Thermos engraving in 10 min

Warn­ing! Only un­der adult su­per­vi­sion

Equip­ment

• steel ther­mos;
• stick­er or sten­cil;
• cot­ton swab;
• ta­ble salt so­lu­tion;
• 9V bat­tery;
• wire with croc­o­dile clip.

Step-by-step in­struc­tions

Con­nect wires to a 9V bat­tery and at­tach a cot­ton swab to the “–” ter­mi­nal. Ap­ply a stick­er or sten­cil to a steel ther­mos and con­nect it to the “+” ter­mi­nal. Dip the “–” in a salt so­lu­tion and pass the cot­ton swab over the stick­er/sten­cil – this leaves a mark!

Sci­en­tif­ic de­scrip­tion

An elec­tro­chem­i­cal re­ac­tion oc­curs on the ther­mos, yield­ing ox­ides on the steel’s sur­face and par­tial dis­so­lu­tion of the met­al. These pro­cess­es leave a vis­i­ble mark!

A sim­i­lar ex­per­i­ment is in­clud­ed in the “Etch­ing and plat­ing” set from the MEL Sci­ence sub­scrip­tion!