For the benefit of us new to the effort, can you who are many much more experienced (regardless of this possibly having been gone over countless other times) discuss stropping technique rather than just saying that what we have here is a stropping problem?
I'll take a shot at this as its early and I don't want to do my homework right now. Damn college. Anyway, in my opinion.
Does one pull as hard as one can on the strop to absolutely minimize sag?
Yes, but pulling "hard" is often overkill if your not going to use pressure. There is a relationship between how hard you need to pull and how much pressure you can then use. One should guard against sagging.
Does one let the strop sag somewhat? What is a reasonable droop?
No, but a little sagging will often both slightly dull the edge and roll it inward, which isn't always a bad thing. In very, very rare instances you want the edge to roll inward a little. Generally, no droop is called for.
Does one push and pull the razor on the stop with absolutley no pressure, if not, what amount of pressure should be used and how can one judge this force?
The pressure used is in relation to what your doing and how the strop is treated. The measure you use is to feel a little draw, this tells you your achieving the objective of aligning whatever fin might exist, small or "large". If you have a strop treated with a heavy sticky material, hold the strop really taught and use lots and lots of pressure you'll sometimes tear at the fin.
Using more than a light draw is often overkill.
If you have a strop treated with a light "slick" compound like EVVO oil (as I do) you'll not have as much draw and you can get away with more pressure.
A multitude of factors effect pressure: 1) How stiff is your strop 2) the treatment on the strop 3) the grind of the blade 4) the sharpness of the edge
So let me pontificate (my opinions only of course) on these 4 issues
1) A heavy stiff strop will not bend as much and will more likely roll the edge so lighter pressure is called for, I think they lean a little more towards being less sticky by nature too. I can use lots of pressure on my strop but I have to compensate with lots of taughtness (thank god I spend time in the gym). Then again, in some ways a heavy strop remains "stiff" on its own somewhat too and its natural stiffness can actual prevent sag.
2) Treat a strop with a compound that creates draw and you should use less pressure, its a simple enough concept actually. Apply a sticky fat or say, stiff lather to a strop and its effect on the edge is magnified, this can be good (with less pressure) or bad (with too much pressure).
3) Full hollow prefers less pressure, again its simple physics, a wedge can stand a little more pressure. Generally though, I wouldn't rely on the grind to support the edge against a strop, because the action of the strop is focused on the edge. Regardless of how taught you hold a strop there is a little tiny bit of sag at the edge where the razor is touching into the strop. It can be caused by compression or an actual bend between the contact of the edge and the point past the contact. The grind is more a protection against the user applying too much pressure into the spine area as a wider grind supports against the maniac that is pushing the blade into the strop.
4) A sharp edge has a finer fin and tears more easily. In a perfect world your starting out using very, very light pressure. Into the end of the month I use more pressure and more linen action to keep the edge going.
Does one avoid putting any dressing or compound on the hanging leather strop?
Its debatable what "one" should do. You need to treat the strop. The best method is with some kind of light oil or fat. I think rubbing the strop with your hand is the perfect method. I apply EVVO oil as I mentioned (because I"m impatient and don't actually like messing with all this stuff). I can use a sticky fat like they sell at classic shaving too, but then I'm more careful when I'm stropping a sharp/newly honed edge.
How does one determine if the hanging strop requires dressing and then what should be used and in what quantity and with what method of application?
If the strop becomes dry, brittle, or fails to produce any draw at all because of a glaze then treatment is probably called for. As everyone has probably figured out, leather, by its very nature, draws on the bevel of the steel and aligns any problems. Its better to be conservative on treatment with modern strops.
I think I'm in the minority here, but I find stropping, though important, overdone. I often shave without stropping at all. I often only strop 10 passes. Just like honing, I'd rather be cautious and re-strop rather than blow the edge
The best stropping I've ever done though has been on a well supported paddle strop using pressure. I have aligned the worst edges using a strop alone. That being said, for everyday use a hanging strop, held taught, treated only with EVVO oil or natural skin oils works great. When a strop treated like this does draw then I know the edge is really sharp. If I had a compound to make a strop draw then I'm missing the feedback, but the draw can produce its own sharp, smooth edge too.
So we end up with a YMMV (your mileage may vary) problem. I bet we have more strops on this forum then members and each is a little different. Just as with honing, there is also more than one way to effectively strop.
I apoligize now to the moderators if this is a little overboard for the Newbie section.