Coloured or tinted glasses take away a specific part of the visual spectrum. Therefore, coloured glasses are also called spectral filter. This filtering leads to a blue, green, red, etc. tint of what you see.
If the coloured glass absorbs short and medium wavelengths, this will result in a red tinted glass because the glass only transmits long and therefore reddish wavelengths. With a spectrometer, the amount of transmission of each wavelength can be measured.
The colour of the glass is visible if there is a white illuminated background. There are many possibilities to create artificially white light, either with tungsten light, halogen light or LEDs, for example. The visible sensation through a coloured glass depends always on both, the kind of coloured glass and the spectrum of the illumination.
There are some hints from scientific research that coloured glasses can influence cognition like the speed of reading or response time, diseases like migraine and possibly cataract. Also, the regulation of eye growth and the development of myopia by coloured glasses is an open question to be answered in future experiments.
In the workshop you can find out your favourite tint among different coloured glasses, getting a new perspective of your aesthetic sensitivity.