When working as groomer I did way more "de-shedding" than I ever wished for lol..... I was coughing up fur balls lol....
Sometimes I got in dogs with sooooo much coat and that were so little cared for by the owner, so I had to spend several hours de-shedding. Usually if they were not matted, I started with a regular slicker brush, just to go through the coat, then started from the back and worked my way to the front, lifting a little bit at the time, with a undercoat/underwool rake or comb. That usually gives you a trashbag full of hair. Then a warm bath, with at least two shampoos, towel dry and then while blow drying use the slicker brush and undercoat rake again. When dry they are ready to enter the coach, and mommy does not have to have a fit lol...
Hope you can get some use of this.
Marit