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Cases

Many types of cases are required for fireworks, but most of them follow a similar model. They are mostly cardboard tubes. Some have a thin wall and are expected to burn away (eg a waterfall case). Some are thick walled to withstand high pressure (eg a rocket case).

You can sometimes find useful tubes from commercial packing, but these are often thin and sometimes spiral rolled. Although these can be used it is often better to make your own.

The materials required are :

  • Cardboard or paper
  • Glue
  • Paintbrush
  • Former
  • A flat rolling area

Flour and water paste was used historically, but modern PVA diluted with about 10% water is clean and effective. The choice of paper is important. Too thick and it will be hard to roll, too thing and it will become soggy. I use a good quality 100g cartridge paper for most cases, but there is room for experiment here.

The former can be any non-absorbant object of the right length and diameter. Wooded dowel, brass and copper tube, steel rod and plastic pipe are all suitable.

The paper/card needs to be cut across the grain, so it will roll with the grain. If you hold a sheet in your hand and bend it both ways you can discover which way the grain goes.

You will need to do a few experiments to discover the correct length of paper for your tube. most smaller cases are rolled from one piece although larger ones can use two - this is easier than rolling a very long sheet.

Lay your cut paper on a flat surface and place the former at the end near to you. Try a dry run to ensure your former is straight and the tube does not spiral to one side or the other.

When you are sure that you are going fairly straight, paste a few inches and roll the tube tightly.

If all is well, paste the next bit and continue rolling.

When you have reached the end, roll the whole thing on the bench a few times, to ensure the final end sticks down and any surplus glue is expelled.
As soon as the end is stuck, remove the former and put the case aside to dry. Using PVA, this only takes a few hours with most cases.

For thin cases such as waterfalls you can use brown 'craft' paper to ensure a light, thin but strong case.

One tip for making long thin cases for quick-match (which are tricky to roll from plain paper) is to use a length of old fashioned brown sticky tape. This can be obtained from larger stationers. Use a metal rod as a former. Cut a length of tape and dry-roll it until round and then run down the edge with a wet paint brush. Continue to roll until the tube sticks. Lengths up to about three feet can be made by this method.

An odd case is the type used for 'volcano' type fountains. These are made using a shaped wooden former. Roll the former on some thick card and mark and cut out the shape to make a template. Then use this template to cut out lots of pieces of thin card. The segment should be long enough that it overlaps by 1/4 to 1/2 inch when wrapped around the former.

Wrap the first segment tightly and glue the edge. Then put on a another segment (glued all over) and roll it on. Continue this until the case is about 1/8 thick. They have to be quite thick as the pressure in these firworks is very high.

Put aside to dry until hard.

All case constuction is a knack which comes with practice - if a case is not quite straight it will probably be useable. If it's no good, throw it away and start again - it's very cheap!

Once you have got the knack and you have decided on the sizes you need it's worth having a good case-rolling session. That way you will have plently of dry cases ready when you need them.