I've been finding I need to reapply rosin to my bow after about 20 minuets of constant playing. I noticed this recently. I'm playing black horse hair and use pops rosin. Every day I try to do scales with the bow. Each day I take my bow out the hair is bone dry. I apply some more pops (about 4-7 strokes) and play. Today I played all my major scales and arpeggios up and down the neck. say from the F on the E string to the A on the G then up the g till I ran out of notes, back down, then to the F on the D string past thumb position etc. All 12 keys scales and arpeggios. I applied rosin 3 times as after 4 scales or so I found the bow was dry again. How can I stop this from happening? I have friends who say they put rosin on the bow on monday and then again the next monday and do the same amount of practice. The bow is silk smooth by the next morning for me. (Gear wise I'm using black horse hair that was rehired back in January, spirocore medium strings that are about 5 months old now, and a new cake of pops I bought a month and a half ago).