Cut Stars

WARNING AND DISCLAIMER:  If you are underage, then consult with your parents or guardians before attempting any of this.  You are on your own - I'm not responsible for your actions or harm you may bring to others because of your actions.  Making the items described below  can result in injury or death to you or people in your vicinity. Some things mentioned here may be illegal to make in your city, county, state, or country so check the laws that apply to you before you attempt anything described here. These notes are not complete on purpose. If you are reading them and new to pyrotechnics, then you are making a mistake. Stop now - this page is not for you. Get a beginning book on fireworks (see Skylighter or American Fireworks News (very quick shipping)  for a start) and read up. You can't make any of this work without more information so read up or join a club or ask someone to help you.

Making stars is another area of fireworks that tends to stop the beginner for a while. The purpose of this page is to show how to make cut stars in a *very* easy way.

This is about how to make cut stars – not how to make star compositions. However, if you don’t have a cut star formula, try this one:

Potassium Nitrate (powder): 50 %

Sulfur (powder): 10 %

Charcoal (powder): 20 %

Dextrin (powder): 5 %

Aluminum, magnalium, titanium, steel, or iron – 100 mesh: 15 %

 

Mix thoroughly in a large bowl and dampen as instructed below. Cut in 3/8” squares or a bit smaller for 3” shells. Prime.

 

Note:  Steel or iron will corrode – turn to rust – so they are not preferred but they can still work. You can look up how to coat them with wax if you dislike the rust part. If you don’t have a metal, substitute charcoal.

 

A couple of kilos of Golden Glitter cut stars drying in the sun

The same stars fired in mines with salute surprises. Click picture for video clip

The abbreviated technique

1. Dampen the star mix to modeling clay consistency

2.  Tamp the dampened mix into a pan of the right size. A bread loaf pan is great for 1 to 2 kilos of star mixes. An appropriate Glad food container works for smaller sizes

3. Release the mix from the pan

4. Cut slices of composition along the length of the loaf

5. Cut the slices into snakes about the width you want

6. Cut off the stars and dry them.

Three simple tricks:

1. Wet the mix correctly before cutting - it should be like Playdoh  or  modeler's clay. Let it sit for a while before making the loaf. You want the binders to take effect. If the mix is too wet, add a bit more dry to it to get it into shape.

2. Get the correct knife - a good blade can be made from a piece of sheet metal. It doesn't have to be sharp but it should be a cleaver and not used to draw across the composition. I've made an excellent blade from a cheap miter saw - I just ground down the teeth.

3. Do not slice the stars by dragging the blade through them - slice the stars by cleaving them

Much is made about making the right loaf pan; however, you can get by with a 'square' plastic container - which is actually preferred over a large loaf pan when making smaller batches.  A strontium nitrate comp is demonstrated below - since strontium nitrate is hygroscopic and takes *forever* to dry once it gets wet, parlon and lacquer thinner were used to bind the mix. However, the same technique applies to water based binding.

NOTE that if the material you are cutting is really sticky (some compositions are) then use meal or other appropriate prime to dust them - similar to the way you would use flour with sticky cookie or bread dough. This lets you cut and stack them without letting them ooze back together. I often sift off the meal flour afterwards and make junk charcoal stars for testing break timings, etc.

Drying:

Put your stars in the shade for the first day or so. If you dry them too fast they may “drive in” – meaning they dried too quickly making an impervious outer layer on each star – this stops the innards from drying and it can take weeks or even months to get them totally dry. The secret then, is to dry them slowly the first day or so and keep the drying temperature lower – say less than 90 degrees.

Priming:

Unless otherwise specified, always prime your stars. An easy way is to let the cut stars dry, put them in a large bowl, spray them lightly with water (or whatever solvent you were using) and swirl them around in a primer mix. Get about 1/16” prime on them for a start. My favorite prime is green mix – unmilled BP – with additives :

Potassium Nitrate Powder: 75

Sulfur Powder: 10

Charcoal (almost any kind) powder: 15

Dextrin powder: +5

Metal (I prefer silicon but magnalium or aluminum will do) 100 mesh: +10

If you don't have a metal then just use the green mix by itself. It will probably work.

 Dry them again.

Cut Stars as Cores For Rolled Stars

Here is a quote from John Reilly (posted to rec.pyro and reprinted with permission):

For cores for the final color or effect on round stars I find it easier and more consistent to use cut cubes as a base.  The finest Japanese shells I've seen use this technique and Shimizu describes it as well.  It eliminates the sorting and sizing of the final burn composition if the cutting is done with care.  For other single color or effect cut stars for cylindrical Italian style shells, the precision is not as critical but if you damp the star mixes properly, you can get a clean, crisp "dice" using a sharp knife or cleaver.  For example, if your core is going to be a 1/4" cube, you can make a "picture frame" of light wood whose sides are 1/4" tall. This is a bit easier and more precise than when I use a star box to press loaves of star comp.  The damped star comp is packed into the picture frame and leveled off by running a straight edge across the top of the frame. Now,  one of the three dimensions is already taken care of.  Then, the 1/4" thick "cake" is cut into 1/4" strips and then cut perpendicularly into 1/4" dice.  This gives very precise burn time
and saves the initial rollup time on a seed or shot.