Etch resist pens are permanent waterproof pens containing ink with etch resist properties. They are used to draw circuits on plain copper laminate that are then etched in ferric chloride.What are etch resist pens used for? Etch resist pens are used in the plating process for printed circuit board (PCB) manufacturing. They also simplify the marking of clad boards. Etch resist pens are ideal for use on plaincopper boards when an acid bath technique is being used. This process involves applying the ink directly, printing and then drawing it onto the PCB.How are etch resist pens used? Etch resist pens are filled with etch resist ink. To use them, you simply press the tip to make the ink flow and then apply slow, even pressure during use. Depending on the pen, the ink can dry instantly or take a few minutes. After etching, the ink can be removed with cleaning fluid or PCB scrub block.