Expt 038 -- Radial Chromatography T-Shirt Designs

Using radial chromatography, it is relatively easy to decorate T-shirts (or any other absorbent cloth material) with interesting radial patterns. This laboratory is similar to the water based experiment with filter paper.

Safety

• Because the solvent being used is highly combustible, make certain that no flame or spark sources are used anywhere near the activity area.
• Wear goggles.
• Work with good ventilation.

Procedure

The ink dot must NOT be allowed to dry on the fabric before the chromatography starts. The dots may bond to the fabric if allowed to set.

GOGGLES IN PLACE!

1. Have the instructor fill the container at your lab station with about 20 mL of rubbing alcohol.
2. Place the coffee can upright inside your T-shirt. Position the T-shirt so that the area upon which you want to place the flower pattern is covering the mouth of the can. Snap the lid ring in place over the T-shirt, and then gently pull down on the T-shirt along the sides to draw up any slack and to tighten the fabric slightly over the mouth of the can.
3. Make sure everything is ready before proceeding. Choose any one of the permanent markers and make 5 or 6 dots in a circle in the center of the lid ring. The dots should each be as small and as concentrated as possible; the circle should be roughly the size of a quarter. If a two-colored flower pattern is desired, choose a second marker and use it to make dots in between the first ones. Remember to recap the pens.

   !!!Click here to See Movie. Click |> or <| to step the slides forward or back.

4. Use the pipet to draw up some solvent (alcohol), hold it vertically over the alcohol container for a while until it completely stops dripping, then position the tip of the pipet on the T-shirt fabric in the direct center of your circle of dots. Slowly squeeze on the bulb to push some of the solvent out onto the T-shirt. It should spread out in a circle or oval as you gradually squeeze out more and more solvent. As the solvent passes the dots, it starts to spread them out radially.

   !!!Click here to See Movie. The movie is accelerated 10 times the actual experiment time.

5. Stop squeezing when the flower pattern is almost as large as you want it to be (it continues to spread a little even after you stop squeezing), and place the pipet back in the container. Do not make the patterns larger than the hole in the lid. Wait 20-30 seconds for the flower pattern to dry -- longer for bigger patterns. Dry colors are slightly brighter than the wet ones.

   !!!Click here to See Picture.

6. If you want, select a new area on the T-shirt for a flower pattern and repeat steps 2 through 5 above. Experiment by using different sized dots or by arranging the dots in different sized circles. It is best to stick with dots, and place them near the center of the lid ring. Try making flower patterns with a variety of colors and sizes.
7. When you are finished, allow the T-shirt to dry completely. Iron them to help set the patterns. Fading inevitably occurs, but to make the patterns last as long as possible, be sure to wash the T-shirts in cold water only!
8. Return any leftover isopropanol to a container in the hood.

Questions

1. Why are permanent markers used in this experiment instead of water soluble pens?
2. Why is rubbing alcohol used as the solvent in this experiment instead of water.

Handout Makeup

Name ___________________________ Class _______

Teacher __________________________

BeckerDemos 038 Radial Chromatography-T-Shirt Designs

Watch the movies.

HQ1. Describe the separations.

Answer the questions.

Curriculum-

• At the elementary level -- after discussing colors and color mixing, show color separating.
• At the secondary level -- incorporate with other separation techniques, ties in well with polar/nonpolar and intermolecular forces. Use when discussing solutions and solubility.

Activity-

• Experiment - Laboratory Only
• This activity is best if done by the students, individually or in pairs. Either provide the pre-washed T-shirts for the students, or have them bring them from home; they will want to keep their finished products.

Safety-

• Because the solvent being used is highly combustible, make certain that no flame or spark sources are used anywhere near the activity area.
• Dispense the isopropanol in 20 mL lots. If there is a spill or fire the risk is reduced with small amounts.
• Wear goggles.
• Work with good ventilation.

Time-

• Because the solvent being used is highly combustible, make certain that no flame or spark sources are used anywhere near the activity area.
• Dispense the isopropanol in 20 mL lots. If there is a spill or fire the risk is reduced with small amounts.
• Wear goggles.
• Work with good ventilation.

Materials-

(per group)(three students/group)

• 40 mL rubbing alcohol (91% isopropyl works fine)
• 1 small container (baby food jars, small plastic cups, etc.)
• An assortment of permanent pens -- Sharpie^®, El Marko^®, black, green, yellow, red, orange, blue and brown,

(per student)

• 1 plain white T-shirt, one for each student
• 1 empty coffee can, margarine tub, or any other wide mouth container that has a plastic snap-on type lid.
• 1 plastic pipet or eyedropper

Disposal-

Collect any left over isopropanol in the hood. Colorless isopropanol may be used again. Allow any colored isopropanol to evaporate in the hood.

Lab Hints-

• If the T-shirts are new, wash and dry them to remove any starch or sizing that may be present. If the students are bringing them from home, make sure they have been instructed to bring in an old T-shirt, or to wash and dry a new one.
• Cut a large hole, about 10 cm in diameter, in the center of each plastic lid; make sure that the lids can still snap in place on their respective cans or tubs. Or, instead of cans with lids, use buckets (or wash basins) and large rubber bands to hold the t-shirts in place.
• Place the small containers around the activity area, one for each group of 2 or 3 students. Place 2 or 3 pipets in each one. Use these centers to dispense the isopropanol in small amounts. Pour only about 20 mL into the container at one time. Limiting the amount at the station reduces the risk from a fire.

Observations-

• For a discussion on chromatography as a separation technique, see the explanation offered in the Background and Observation sections of BBExperiment 037 Radial Chromatography - Water. The two activities both rely on a solvent spreading out in a radial pattern and carrying the different ink pigments with it to varying degrees. There are, however, some significant differences between the two activities. Permanent pens have been substituted in place of regular pens, because their pigments are not water soluble, thus their patterns do not run or wash out as easily in the laundry. Because the permanent pens are not water soluble, though, water cannot be used to make their pigments spread, and so isopropyl alcohol is used instead.
• Also, since the chromatogram is run much more quickly on the T-shirts, the separation is not as pronounced. In addition, it appears that some of the permanent pens contain monochromatic ink -- that is, ink that contains only one pigment -- thus, there is no separation at all for some of the pens.

Answers-

Q1. Why are permanent markers used in this experiment instead of water soluble pens?

A1. If water soluble pens were used, the patterns would wash out in the laundry.

Q2. Why is rubbing alcohol used as the solvent in this experiment instead of water.

A2. Permanent markers contain inks that are insoluble in water (have little or no attraction for the water). Water would not be able to move or spread the permanent marker dyes. These same inks are soluble in isopropyl alcohol (have an attraction for alcohol).

Handout Ans.-

HQ1. Describe the separation.

HA1. Pink dye moves faster than the orange dye. The pink dye spends more time in the alcohol than the orange dye does. The blue dye moves in a large smear showing no separation.

Key Words 1-

solutions, solubility, chromatography, adsorption, separation