Scientific decorations for kids

Un­cov­er a felt-tip pen’s com­po­si­tion in just a few min­utes.

Safe­ty pre­cau­tions

Warn­ing! Only un­der adult su­per­vi­sion.

Equip­ment

• cup of wa­ter;
• den­tal cot­ton roll;
• dark green/dark red/black felt-tip pens;
• fil­ter pa­per;
• scis­sors;
• pen­cil;
• thread.

Step-by-step in­struc­tions

Draw a small cir­cle in the cen­ter of a disk of fil­ter pa­per with a green felt pen. Soak a den­tal cot­ton roll in a cup of wa­ter and place it in the mid­dle of the green cir­cle – over the course of a few min­utes, an el­e­gant pat­tern of sev­er­al col­ors emerges. Op­tion­al­ly, you can trim this fil­ter pa­per into the shape of a light bulb con­tain­ing the re­sult­ing pat­tern and draw a base on it with a pen­cil. You can string a set of such “bulbs” and make your own cre­ative hol­i­day lights! If you al­ter­nate with us­ing dark red or black felt pens, your string of fes­tive lights will be mul­ti­col­ored!

Process de­scrip­tion

As it turns out, a dark green felt pen (just like dark red or black) is com­posed of sev­er­al col­ored com­pounds that com­bine to pro­duce dark green. The mol­e­cules of these sub­stances have dif­fer­ent chem­i­cal na­tures and, as a re­sult, in­ter­act with pa­per in dif­fer­ent ways: some of them move through pa­per more quick­ly, and some more slow­ly. We can ob­serve this us­ing the cap­il­lary ef­fect: the wa­ter we add moves even­ly through the fil­ter pa­per, car­ry­ing the dyes with it. This sep­a­ra­tion tech­nique is called pa­per chro­matog­ra­phy. How­ev­er, the com­po­si­tion of these felt-tip pens can vary de­pend­ing on the man­u­fac­tur­er – if the ex­per­i­ment doesn’t work with one par­tic­u­lar dark green mark­er, try an­oth­er one!

A sim­i­lar ex­per­i­ment is in­clud­ed in the MEL Chem­istry sub­scrip­tion!