33 replies to this topic

[bernie]

The following describes how a traditional roman candle is put together. It's a rather basic device but is a challenge to get all the elements tuned to perform just right. If you are compelled to construct a roman candle it is suggested that you start with a single shot version. Then a two shot and so on.

A good quality candle ejects a star up to it's apogee then just turns over and goes out. Like a candy cane. Unlike many candles that are seen in todays market a traditional candle uses a delay made of....you guessed it, a modified black powder composition. This adds extra beauty to the device by producing a fountain effect. In some cases a variation is used when colored chlorate stars are used to avoid the incompatability issues between chlorate and the sulfur in the delay comp. We will keep things simple by just using charcoal stars.

THE TUBE: More important then you might think. 3/8" - 1/2" inside diameter, 5" - 10" long and a wall thickness (approx. 1/8 - 3/16") stout enough to withstand a small lift charge. Though hand rolling tubes is considered to be troublesome by many it will ultimately result in a useful skill being acquired as well as an outstanding candle tube. Does anyone have a good link for tube rolling?

THE DELAY COMPOSITION: Lancasters A & B ( thankyou )

KNO3 - 50 - 55

Meal gunpowder - 22 - 15

Charcoal 40/100 mesh - 11 - 8

Charcoal 30/60 - 11 - 8

Sulfur - 6 - 14

I don't think it's too much of a leap to modify the above to suit your needs. The meal can be substituted with it's basic ingredients as long as it is all mixed together very well. Once again a ball mill proves very handy. The meal makes it burn faster and cleaner. The charcoal gives effects. If you use a modified version of the above it is recommended that the composition be made into a soft grain first by moistening it with water and scrubbing it through a window screen then allowing it to dry. No binder is used. The delay serves as the 'fuse' between stars/lift.

STARS: a variety of stars and inserts are used in candles. To keep things basic we will be using chrysanthemum # 8.(Suggestions are welcomed below.)

KNO3 - 49

Sulfur - 6

Charcoal pine (or other) 40

Dextrin - 5

The ingredients are well mixed and made into pumped stars of the appropiate size so they can slide down your candle tube freely but without too much slop. Round stars will also work.

Rammers: aluminum, brass or wooden dowells a few inches longer than your tube and of a diameter that will slip in and out readily.

Ramming base: this is optional but handy. It will help steady the long candle tube and can be as simple as a block of wood with a hole bored the same size as the outside diameter of your tube.

The procedure: insert the candle tube into the ramming base. Charge two teaspoons of clay into the tube and consolidate well with a rammer. Shake excess clay from tube. Drop a charge of FFg or similar on top of clay. By volume measurement this should be approx. a 'pinch'. Now slip a star down the tube. A few teaspoons of candle composition is gently rammed above the star. It is now simply a matter of repeating the lift,star,candle comp. exercise until a few inches of tube remains. Additional delay/comp is rammed on top of the last star and gives the effect of a weak fountain.

General observations: it should be noted that the last star to be ejected has a longer bore to be shot out of then the first star that is shot. For this reason a tad bit more lift is charged under the first star that is fired. This is determined by trial and error. In a 'perfect' candle all the stars ascend to roughly the same height.






This is an ongoing affair and more information will be added over time.

For additional instruction with pictures click Matts website in the members list area. Thanks Matt.




[Edited on 3-8-2003 by bernie briden]

[Edited on 4-8-2003 by bernie briden]

[Rhodri]

I love these. They are so simple to make yet really effective.

I'd really like to know how to make a candle like this:

It's lit, it produces a great fountain effect then a star, then more effect, another star and so on. Maybe finish with a bang or something like that.

How are these fused? I put a fuse at the bottom - but then that's only one shot.

A repeater is something I haven't tried.

[leniol]

I'm guessing that you could put a small salute in the bottom to be ejected rather than the final star; that would give the bang. As for the candle effect, what about ramming candle comp on top of the delay/star/lift sandwich? That's my pennies worth but I'd like to hear from someone who really knows

[zanes]

I assume the delay is 'stuck' to the bottom of the star, or is it just rammed above the bp? there was me faffing around, wondering why my stars wouldn't light.
*slaps head*

Doh!

would rolling the stars in bp work as well?

[bernie]

lift then star then delay. repeat. Will get back to the above when the mood strikes me.

