I have long wanted to play with sodium, but it's the one pyrotechnic item I never managed to get my hands on as a kid. I didn't take high school chemistry, so I never saw the classic sodium-in-water demonstration. Sometime in the early 80s (when I barely knew what I was doing!) I succeeded in melting a mixture of salt, potassium chloride, and lithium chloride in a ceramic crucible using a Meker burner in my lean-to “chemlab”, and tried electrolyzing it with platinum wire electrodes, but I didn't have an inert atmosphere over it so I couldn't gather any pure metal. Later, I took college chemistry classes, but they aren't so interested in keeping the students entertained (at least in the classes I took!), so I still never saw sodium put to pyrotechnic use.
Fortunately in these enlightened days there is an answer to all of your pyrotechnic chemical needs - eBay! After looking for a while I bought two kilograms from an eBay seller for $110.
I was boggled when my two blocks of sodium showed up in a ziplock bag coated with a film of oil. Not an advisable shipping method! The first thing I needed to do was make the sodium safe. I already had some appropriate glass jars around. I also had some kerosene, but I decided it would be better to put it under mineral oil, so I bought some. Then I was left with the problem that the sodium ingots were too long for the jars, and also would not fit in the mouth of one of them. The solution was to cut it up.
Fortunately, sodium is a soft metal and can be cut with a sturdy knife with a bit of work (by just forcing it through, not sawing it). Sodium reacts with moisture in the air to form a thick coating of white sodium hydroxide that makes it look a bit like brie. When it's cut, the exposed surface is very shiny and highly reactive and sizzles when exposed to the least bit of water. I thought I'd dried the knife off after cutting it, but it was obvious that there were traces of water still on it. Nothing dangerous, though.
I first cut it into large pieces and fit as many as possible into the large jar. Then I cut the corners off of one of the large pieces to fit it in the smaller jar (a gift for my brother, who had also never managed to see a sodium demonstration). The remaining material I cut into smaller pieces and fit around the other pieces in the large jar. When I was done, I made sure there was no sodium on the knife and washed it off. I was wrong - my first demonstration of real sodium action occurred as a result of a tiny fleck of sodium on the knife, enough to fizz and make a faint pop.
Then we poured the mineral oil over the sodium. Somewhat unexpectedly, it reacted noticably - it should have occurred to me that there would be enough of a trace of water in the oil to do that. Bubbles streamed up from all of the cut surfaces. It didn't look like the reaction was accelerating, though, and the fact that the "moldy" surfaces didn't react at all reassured me, so we finished the immersion. I checked on the sodium later and it was barely reacting, so I felt safe leaving it in the garage overnight. The next morning all of the cut surfaces had plenty of sodium hydroxide on them and it was no longer reacting at all.