| MadSci Network: Chemistry |
Hi Scott, I have done a little web digger for information on wax -- candle, car and ski. I will go on a slight tangent into candle wax and car wax, then return to ski wax.
5 to 10 pounds of fat is a good amount to start with. Rinse it off with cool water, trim all the meat scraps off (use the meat to make broth or feed it to your dog - it will be fresh and will have been refrigerated). Chop the fat up into small pieces. The smaller the pieces, the better it will render, but it is tiring after a while, so I usually cut the pieces about the size of my thumb.
Fill a large pot - I use a stock pot or a canning pot - 1/3 to 1/2 full of fat and up to about an inch from the top with water. Put it on the stove over medium heat. Rendering tallow can be a rather smelly business, so turn on the fan in your stove hood, open a window, put a fan in the kitchen, or something. Bring the fat and water up to a low boil, and keep it there for a couple of hours, stirring every 15 to 20 minutes. Skim off any foam or blood that may rise up. Be sure to add more water as it cooks down. Be patient. As the tallow and water cooks out of them, what's left of the pieces of fat will shrink up into ugly little greyish things called "cracklings."
Take the pot off the heat and remove the cracklings with a slotted spoon or a seive. If you really want to, you can render them again to get the last bit of tallow out of them. I usually just throw them out. Strain the liquid - carefully! - through a few layers of cheescloth into a large mixing bowl and let stand to cool. After a couple of hours put it in the refrigerator to chill.
Once it's chilled take it out and remove the white stuff on top: this is tallow. The water underneath will be grayish and nasty, and a layer of gelatin may cling to the bottom of the tallow. Discard the water and the gelatin, and scrape the bottom of the tallow cake clean. If the tallow is fully rendered, it will be firm, uniform in color, and smooth in texture. If, at room temperature, it is yellowish, semi-liquid, grainy, or oily looking, put it in a pot with an equal amount of water, bring to a boil, strain into a bowl, and cool again, and discard the water and impurities that settle to the bottom. You may need to do this two or three times to get all of the impurities out.
...Another excerpt...
Tallow candles should not go rancid - the process of boiling down the fat into tallow is to remove all the proteinous matter that can rot. That's why I want to do it outdoors - I'm not thrilled (and neither is my wife) with the idea of a big pot of animal fat boiling and being skimmed indoors. Several sources suggest that the candles should be stored in a cool place for several months before they are used, which is supposed to make them last longer.
Early lighthouses used oil lamps. Whale oil was the common fuel starting in the 18th C., I believe. All my sources agree the best tallow candles were made from a mix of sheep and ox fat. Lesser quality candles were made from ox (or cattle) alone, and at least two specifically say not to use pig, as it smokes and smells. Crisco is a vegetable fat, chemically treated to be solid, I think. If you try it (and I wouldn't hold my breath for success) let me know how it turns out. Several sources do talk about vegetable tallow from different plants (bayberry, a new world plant, is the most common example in this country), so I suppose the Crisco might work. There really isn't a straight wick - either twisted or plaited (braided). None of the fibres that might be used as wick material would stay together if they weren't twisted. Take a look at how thread is made - they don't call it "spun" for no reason! I don't recall beeswax having any particular smell the few times I've burned beeswax candles. I know the wax goes through several steps of purification before it is sold. Burning honey, on the other hand, has the caramelizing smell of burning sugar, as anyone who has had a boilover while making mead can tell you :-)
The resistance to water is seen as "beeding" of water drops. It is the scientific lore "oil and water do not mix." Metal and water will eventually result in deterioration of the metal especially if the water is full of impurities like road salt, dirt, and rust. Car wax keeps the water from chemically interacting with the metal and paint to prevent oxidation (rusting).
Car wax is typically made of polymers -- long chains of molecules. The polymers are carbon based. If you were to look at the surface of a car under a microscope you would see the wax polymers criss-crossing all over like a protective blanket keeping the water off the underlying paint and metal. The whole idea of Turtle Wax is to produce a protective shell on your car -- pretty clever marketing and imagery.
Car wax is similar to ski wax in some ways, but it is designed for durability not "slipperiness."
So the ski wax must have the property of adhering to the ski and repelling water/snow/ice. The property of adhering to the ski and repelling water/snow/ice is extremely temperature dependent. Also the property of the snow/ice is very temperature dependent.
Currently, many ski-wax manufacturers have different wax mixtures that are designed for specific skiing conditions (i.e. temperature, snow type, and durability).
It is relatively easy to produce a wax that can provide either good adherence to the ski and so-so snow/ice friction reduction or poor adherence and good friction reduction. The tricky business is coming up with a combination of ingredients that provide long lasting adherence, good friction reduction, and that doesn't approach the cost of a car payment per application.
I list just a few sights that go into more details of ski wax.
...excerpts from Purdue article:
Coming up with the ski wax idea was the easy part, they said. They knew from the soybean candles and soybean crayons developed in earlier contests that soybean oil could substitute for paraffin in wax. The difficulty was finding the exact formulation that would give the wax the necessary consistency, would work in cold temperatures and would reduce friction. An additional challenge was developing testing equipment and procedures they could use to prove they had developed a superior product.
They found that measuring water-repellency was a good guide to how the wax would work on the bottom of a ski or snowboard. They refrigerated flat plates of polyethylene, then coated the surfaces with experimental soybean wax formulations and two commercial ski waxes. The students then compared how fast water droplets would run off the plates.
Sincerely,
Tom "Rather Be Luging" Cull
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