[mrpyromx]

ok i know this is a old topic but im new here and was just going threw checking out the forum. ok on to the candle, i use a small amout of fine saw dust mixed with 3f BP and dark aluminum, mix it 30BP 30ALU and 40 sawdust all by weight. for the delay.

[Rhodri]

Sounds, or rather, looks interesting!

[mrpyromx]

it give a little kida glittery sparkey effect out of the tube between the real effects and a little delay.

[karlfoxman]

Just made a 1.5" Roman candle - Lavendar & Yellow crossettes. 8 shots.

Comets:

1.25" Crossettes made with wolter tooling, the yellow is based on a veline formula, I sub the Strontium carbonate with Cryolite to give a lovely yellow. The lavendar is veline blue with 2 parts strontium carbonate added. It gives a nice very pale purple colour.

Delays:

The dalays are made from a 1.5" card disk and felt wadding cut to 42mm, the disk is glued to the bottom of the felt wadding. Then a hole is drilled to accept a piece of chinese fuse that will burn for 3 seconds. The top part of the fuse is crossmatched to ensure it takes fire. The bottom part of the fuse is coated in bp slurry to transfer fire to the next comet. The time fuse is sealed on the bottom with hot glue.

Lift:

This measured so the shot 8 is 6.5g shot 7 is 7g shot 6 is 7.5g shot 5 is 8g shot 4 8.5g shot 3 9g shot 2 is 9.5g and shot 1 is 10g. This is done because as the length of the tube gets higher you need less lift to get a decent hight.

All the crossettes are placed prime up, this makes sure they take fire before the lift charge does. The prime should transfer fire to the lift below, the lift then lights the crossmatch and then the next timefuse and the process starts again.

Here is a picture of the candle complete, a piece of quickmatch goes directly to the first crossettes prime and the lift. The tube used is 1200mm long IIRC. Its full 3/4 way up.

[EnigmaticBiker]

Just made a 1.5" Roman candle - Lavendar & Yellow crossettes. 8 shots.

Here is a picture of the candle complete, a piece of quickmatch goes directly to the first crossettes prime and the lift. The tube used is 1200mm long IIRC. Its full 3/4 way up.

Reckon that will look great when you fire it, I'm just starting to make roman candles so will stick with Bernies' method until I'm proficient.

Roughly how long did it take to make? It does seem really elaborate.

[Creepin_pyro]

Very tasty looking candle you've got there Karl - please get some photos/video of it in action!

What kind of construction method and break are you using on the crossettes? Being 1.25" I'm assuming they're a little more forgiving than smaller ones, but I've never had much success breaking colour crossettes...

Also interested if you have any photos of the delay units. I've seen a few large candles dissected and it looked like a rather fiddly process, especially without any kind of automation.... I'm sure it wil perform wonderfully though!

[karlfoxman]

Cheers for your comments, the xettes are pumped with my hydralic 12 ton press and then when dry I wrap in 2 turns gummed 50mm tape. Then stick a piece of blackmatch in the cavity, these im trying with 1g 70/30 flash. I should have really tested one at a time but im wanting to test my delays/wads too so I made a full blown version. Not sure if it will all work but we shall see, ill post the vid whatever happens! When I made larger xettes they did break quite well but the burn was a little too long and the were on the way down

I will take pics of the wads as I build the next one! They aint that hard to make but I really need to make a punch as cutting 10mm with a knife aint fun!

Edited by karlfoxman, 14 October 2006 - 01:39 PM.

[karlfoxman]

Well it sort of worked, no crosettes split so that needs work. For some reason the some comets broke up on lift. I think they were not pressed hard enough. Most of the wads and timings worked so I know thy only need lookin at and making a bit bigger. Back to the drawing board buit im going to make them work!

Karl

Here is the video! Dont laugh at poor work
Video

Edited by karlfoxman, 15 October 2006 - 07:39 PM.

[5thElement]

Looked decent to me

[weknowpyro]

My roman candles ussally use stars of about 1/2". Spider stars are my favorite for the candles. The delay mix i use is very effective and i use about 5g of it between each star and this gives about a 3-4 second delay.
The compostion is from the RSOC book 'The chemistry of fireworks'.
Roman Candle delay mix-

KN03- 52g

Soft grain blackpowder- 22g

Charcoal 40 mesh- 21g

Red Gum-5g

I then ball mill this together for about 4 hours.

Edited by weknowpyro, 04 November 2006 - 03:11 PM.