Even colour, clear boards. Occasional sound pencil knots. No sap permitted
Minimal color variation. Mainly clear boards. Occasional sound knots up to 25 mm diameter. No sap permitted
Minor color variation. Knots filled up to 60 mm diameter. Occasional sound hard sap on edges permitted.
Color variation and red allowed. Filled unlimited knots. Occasional boards with worms. Occasional sound hard sap on face area.