of, is that nitrate/chlorate and charcoal mixtures burn fast, while the perchlorate based burn slow (like BP and H3 vs KP).