Chemistry Tie Dye Project
How does tie dying fit into the chemistry classroom?  Well, it probably is a strech...  And it certainly isn't mentioned in the California chemistry standards.  But it does involve chemical pigments, the cellulose molecule, light waves, etc.

I have been doing tie dying as an end-of-year project in my chemistry classes for about 7 years now. The activity has become well known at our high school, and students look forward to it all year. Several other chemistry and science teachers have jumped on board with the activity also, so over 400 students are participating each spring.  On this page I have outlined the process and methods which I use, which has enjoyed a steady improvement in both tecnique and results over the years.

Materials
When I first started this lab several years ago I used the cheap Rit(TM)-type grocery store dyes.  These produced fairly poor results.  I searched for better dyes on the Internet, and now exclusively use fiber reactive dyes from the Dharma Trading Company (http://dharmatrading.com).  These dyes not only come in a very wide selection of colors and sizes, but also provide EXCELLENT results. I have not tried dyes from other sources, simply because I have been so happy with these.

Although dyes are available for different fabrics, I always order the dye for natural fabrics (cotton, cotton blends, linen, hemp, etc).  Since most tee shirts are 100% cotton, these work well.

On the Dharma website, click on the "dyes" tab, and then on "dyes for tie dying" to get to the "Dharma Fiber Reactive Procion Dyes". I routinely order the 8oz size containers.  I use approximately 20 different colors, with these being the most popular:

lemon yellow
turquiose
hot pink
scarlet
bright green
jade green
jet black
fire red
midnight blue
palomino gold
safari grey

fire engine red
brilliant orange
golden yellow
caribbean blue
ice blue
deep purple
electric blue
plum blossom
peach
avocado green
Other materials that will be required, with the sources that I use:

-16 or 32 oz spouted bottles - one for each color (from Dharma)
-2 to 5 gallon buckets for pre-soaking (I use empty 5-gal cat litter buckets, or cheap ones from Wal Mart).    You will need at least one for every period or class of 30 students.
-Soda ash (sodium carbonate), about 5 or 10 lbs (from Dharma)
-Aluminum roasting pans, about 30 (one for each student in class).  These are used to hold under the shirts as they are being tie dyed.  I buy them in bulk at Costco or Wal Mart.
-Latex or vinyl gloves - at least one pair for each student. I purchase these in bulk on EBay.  I can usually purchase 1000 vinyl gloves for about $32.00 (inclucing shipping).
-Rubber bands for "tying".  Buy in 1 lb bulk at Office Max, Wal Mart, Costco, Staples, etc.
-very cheap 1 or 2 gallon plastic bags, at least one per student.  Used to store dyed shirt overnight before rinsing they dye out.  They will also need one to take the wet shirt home.  (Wal Mart, Costco, etc)
-Permanent markers (to put their name on their shirt)
-Lots of paper towels!

The Process
I start reminding students to bring in their shirts several days before the activity begins.  I show them a slide show of the shirts from previous years to get them excited about the activity, and allow them to only bring in outer clothing items (shirts, shorts, pants, socks, etc) and not underwear.

The fiber reactive dye requires pre-soaking in a soda ash solution.  The Dharma website suggests at least a 20 minute soak, although I usually have them do it overnight.  This allows me time to mix the dyes and otherwise prepare.  I put about 1 cup of the soda ash in a 2-5 gallon bucket of cold water.  Make sure the students have written their name on their chlothing item with an indelible marker.

The following day students do the tying and dying.  The shirt is wrung out (not rinsed!).  They then lay it out on a table and fold it in the desired shape for the desired pattern.  There are lots of tutorials online that show the different tieing methods, including the projects page at Dharma Trading.
I use rubber bands to hold the shirt together for the dying process.

I have the dyes pre-mixed before the start of class. The dyes lack clear information on mixing. However, I seem to get the best results by using about 5 scoops (see above right) per 16 oz bottle.  The addition of about 1 tsp of urea (from Dharma) is supposed to help with dye uptake, although I have not noticed observable differences when using it as compared to using the dye only.

The different dye bottles are then set around the room, along with labeled swatches that show the finished color. The students simply make their way around the room to apply the dye.  When finished, the shirt is placed into a plastic bag and left to soak overnight.  Then next day the shirts are rinsed out in the sink until the majority of the extra dye is removed.
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