Fishwhipped,
What do you mean by "...the flour usually cuts through...?" Are you saying the fluorocarbon is actually slicing through the monofilament? If that's actually the case, I think the only cause can be a too loosly tied knot that results in the fluoro slipping.
A fluoro to mono connection using a double (4 turn) surgeon's knot should yield a 100% connection. When using fluorocarbon, its VERY important to draw the knot down EXTREMELY tight and hold it there for a few seconds. Seems there are two schools of thought on tightening with fluoro...(1) draw the knot down slowly or (2) jerk the knot down quickly. Not sure which is best or if there is truly a difference. I draw down somwhat slowly to ensure the wraps align properly as do most folks since we've all been warned of the dangers of heat from friction on the fluoro. Regardless, lubrication is essential; "soaking" the knot before drawing it tight might be a better description over simply wetting" when it comes to lubricating fluoro. I actually submerge my fluoro knots in water for a few seconds before tightening them which may be an extreme.
Consider trying a loop-to-loop connection for tippet to leader using a Kreh (no-slip) loop or a Perfection loop on the leader and a double (4 turn) Surgeon's loop on your tippets. This, too, should result in a 100% connection and allows replacing the tippet without sacrificing leader length; it alwo allows rapid changing of tippets without having to worry about tying connection knots. By tying loops in your various sized tippet material beforehand and sticking them into a leader wallet, the only knot you'll have to tie in the field will be to attach the fly. Additional bene is your tippets can all be cut to the same length. "
By the way, a Palomar knot to attach flies is also a 100% connection (even with fluorocarbon) and is quick as well as easy to tie.
Greg