When I started as a technician in the Orthotic and Prosthetic field I always used a string that did not absorb resin. The string served its purpose, but I ran accross this tip from a technician that does great central fabrication work (Sunstone Lab for those who are curious). The benefit of using a nysert as your string is that it becomes part of your lamination. The results are phenomenal and structurally the lamination now is fully saturated and one piece. The other benefit of using this tip is that your string does not show through the outermost layer of lamination.