I have an amber Fuller brush that I would like to repair/re-knot. The knot that is in there is in poor condition and worn out. I really just wanted to warm the brush in hot water until the glue loosened, but that does not seem to be working. Two questions, what did fuller use for bristles - these are very soft and appear to be real; and the knot seems very small in diameter when compared to the modern brush I am using. Should that be a concern?