I asked Emily's mom, Michelle to give a bit more detail about the project and below is her report. I was interested in Emily's use of metal mordants which are not recommended for dyeing as they are not safe for the dyer and the environment. But this was a science project after all and working with these mordants in a safe manner and setting offered Emily further learning through experimentation. I think Emily (and Michelle!) did a great job of testing the natural dyes, with the variables being the mordants and fabrics.
I would be happy to explain Emily's project.
She used 100% silk and 100% nylon pieces of fabric (weights of fabric varied from 11 grams to 14 grams). Distilled water only.
The mordants used were aluminum sulfate, iron, tin and as an extra experiment she used a bronze (copper and tin combination) bearing. She also did a dye bath using no mordant.
She did separate mordant and dye baths for each piece of fabric; which came out to a total of 17 individual baths. Very time consuming due to the fact that she gave herself very specific time lines to follow. She brought each mordant/dye pot to 180 degrees; once reached she then simmered for one hour and let sit for 24 hours. She pH tested each pot. Her notes were awesome.
Due to such cold weather, Emily did her dying in our basement on an electric hot plate, with the exception of the tin mordant and dye baths. I felt the tin had the potential of being too toxic, so she had to brave the cold and mordant/dye on our screened in porch. She also wore a total face respirator when doing the mordant baths. Not happy with mom when out in the cold or wearing the respirator but oh well. I did not want her to use copper or chrome. I felt that they were far too toxic to risk a chance of inhaling. Of course latex gloves were used at all times. I do have to say that the cochineal/tin combination on both the silk and nylon were my favorites. To further the experiment, Emily used a solid bronze bearing in a mordant bath to see if any bronze would leach into the water. It did. The result was a light lavender tone to both fabrics, actually similar to using no mordant except those fabrics came out light pink tones.
Emily felt her biggest challenge was using the concentrated cochineal extract on such small pieces of fabric. She ended up putting one gram of cochineal extract in 100 ml of water. This gave her percentages less than one gram to add to her dye baths. She used a baby medicine dropper to measure out the number of milliliters to use.
Emily wanted the actual cochineal insects for her display but wanted to use the extract for dyeing. I really feel that the cochineal extract is well worth the investment. The variety and vibrancy of colors were absolutely amazing. This truly turned out to be a chemistry experiment.