In this study, the effects of potassium borohydride (KBH 4 ) on maritime pine (Pinus pinaster Ait.) kraft pulp and paper properties were investigated. 0.5%, 1%, 1.5%, and 2% (based on oven-dried wood) KBH 4 added kraft cookings were carried out under the fixed cooking conditions. KBH 4 -free kraft cooking was also done as control cooking. The results revealed that pulp yield, kappa number, and beating time increased with addition of KBH 4 to cooking liquor. The screened yield increased 7.69 point (from 46,21% to 53.90%) with 2% KBH 4 addition to control cooking. The brightness values of handsheets were increased with KBH 4 addition. Strength properties of handsheets significantly decreased with addition of KBH 4 .

In this study, 5, 10, and 15 % secondary fines of recycled pulp were added to unbeaten and beaten (28 ºSR) samples of recycled pulp, Turkish Calabrian pine (Pinus brutia Ten.) kraft pulp, and European aspen (Populus tremula L.) kraft pulp. The effects of the addition of fiber fines on hand sheets properties were evaluated. The addition of fiber fines to the unbeaten pulps improved the strength properties of hand sheets. The roughness of hand sheets was also decreased with the addition of fines. When fiber fines were added to the beaten pulps, the type of pulp strongly affected the paper strength properties. The strength properties of beaten pulps of Turkish Calabrian pine and European aspen were decreased with the addition of fiber fines, while the strength properties of beaten pulps of recycled pulp were increased. On the other hand, the air permeance of unbeaten and beaten samples was decreased with the addition of fiber fines. Consequently, the addition of fines to unbeaten and beaten pulps had a more pronounced effect on European aspen kraft pulp and recycled pulp than on Turkish Calabrian pine kraft pulp. Also, the strength of paper made of unbeaten recycled pulp with the addition of 15 % fines was higher than that of fines-free beaten recycled pulp.