“This project will help you to expose correctly your cyanotypes under the sun light. Because its UV component is variable in time, and depends of many factors, this tool monitor the accumulated UV dose by measuring every second the actual intensity. Once you calibrate this tool, you will can reproduce the results independently if is a sunny, cloudy or rainy day. The principle upon this works is what in mathematics is know as Numerical Integrator . In a simple case, let’s assume a certain UV value which is constant (I), and takes some time (t) to properly expose our cyanotype. Now, if we double the UV intensity (I * 2), the time to have the same correct expose will be the half than before (t / 2).”