Caroline uses a dip pen which gives both thin and thick lines. She uses a writing nib No. 5,with a ball on the end. Cartridge paper can be used, but water colour washes won’t flow so well.
First, we should think why we want to use pen and wash: which part should be mostly ink, which is strong and will be the focal point.
Method 1: Wash First
Shapes can be put in quite roughly and allowed to dry. When putting the ink features in, cross hatching can suggest shade and darker areas.
Method 2: Ink First
Lightly mark the features with the pen. Also you can draw in pencil first to get softer lines.
Trees can just be suggested by the shape of a trunk and using a wash for the rest.