Hi, im using gelish and shellac since almost 2 years now. I had the exact same problems with gelish top coat brush... I clouldnt finish my clients second hand, and had to used another brush. I used the tin foil/ aceton method to get rid of the bits on my brush, then gently removed it using orange woodstick. It worked for the next 2 client, then happened again..I got really upset, til i found out what happened. Im working from home, my salon is in a conservatry, my table was next to a big window, even the rooftop is glass. The thing is girls, the sun DOES damages the brush! I moved my table to the only corner surrounded by walls, no window, all day long in the (kinda) shade, but definetely NO SUN...Since then, i did gelish for 6 client, and ABSOLUTELY NO PROBLEM with the brush!! Ps. with shellac you will never have the problem, since thats a polish (hibrid polish) not like gelish wich is a coloured gel (nothing to do with polish!) Shellac is more like heat sensitive, it goes thick, creamy with time, especially in the summer. Hope i could help, and sorry for my english (im hungarian)