What you see above is a home-made PCB. No, this isn’t an example of a terrible toner transfer job, but rather evidence of the ravages of time. This board is seven years old, and the corrosion and broken traces show it. Luckily, George already has seven years of environmental data for a cheap DIY soldermask.
Seven years ago, George took a piece of copper clad board, masked half of it off, and sprayed it with fast drying polyurethane. After drying, he put it on a shelf in his garage. The results were fairly surprising – the uncovered portion is covered in verdigris, while the coated half is still shiny and new.
George took this a bit further and experimented with other spray can coverings. He found Testors spray enable worked just like the polyurethane, burning off when the heat of a soldering iron was applied, and also passed for a professional PCB.