dyeing for a science project
Message: My daugther is in th 8th grade and she has to do a science project, she has chosen natural dyes as a project. Can you think of some ideas for a science project concerning natural dyes? I was thinking about a topic such as natural dyes vs made-made dye....pros and cons of each and possibly for a visual display tie-dying a sheet one out of natural dyes, such as blueberries, coffee etc, then made out of store boought dyes. Please suggest other projects out of dyes or just give me some ideas. Thank you for your help!
Well, the pro of natural dyeing is that it is fun....the cons are that the dye tends to wash out when laundered, the heavy metal salts used as mordants are in some cases very toxic or environmentally unsound, and the scalding hot water required for natural dyeing is unsuitable for use by children. In contrast, good synthetic fiber reactive dyes (NOT all-purpose dye!) can be used at room temperature, making them safer to use.
I don't think that comparing natural and synthetic dyes is such a great idea for a project. Admittedly, the relatively poor quality dye sold in grocery stores, which is called all-purpose dye, is not very washfast, either, and has the same drawback of requiring extended simmering of the fabric in very hot dye baths. High quality home dyeing, for cellulose fabrics such as cotton, requires the use of fiber reactive dye, which is usually best purchased by mail-order.
A key point about natural dyes is that they tend to perform poorly on cotton, but do quite well on wool, and sometimes on silk. A very nice project would be to compare a natural dye's performance on wool to its performance on cotton. You will find that most natural dyes do very well on wool, and very poorly on cotton. Why is this? It is because wool is made of protein, with the different side chains of amino acids which can react in different ways, while cotton is made of cellulose, a polymer of glucose sugar, with only hydroxyl groups sticking out. Cotton dyes poorly except with very special classes of dyes, such as the fiber reactive dyes (Procion MX and the like). The different chemistry of the two fibers is a good point to make in a science fair project.
A good project would be to either buy some white wool fabric and some cotton fabric, and compare how well they dye with the natural dyes you suggest - boil the two types of fabric separately, for an hour, with an equal weight of the dyestuff and some white vinegar - or do the same with some wool yarn and cotton yarn, which you first tie up into easy-to-use little bundles. Note that synthetic fibers other than nylon will not dye much at all; they could make a nice addition to the project, for contrast, but do not try to dye only the synthetics, as they will usually not do much. By "equal weight of dyestuff", I mean use the same weight of blueberries or coffee or whatever as you have of fabric, or even a larger quantity of dye material than fabric.
There is no point at all in tie-dyeing a sheet with blueberries or coffee unless you are going to preserve it, unwashed, as an art project. Since these "natural dyes" will just launder right out of the cotton, leaving you with an ugly dirty sheet, it's just a waste of time and material, otherwise. All-purpose dye will perform better, if you do the tie-deying by dropping the tied sheet into a large pot of boiling all-purpose dye. All-purpose dye is nearly useless when applied cold; most of it washes out in the first three launderings. All-purpose dye should NOT be used for tie-dyeing unless you are willing to simmer the material in the dyebath for half an hour at temperatures of 190 degrees Fahrenheit or above. If you wish to do tie-dyeing at room temperature you need to purchase a "tie dye kit" from a company such as Pro Chemical & Dye, Scarlet Zebra, or Tie-dyed.com (see the contact information for these and other dye suppliers on my Sources for Dye Supplies page). The tie dye kits sold by these companies contain high quality fiber reactive dye, the Procion MX type, which will work with the cool-water squirt-bottle technique.
Posted: Tuesday - October 19, 2004 at 12:26 PM