Manufacturing process of
general round shell
How to making general round shell that launching at any fireworks display? Do you feel interested in it? I introduce general manufacturing process of round shell in this page simply. Off course, All pyrotechnists are not doing same work,but everyone can understand outline of manufacturing process.
Well, It may safely be said that making shell of fireworks is almost handcrafted even now. Naturally, there are some mechanize process like a making star. It's not get behind rationalization or mechanize but for greater part of process must be handmade. Pyrotechnists used to handle risky powder by the tip of a finger carefully for feel the condition of it. The spilit and carefully work by hands are still lives unchanged on pyrotechnists of today.
　　　　
Outline of making round shell
Compound chemicals
Making star and breaking powder
Setting up shell
Face papers outer of shell and drying up

Outline
　　　
Simply outline, upper figure.
Process divided into next three part, namely Compound chemicals, Making each units, Setting up into casing.
Parts that use powder or chemicals, Making star first. Others, making breaking powder. Another parts like a casings or main fuse are use ready-made goods today. But in the case of shell like competition use, some pyrotechnists who aim at high-quality finish are manufacturing each principal parts by handcraft even now.
Each parts not only one sort. For example star, It is vary size, color, change color to pack each size and kind of shell. Pyrotechnists manufacturing many kind of stars and parts.
There is a process of drying up in the sun between each manufacturing step. It is very important work for making safty shell.
Compound chemicals
　　
Compound various kinds of powder and chemicals to use. Though using more safety chemicals, this is the most carefully process even now. Pyrotechnists used to compound with always empty hands for feel the condition of chemicals.
Making star and breaking powder

"Star" is hold first important place of parts for make-up shell. Yes, all process of make-up shell is important. All process need conscientious work. But nothing is more important to fireworks than stars, for any pyrotechnists, most concentrate his efforts on making stars. For, characteristic color and changing color revealed originality and ability of each pyrotechnists. And more,in case of Japanese round shell "Warimono", one of the condition of well-made shell is keep pace of changing color of stars. All stars must be change color and going out all together. Therefore all stars packaged in shell are must be manufactured same quality and same size.
About "Coated star=Kake-boshi" that strong point of only Japanese fireworks, explain at "Color" page or "Dictionary of technical term". When growing up star as a practical matter, using "Star rolling machine=Hoshi-kake-ki. Zo-ryu-ki" today (upper photo). Put materials of stars and powder into like this revolving caldron, growing up larger little by little. If using such machine , need high revel ability of each pyro-craftsman for making them all of a size and fine glove shape.
Breaking powder in center of shell that scatter each stars to far away are made by same process like star. It made by coating black powder using star rolling machine over fruit of cotton that will be core of breaking powder.
Coat powder very thin and grow star little,then put them on drying table and dry stars in the sun (photo right). Process of making star, repeat this work elaborately and grow it little by little to finish size. Never do this work=that is little grow and dry= in short time, for homogenize extent of dry up of inside star.
→More about "Star"
Setting up shell
　　
All parts be complete, set up each parts at last. We show set up process of 6 inches peony shell as example.
1. Place finished stars inside of half package. Put in main fuse another half side package.
2. Put wrapped up breaking powder by separate paper in center of package. As this hemisphere as one unit, Make one shell by two unit.
3. Hold each half unit both hands. Such set up method call us "Pacckuri".
4. Put them togather at equator quickly.
5. After cut off hanging out paper, fix by tape temporarily each other.
6. Face paper over the shell. Paste a kraft paper over and over.
Face papers outer of shell and drying up in the sun
　　
Face paper is most important on set up process (Face paper of12 inches shell, photo right) . For bloom round shell in fine circle and larger shape, needless to say it is important power of breaking powder, more important part is "tension of casings". To put it simply, strength of casings to power of burst. When casings deter burst moderately, shell bloom more larger circle. Size of blooming circle and scattering speed of stars depend on both (tension of casings, power of burst) balance. Every pyrotechnists has its own balance. So this balance are one of their personality as style.
　 Face paper and dry in the sun give tension of casings to shell（photo left）. Paste kraft paper over and over outside casings that finished set up. Many mainly kraft paper in well-regulated turn. This process also handcraft. How many paper paste? it was decided to size of shell. and it is difer from each pyrotechnists. After face some paper and dry in the sun. Repeat this process some time and take some days. Finally round shell get to finish. But when it blooming on a large scale in the night sky, it may be the time of real finish for pyrotechnists.
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