The top one is the first one I made, which was bigger than my reference sizes (gathered from the many extant lamps you can even buy on eBay, see previous posts).  The bottom one is the second try.

You see them here with braided cotton wicks (trash yarn lying around in a color I don't like) and extra-virgin olive oil.  I have modern lamp oil, but I wanted to see how stinky the olive oil was.  Answer = not at all.

The cotton soaked up the oil immediately, so I lit them.

I discovered that the higher the flame was above the level of oil, the bigger it was…but if the wick stuck out above the lip of the lamp, it would burn down fast until the flame sat on the lip of the lamp again.  So, that's a variable to look at in extant lamps as well as to think about when making these things  - Lesson 1 – provide a decent gap between the level of the oil and the lip of the lamp.

Also, the wick sometimes slipped down a bit, as I carried the plate around, so the smaller lamp, which has a tighter pinch, held the wick in place better, and I didn't have to fiddle with pulling the wick up again.  Lesson 2 – tight pinch to hold the wick.  Lesson 3 – make it easy to push the wick up (I used the tip of a pointy thing…a pencil, the end of my fork…lots of things worked.

The bowl of the lamp did get a bit warm, such that a handle would be nice.  These wicks are ~8" long, and I think I might have burned about half an inch in their first use.  When they are relighted, you kind of have to push them up, which consumes more wick, but when they're burning, if the wick stays put, the wick is not consumed.  The oil is consumed.

I wonder what wick material would be used in a cotton-is-luxury-stuff culture.  I should get some hemp rope and try that.

As the oil burned down, I followed advice given in references to previous posts, and topped up the lamps with water.  Just as predicted, the lamps put themselves out when the oil had been burned away from the water, and the water had replaced some of the oil in the wick.  However, I don't see how this helps with cleanup, as the lamps are still really oily to touch when you empty the water, and the wicks are too.  Plus you can't relight the lamps until the wicks are dry again – that's a nuisance.  

I think when I use them at Pennsic, I won't bother with the water.

The lamps hold very little oil:  the large one holds almost 4 tablespoons of oil, and the small one 3 tablespoons.

Burn times:

6:52pm Wicks lit.

7:48pm Oil getting low; added water.

9:14pm Needed to stop monitoring open flame and go to bed; blew out lamps.

8:10am Wicks relit.

9:10am Small lamp guttering (and sparking!); added water, no effect on guttering.

9:20am Small lamp out.

11:03am Large lamp guttering.

11:04am Large lamp out.

Total burn time for small lamp: 3 hours, 22 min.

Total burn time for larger lamp: 5 hours, 15 min.

The small lamp and large lamp have some differences in their geometric construction besides their size, being pinch pots.  If I cared to figure out why (I really don't) I would suspect flame size (measured with light meter? and/or height from oil level to lip) and also wonder about the steepness of the sides of the bowls – the smaller lamp's walls are much more vertical, and the unproportional difference in flame size is suspicious.  I should probably time them on another occasion.

The lamps are fun, and I think I'd like to make more.  Kerstyn says the green glaze I chose is the oldest, simplest color glaze she knows about.  I think my next try will have multiple wick holders, and a molded handle somehow.  These lamps have holes in them so that I can string them up, on wire for safety…though I wonder if string would work.