Thoroughly sand the surface of all parts with No. 360–400 sandpaper and carefully vacuum all the dust (The iron-on film does not stick well to a dusty surface. The dust also contains hard grains released off the sandpaper capable to ruin the smooth coating of your sealing iron quickly).
Use as light iron-on film as you can get (transparent Oracover, Oralite etc. – not supplied in the kit). Follow the instruction manual supplied with the covering film of your choice please.
