Giuseppe, that is fun!
The cotton pad you see is not soaked; it is the final closing over the tiny hole made for gas exchange!
The chlorine-soaked piece of cotton has long been removed from in between the two layers of plastic wrap under
Have used this method with many different seeds now, also non-orchid seeds, and contamination is pretty low, always under 10%, but germination is erratic. This can of course be due to many other reasons.