There's definitely a difference between cutting and polishing. Last night I finished cleaning up my mil-build knives (pre-HT) with 220 and plain water. I can't swear to it but it does seem to cut a little faster that way. Then I switched back to Mobil1 and 400 grit, and I still like the way it polishes. I'll continue to try different "lubes" at different grits and see how they work.
In the meantime, I've been using plain unscented food-grade mineral oil to protect carbon blades from rust for a couple years now. It doesn't stink, won't make you sick and doesn't eat up leather. I never thought to try it as a sanding helper!
I completely agree there's a difference between cutting and polishing.
I must admit that it's been quite some time since I've comepletely hand sanded a blade, but I certainly remember what worked best whenever a customer brought a rough casting into the shop. Someone putting an intake manifold or a set of wheels or the like at your doorstep will certainly have you thinking about how you're gonna approach it.
We would start by using a
greaseless compound on a buffing wheel. This is available in various grits from 80 up to 600. The wheel is initially prepped with a "glue", then the greaseless compound is applied to the wheel just like a regular buffing compound.
Essentially, you now have a very flexible abrasive capable of quick cutting. Better than J-weight paper on steroids, and instantly rechargeable.
Now consider the final stages for polishing. The buffing compounds have grease binders in various degrees.
Different purposes, different binders. I don't know about anyone else, but I'll apply the same concept to fluids used in hand sanding.
Am I wanting the swarf to get out of the way so the abrasive can do its job (cutting), or am I wanting to keep it in suspension?
If I'm removing larger amounts of material, I want that stuff out of the way. If I'm polishing, I want that stuff in suspension because it continues to be ground finer and finer, providing the polishing effect.
I'm making another chef's knife, and my daughter is gonna help me finish it. This is her first go at the finishing process, so she's gonna learn how to do a mirror polish by hand. It's at 220 out of HT, so we'll start there and work our way up.
Water, windex, etc. until we get to 400 (maybe even 600), then switch to oil. Might give the Mobil 1 a try, but I'm also sittin' on close to 10 gallons of lightweight food grade mineral oil. We'll see what happens.
Rob