Fabulous Fiber Experiment
G.Eco's educational outreach strives to instill love of nature, scientific inquiry, and sustainability to future generations and fiber does it all! This week Dr. Golden traveled to Burlington, VT to teach middle school children about the wonders of fiber. From Arctic Musk Ox to domesticated rabbits, fiber plays an important role in trait selection, survival, and human comfort due to, for example, its heat retaining properties. We examined the structure of different animal fibers, performed a science experiment to test heat retention of different fibers, and explored different ways to process raw fiber into useful material. Best of all, we enjoyed the company of G.Eco's finest fiber ambassador, Addie the angora rabbit!
Addie is one of G.Eco's angora rabbits, and provides the raw fiber (angora wool) which can be spun into yarn for knitting and crocheting items, like hats, scarves, and sweaters, all natural and locally sourced.
Imagine each piece of fiber as a single strand of hair. It's much longer than it is wide and has certain properties, illustrated above (a). For example, the outer layer of each strand often has scales, sometimes many and rough, sometimes almost none and smooth. More scales makes the fiber feel coarse and causes it to grab onto itself. Fewer scales makes the fiber feel smooth or slippery. The cortex of each fiber strand is sometimes pigmented, providing animals coloration. The center of each strand sometimes contains a hollow core, which can add insulation and help keep animals warm. This trait could, for example, increase survival for animals that live in cold climates. Can you match the fiber cross-sections in the figure above (b - e) with the animals on the right? The answers are provided at the end of this blog.
Looking up close at different strands of fiber emphasizes variation in the outer most surface of each. Sheep's wool, far left above, has rough scale compared to polyester's smooth surface, far right above. This is why wool sweaters shrink when you accidentally wash them, because the fibers grab onto each other and don't let go!
We explored the texture and feel of different animal fibers including llama, goat, sheep, musk ox, and rabbit, and envisioned what their scale might look like and how their fiber's properties might help them survive in nature.
In the meantime, we also tested the heat retention ability of five different animal fibers by placing the fiber around test tubes, each equipped with a thermometer, and pouring boiling hot water into each test tube. We measured temperature over time to see which fiber wrapped test tube returned to room temperature the slowest, an indication of which fiber retains heat the longest.
First, however, we discussed how these cheap thermometers, bought on Amazon, do not measure temperature identically, which created a mathematical opportunity. Prior to our experiment, G.Eco. calibrated each thermometer to a standard temperature (Dr. Golden's trusted digital oven thermometer) and created calibration curves for each thermometer. The kids used calculators to plug temperature readings into regression formulas for each thermometer, which provided more accurate temperature results for our experiment.
Additionally, each type fiber was measure in advance to 1 gram to ensure we were measuring fiber quality and not quantity when determining which fiber retained the most heat.
We took measurements every 5 minutes or so, which left plenty of time to explore methods for processing fiber into more useful material.
Carding wool, like the border Leicester sheep wool above, involves using large wire brushes to align the kinky curly sheep locks into roving for spinning into yarn. Carding lines up the fibers so they can more easily be spun on a spinning wheel into yarn.
This spinning wheel (hand autographed by maker Richard Ashford) twists the carded fibers together, which increases the their strength. A simple drop spindle, however can do the same thing. Check out this online guide for some instructions.
A few of our students tried spinning on the wheel and discovered it's not as easy as it appears. Coordinating the foot peddle while also gaging the fiber's twist and tension is tricky business. One student, however, really had a knack for all.
While exploring fiber samples, carding, and spinning, we took breaks to measure the temperature in our fiber experiment. Measurements were taken approximately every 5 minutes or so. Calibrations were applied using calculators based on regression analysis for each thermometer ( i.e. "t1 vs digital" yields the regression curve T = t1*m + B, where t1 is thermometer #1, m is the regression slope of t1 vs the digital thermometer, and B is the intercept of the regression line with the Y axis of t1 plotted against digital). A great demonstration of the usefulness and power of math!
All of our fibers did a pretty good job of retaining heat in our experiment. However, the Goat Mohair, fiber number 3 (green, above) lost heat the fastest, indicating that is had lower insulative capability than the other fibers tested.
The Mystery Fiber number 5 (purple, above) lost heat more slowly than the other fibers tested, suggesting that this animal's fiber has the best heat retaining capability.
So... The Mystery Animal was...
Results of the fiber experiment showed that fiber number 3, Goat Mohair (green), lost heat fastest, reading consistently lower temperature than the other fibers at each sampling interval. The other fibers lost heat at about the same rate, but fiber number 5, Auggie the Doggie (purple), most often had the highest temperature reading at each
These results were surprising, especially after our discussion regarding thermal properties of different animal fibers and adaptation to cold.
One aspect of fiber that we discussed but could not test is the combination of undercoat fiber with overcoat fiber, such as on a musk ox, and also the change that occurs when
fibers are processed, such as how it is carded, spun, and knitted, for example. These factors can alter the heat retention capability of the fiber, as well.
Best of all, however, was getting to know Addie.
Matching Answers: (b) Rabbit, (c) Elk, (d) Polar Bear, and (e) 60-year-old woman