As a wood worker I have been sharpening my own tools for a long time. One thing I have learned is that the term "sharp" is relative and means many things to different people. A sharp drywall knife wouldn't cut butter very well but a sharp plane blade or chisel can be used to shave with. For a time I was learning how to cut tissue masks on photos so I could air brush and add artwork. (This was before Photoshop and computers in general but just a little after the invention of the car). Anyway I discovered that I could put a polished edge on an Exacto blade that was 10 times better than the way it came new, out of the package, and in about 2 minutes flat. The blades were sharper and smoother and they didn't tear the tissue. You can do the same thing today using a small piece of 600 grit sandpaper, glued to a sheet of glass and a piece of leather to polish the grooves after. I'll provide a photo later if anyone is interested. I bought a small magnifier to look at the sharp edge and you wouldn't believe how rough looking a new single edge blade looks.
Now that I am officially an amateur artisan baker, I have been trying to find a good way to slash my breads smoothly without leaving a wrinkle or distorting the surface. For me, it seems like it's easier to control a single edge razor held in my hand than anything long or remotely resembling a stick or stirrer. The blade will get snagged in the dough if it's slack enough to be sticky unless you oil it beforehand. I have also had luck using a little water on the blade to help it glide. The speed of the slash seems to help if you can control it.
There also seem to be different schools of thought in regard to how deep to slash. Depending on the hydration level of the dough and the surface tension you have placed on the outer skin, the effect of a shallow slash can be quite different. Some seem to like to go over the slash again making a deep cut (1/2 inch) into the dough which results in a wide gaping valley that may fill in with oven spring. I recently read where it may be advisable to slash whole wheat doughs after the final forming so they proof with the slash and won't later deflate with a last minute slash.
Many of us seem to be having trouble deciding what works best in various situations. For the life of me, I don't get the need for a curved lame. I must be missing something on this one. The one thing I am sure of is that what ever you use it must be sharp (really really sharp)and clean.
I watched a video last week someone posted that showed some bakers in a commercial bakery slashing Baguettes. They were using something small held in the hand and quickly making long slashing movements. Quick and sure strokes. I tried that and it seemed to work for me but maybe a little questionable where the cuts would end.
This would be a good place for a video training aid. One for medium hydration french and another for whole wheat. Any one up for that?