It marks the origin of the pen knife. Before 1850, the process for vulcanization of rubber had not been discovered, and the only way to correct a writing mistake was to scratch the ink off the ...

Color is a silent yet powerful force in daily life, capable of transforming how people feel, think, and perform. The G2 Boost Pens are designed with a variety of vibrant gel ink colors ...

There is no such thing as “black light wavelength”—so why do black T-shirts, black crayons, and black marking pens look black? Investigate a variety of black ... You can repeat this experiment with ...