Summer Science Camp: Sharpie T-Shrits

This is both a Summer Science Camp idea and a previous-post update.

The pinwheel Sharpie t-shirts are a great summer science camp project.  Take the shirts, markers and rubbing alcohol outside and get creative.  Bonus: when you're outside there's less worry about alcohol fumes bothering anyone!

The update: when I was getting ready to do this project with a group of 24 students, I was trying to find some enough of the same type of container to stretch the shirts around, without making a huge investment. 

I decided to with with 4" PVC pipe (available from hardware stores), cut into 5 or 6" lengths.  You do need a hacksaw to cut the pieces, and the cutting can be a bit messy, so you'll have to determine if this option makes sense for you. 

It worked quite well for several reasons:

• The tie-dye designs don't usually go beyond 4", so it was plenty large.
• The smaller size (as compared to a shoe box or dish pan) made it easier for young hands to manipulate and stretch the rubber band around.
• The smaller size was nice for students sitting almost shoulder-to-shoulder at tables. 

The pictures included in this post are of shirts created by students in grades 3 through 5.

Chromatography: Which is Which?

 Pictured above are 2 M&Ms and 2 Reese's Pieces.  Can you tell which are which?

Do you think the brown dye used to coat them is identical?  It certainly looks like it, but you can use science to determine the difference. 

We'll be using chromatography again, separating the dyes found in each candy coating. 

To begin, cut your filter paper/coffee filter into two strips, about an inch wide.  Label one with an M (for M&Ms) and the other with an R (for Reese's Pieces).

Dip part of a brown M&M into water.  Use the wet portion to draw a line on the appropriate filter paper, about an inch from the bottom.  You'll want to go over the line several times, to make it as dark as possible.

Repeat the above steps with a brown Reese's Pieces and the other piece of filter paper. 

Set up your filter papers so the very end is in water (make sure the line is above the water level).  I used pencils to suspend my filter papers in tall drinking glasses.

Wait and watch.  After sufficient time has passed for the water to move a few inches up the paper (could be as long as half an hour depending upon the paper you use), remove the papers from the water and lay them flat to dry. 

Place the filter paper on a sheet of white paper for the best viewing and observe the differences between the two candies:

The colors are so faint, it is difficult to capture them in a photograph. 



Reese's Pieces



M&M



The Reese's Pieces is largely red with a faint blue line. 

The M&M shows a lot of orange, a little red, and a very faint line of green.

Chromatography: Spinach

Is spinach colored by purely chlorophyll (green pigment)? Or are there other pigments hiding in there, masked by the presence of chlorophyll?

Before beginning, if you aren't familiar with chromatography, you may want to review the basics, here.  

Use a quarter to rub spinach into a piece of filter paper, a couple of centimeters from the end of the paper. (If you’re doing this at home and don’t have lab grade filter paper, have no worries! A coffee filter works beautifully (that’s actually what I used with my students – why spend the money on expensive filter paper!) and even paper towels can be made to work).

 Put about a centimeter or so of rubbing alcohol in a cup.  Place the filter paper in the cup, so the end is in the alcohol, but the spinach transfer is above the liquid.  Allow it to sit.

Now, here's where it would be nice to have a picture of the finished chromatograph.  But, milk spilled on mine before I snapped a picture and I haven't had the opportunity (or spinach) to recreate it.  It's subtle, but you can find both green and yellow pigments on the paper, if you look carefully. 

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Presented at the 2003 New Jersey Science Convention.

Chromatography: Pinwheel T-Shirt

Sharpie markers may not be soluble in water, but they are soluble in rubbing alcohol.  Use this property to your benefit to create some wearable art (and science)!

Place a dish pan or plastic shoe box inside a plain white shirt.  Pull the shirt taut and rubberband it in place.

Use the markers to make a ring of dots where you want the pinwheel to appear.

Using a dropper, drop rubbing alcohol into the middle of the ring. 

The alcohol will move outward, through capillary action, and carry the ink with it.

If the ink is made of a mixture of colors, you will see the colors separate.  If it's made from a pure color, you will simply see the color radiate outward.

Move the shirt on the box and make another pinwheel. 

Get creative...
...try making your ring of dots with a variety of colors
...what happens if you make your dots in a shape other than a circle?
...what if you start with one central dot?

Chromatography: The Basics

Did you know the black ink is usually made of a mixture of several different colored inks?  You can use a process called chromatography to separate the mixture. 

Here's the basics...

Cut a piece of filter paper (or a piece of coffee filter, or a piece of paper towel) about an inch wide.

Place a dot of ink about an inch from the bottom.

Place a small amount of water (less than an inch) in a cup.  Place the filter paper into the water, so that the paper below the dot is the only part in the water.

The water will travel up the filter paper.  As it travels, it will carry some of the ink with it.  The ink that is made of larger molecules will not travel very far.  The smaller molecules will travel farther up the paper, resulting in separation. 

Now, here's how I use it in my classroom...
I usually make a sign with a silly threat on it.  Something along the lines of, "8th graders small funny."  Mature, right?  It's enough to get the students attention and I tell them that we're going to figure out who wrote it.

I then go through a story.  Something like... "Mr. Krup always has a black Sharpie.  And I saw Dr. Smith with a black Crayola marker yesterday.  Etc."  I use names of teachers in the school - people who are my friends and are good sports.

The students each get a piece of the threat that contains some ink, so they can use it for chromatography. 

Then, they take a wider strip of filter paper and make a mark with each of the 'suspect' markers.

Then they complete the same process as above with this paper, placing the end in water and letting the water wick up the paper. 

At the end, you compare the chromatography results of the evidence and your four suspect markers.  One of the four markers will match the evidence and you'll have your culprit.