The lamp is filled with half water and half oil (or all oil if you like, but it's not as pretty!), and will burn for several hours depending on its size. The one I made will burn for a good twelve to fourteen hours, perhaps longer (I haven't exhausted it yet). All of the materials I used, I had lying around already.
There are endless variations that can be made. If you ever did the experiment in grade school with food-coloring-dyed liquids that float on each other due to different densities, you can turn this into a beautiful piece of artwork. Glycerine and rubbing alcohol work well. Cork will float between the water and oil.
Step 1: Materials
1 glass or heavy plastic bottle with metal screw-on lid
1 sharp poking implement (I used the pointy end of a metal compass, but anything sharp, like a rusty old nail*, would work just as well)
1 bottle of olive oil
1 piece of 100% cotton scrap (I used a clean old sock with a big hole in it) **It's important that it be all cotton. If there is polyester or anything else in it, it may produce unhealthy fumes when it burns.
1 pair of scissors
*Rusty old nails are dangerous and should never be used for anything.
Step 2: Prepare The Lid
Step 3: Prepare The Wick
Step 4: Combine Lid And Wick
Once the wick is through, screw the cap onto the bottle. Pull the wick through the cap so that the very bottom of it is just above where you want the water/oil line to be. If you want to fill the entire bottle with oil, you can leave it as long as you want.
Step 5: Fill 'er Up
Next, fill the rest of the bottle up with oil. If you have a large bottle, the oil will be full of bubbles - wait for them to disappear. This may take a few minutes, so find something constructive to do in the meantime.
Once all the bubbles are gone, you can put the cap back on. Drop the wick slowly into the oil so that it has a chance to sink. Be sure to screw the cap on tightly - if it's on too loosely, and by some unhappy accident the bottle were to tip over, oil could go everywhere and could start a nasty fire.
Of course, it should never tip over. But it's better to be safe, right?
Step 6: Let Sit, Then Light
The wick should last you a good long time, but if you ever need to, you can pull more through the cap or easily replace it with more cotton scrap.
The lamp may take a few seconds to light, as oil doesn't light easily, but once it is lit it should stay that way until you either blow it out or run out of oil. It is easily blown out, and the light is bright enough to read by.
Never leave a lit oil lamp unattended. As I mentioned earlier, if it were to spill - maybe a cat or dog knocks it over - the results could be very, very bad. Even with the cap screwed on tightly, fires spread very easily and more quickly than you may realize. I take no responsibility for anyone who burns their house down with one of these things!