Ammunition Bunker, 03/10/2014 10:06:Francesco, Allora ti spiego un po' in Inglese, perche il mio Italiano non e' tanto bene. So, the cardboard, has to be treated against it's roughness and humidity, and the only way to do it is with some good old normal undercoat paint, which we normally use for furniture. The trick is to mix the paint at 90% thinner + 10% paint. This will give the paint the time to enter into the cardboard and settle. keep on applying the paint with a brush or airbrush, until you will eventually see that the paint will not enter any more. once dry, apply normal grey undercoat paint with a brush. Apply at least three coats. Leave it to dry and sand down. Believe me, you will obtain a glass mirror effect.