Oil-Lamps-art - 10/21/08
"Oil Lamps & Working with Natural Oils" by Master Bedwyr Danwyn.
This article was submitted to me by the author for inclusion in this set of files, called Stefan's Florilegium.
These files are available on the Internet at: http://www.florilegium.org
Copyright to the contents of this file remains with the author or translator.
While the author will likely give permission for this work to be reprinted in SCA type publications, please check with the author first or check for any permissions granted at the end of this file.
Mark S. Harris...AKA:..Stefan li Rous
stefan at florilegium.org
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See this file for information on Oil Lamp Wick Holders.
Oil Lamps & Working with Natural Oils
by Master Bedwyr Danwyn
Natural oils are those obtained from nature by simple extraction methods, as opposed to modern fuel oils that require extensive industrial procedures to produce (kerosene from coal, gasoline from petroleum, etc.). The two most common oils used in period were olive oil and fish oil, with an occasional pressed grain oil mentioned. Whichever is proper for your persona, the manner in which these oils were burned is identical.
Natural oils will not burn at room temperature. The oil must first be preheated by exposing to a heat source, the most common method being to expose the wick to a flame for about a half minute. Once the wick has ignited, heat from the flame will radiate down into the oil coming up the wick, preheating it just in time to allow it to burn as it is drawn into the flame, continuing combustion. This means that while lamps fueled by natural oils take longer to ignite than lamps powered by fuel oils, they are also much safer because if spilled, the main reservoir of oil will be too cool to ignite. In fact, it might even extinguish the flame!
The three types of natural oils that I have tried are olive oil, cod liver oil and castor oil. Olive oil is by far the least expensive and easiest oil to obtain, and has a pleasant odor. Cod liver oil has become difficult to find, as it is primarily sold as a dietary supplement, and capsule rather than liquid form seems to be the fashion. Castor oil is still easy to find, but both it and cod liver oil are considerably more expensive than olive oil. But, if either of the latter are appropriate for your personna, the small amount required for an occasional feast still make them affordable for most. Store these oils in the refrigerator between events.
How To Burn Natural Oils and use an Oil Lamp
Using natural oils is very simple: insert a wick into the oil and light it! The method by which the wick is inserted varied by time, location, social status and so on. My research and experimentation have given me the opinion that three basic methods of wick insertion were: 1)placed, 2)supported, and 3)floated.
Placed wicks are those simply placed in the oil, with one end resting on the bottom and the other end resting on the edge of the lamp, outside of the oil. This outer end is what is lit, and burns as the oil is drawn up the wick. This is a very simple arrangement, but suffers from the drawback that since the flame can only burn on the upper side of the wick, the oil on the lower side generally drips down the outside of the lamp. It was common to place the lamp on a saucer of sorts both to protect the table from oil stains, and to recover the oil for reuse.
Supported wicks are held in place by a mechanical device so that the wick comes straight up out of the oil. This eliminates the drip problem of the placed wick, although it means more parts. The method by which this was done varied. I believe that some where held upright by a wire which was placed in a little tube in the bottom of the lamp. Other wicks may have been held upright in a tube soldered to the bottom of a metal dish, with an open slot to permit the oil to be drawn up. Or perhaps a metal support was rested on the side of the lamp or even over the top of it, to keep the wick suspended in the oil. I have even heard it speculated that little lead cones were placed in the oil to keep the wicks upright. I have found no documentation for this idea, but I have tried several versions and they all have worked.
Float wicks are wicks that are supported on the surface of the oil by a buoyant piece of material, such as a cork disk. A thin piece of metal is placed atop of the disk to keep it from igniting, and a hole pierced through the center of both permits the wick to pass through. I make my float wicks by cutting a 2Ó disk out of cork board. I then cut a metal disk out of thin (around .005") brass or tin stock, and put a 1/4" hole through the center of both. The metal disk is placed atop the cork disk, the wick is fed through both, and as soon as the exposed wick soaks up some oil, it can be lit.
The above ideas on wick insertion are largely speculative, since lamps are rarely ever found with their wicks intact. Period illustrations generally do not show how the wicks are inserted, although I do not claim to have found all such illustrations. Post period (but using the same technology) methods and current religious (and largely unchanged) methods give tantalizing ideas on how things might have been done, but it can not be claimed with certainty. For now, we have workable, period technology that is probably correct, but the research must continue.
It was common for the lamp to be only partially filled with oil, with the remainder of the liquid actually being water. The oil and water won't mix, so really there will be a layer of oil on top and a layer of water on the bottom. Even if the wick extends down into the water, it will only draw from the oil layer, and will burn exactly the same as if the lamp was filled completely with oil. I believe that there were three reasons for adding water to the lamp.
The first reason is for safety. If the lamp were knocked over, as has already been mentioned, the main reservoir of fuel will not ignite. The flame might continue to burn, however, and eventually ignite whatever it came to rest on (tablecloth, straw, etc.). Putting a volume of water in the lamp turns it into its own fire extinguisher! The second reason is also for safety. A lamp filled only with oil can become hot on the bottom as the fuel bums out. This can cause the lamp to scorch what it is resting on, and if the lamp is made of glass, it might even crack due to the heat. A lamp filled half way with water won't do this. When the oil is consumed and water is drawn up the wick, the flame will be extinguished, without the lamp overheating.
The third reason is for economy. Once you have determined your burn rate, you only need charge the lamp with as much oil as required to get you through the feast, and fill the remainder with water. When the feast is over, just throw away the water. Clean up of the lamp will be easy, since very little oil will be left, with none in the portion filled with water. Should you decide to burn the lamp longer than planned (the Comedia Troupe ran a little long...), just pour in more oil straight from the bottle. This is a major no-no with fuel oils, as the flame can jump back to the bottle and cause an explosion. But with natural oils, the oil being added is too cool to ignite, and no such flash back can occur.
For the wick, most absorbent plant fibers when properly twisted (or even scraps of cloth!) seem to work. I have tried linen, hemp, cotton and even milkweed with success. Wool was also tried, but was a poor performer as it tends to melt from the heat. Cotton worked the best, and for the price, nothing beats an old fashioned cotton mop head. Cut a strand to length, and should you want a thinner strand, just unwrap a ply or two. Insert it into your lamp, allow the oil to soak into the end exposed to air, and it's ready for use. Should you allow the lamp to burn itself out, expect to find the end of the wick charred over. This will cause it to burn poorly the next time, so before reusing the wick, simply crumble the char off with your fingers. Then, pull a little more length of wick up into the air. This is why it is good to use wicks that are longer then you actually need, as you can on occasion pull more wick up as you maintain it.
When you are done using your lamp, kill the flame by blowing on it or using an extinguisher. It will smoke a bit, but only for a half minute. The upper portion of the lamp may be quite warm, and it's best to let it cool for a few minutes before emptying it. Especially so if the lamp is made of glass, as it can crack if emptied while it is hot. Once empty, the lamp can be cleaned with a swish of dish soap and dried with a paper towel. And no wax drippings on your tablecloth!
Copyright 2008 by Theodore Lazcano. <trl3 at cornell.edu>. Permission is granted for republication in SCA-related publications, provided the author is credited. Addresses change, but a reasonable attempt should be made to ensure that the author is notified of the publication and if possible receives a copy.
If this article is reprinted in a publication, I would appreciate a notice in the publication that you found this article in the Florilegium. I would also appreciate an email to myself, so that I can track which articles are being reprinted. Thanks. -Stefan.