Apart from being dirty and sometimes warped, old bricks come with another handicap: they yellow over time. This is especially the case with white bricks and less so for grey and blue. It turns out this yellowing can be undone using hydro-peroxide and UV light. There are many video’s on YouTube showing how this can be done using sunlight. However, since The Netherlands is not the sunniest of places and since I did not want to be dependent on the availability of sunlight, I decided to build a UV light box to restore the color of my yellowed bricks. It uses 4 UV fluorescent tubes, 2 above and 2 below, and two Ikea transparent boxes to hold each 5 liters of 3% hydro-peroxide and the Lego bricks. Initially soaking for 3 hours with 30 minute stirs and after many batches up to 6 hours, with 1 hour stirring – the peroxide is re-used but concentration reduces over time – will do the trick.