Fig. 6

Prism-based screens. The left and right panels show the permissive and non-permissive sides of the screens, respectively. a-d screens based on triangular prisms. e Screen based on right triangular prisms. a and c-e screens were made of B2w screening material, b screen was made of B1w screening material. Prisms on a-c screens had 16 cm widths, while those on e had 10 cm widths. The exposed edges of a and c screen prisms had two slits with a length of 5–6 cm each separated by an uncut part of about 1 cm. a and c prisms had 10 and 5 mm wide slits, respectively. e Screen prisms had two slits with a length and width of 10 cm and 5 mm, respectively. Exposed edges of b and d had 11 pores with a 6 mm diameter and 13 pores with a 4 mm diameter, respectively. Prisms on b had two 4 mm long skirts along the exposed edge length creating an arc-shaped edge enclosing the pores at its deepest point. a and d screens had 3 prisms whereas b, c and e had only 2 prisms. The 3 prisms on a had 3 different base widths of 3, 4 and 5 cm from top to bottom