Making Foolproof Fireworks Nozzles
When you're ramming clay nozzles or bulkheads into paper tubes, here are 3 things you need to know:
- Always ram your clay dry—never wet.
- Make nozzles as thick as the ID of the tube.
- Lock your nozzle into the inside wall of the tube.
First, if you're using bentonite clay, always ram or press it dry. (If you're using a mallet, the word "ram" means the same thing as hammer it.)
Do not ever wet it.
I know this is counter-intuitive. But, trust me, it works.
See... clay is really just fine particles that are flakes
When you pack dry clay powder into a tube, those flakes compact into a really hard mass that's almost like a rock. If you dampen your clay powder, it will expand. So after you ram the damp powder into the tube, it will dry and then crack. And your nozzle will fail.
Don't worry. If you are using rocket or fountain tooling, the dry clay powder will just compact around the spindle when you ram it.
If you don't have fancy rocket tools, you can still make it work.
Just use a solid wooden or aluminum rammer with a flat bottom. Pack the dry clay into a tight plug in the tube, and then drill a hole through it, as needed, for whatever the device is you're making.
Second thing to remember...
You have to make sure your clay nozzle is thick enough to hold up against the pressures of the rocket or fountain.
Rule of thumb is make the clay the same thickness as the inside diameter of your tube. For example, if you're using a 3/4-inch paper tube, make your clay nozzle 3/4-inch thick also.
Third thing to remember...
You want to seat your plug into the tube, so that it doesn't get blown out of the tube after your device ignites. Those gas pressures can really build up.
To make sure your clay nozzle stays put, ram or hammer it into your tube hard enough that you can see or feel the outside of your tube begin to just slightly bulge.
Not so much that it cracks or ruptures, just a slight bulge that you can feel in your hand as you hold the tube while you are ramming or pressing your clay nozzle into it.
This takes a little practice. And you may even break a tube or two. Don't worry. Just chalk that up to learning curve. This is literally one of those places where you need to get a feel for how it's done. But making your tube bulge just a little really seats the clay plug or nozzle into the inside wall of your paper tube.
Now, all that being said, making a clay nozzle is really simple.