Thread: Creating a slurry

For what it's worth, as I'm a newbie honer too, the slurry cuts WAY faster. I've experimented with honing on dry blue and yellow, then with slurry, with fast results with the slurry. I used to think this whole slurry business was just weird, but I'm a believer now.

Sharpening with only water will create a tiny amount of slurry anyway. The more slurry you create, the better the cutting. It's proportional.

If my razor already has a good edge and I only want to prolong its shaving lifespan before the next honing session, I might give it 20 or so laps with only water.

If I have just set a bevel on a DMT1200 > Belgian Blue then I will create plenty of slurry on my coticule to get it closer to the 6000-8000 grit that the blue is. Then progress to using it with water and then finally my own little tip of using the coticule dry just before stropping.

You could think of it as - a coticule with slurry @ 10,000 grit and with only water @ 12,000 grit. Of course these figures are just used to create a picture.

Hope this helps.

I pretty much agree with everything that poona posted, but I have two minor disagreements. My coticule is hard enough that it generates no slurry when used with plain water unless I use TONS of pressure. I think this varies from stone to stone.

Also, I find the coticule with a heavy slurry will sometimes just completely dull an edge. If there is a small problem with the edge, like a dull spot that I missed on the DMT, I'll sometimes whip up a slurry on the coticule and hone just that spot with back-and-forth strokes and a little pressure. This takes off metal very fast, sometimes I think almost as fast as the DMT 1200. The slurry gets black.

Usually at this point I find the edge is properly set but it seems really dull--it won't shave arm hair at all. Dropping back to the Belgian blue for a few laps has it popping hairs again without trouble. I don't understand why this happens, but I've seen it over and over.

To address your original question, the only reason I can see for not using a second coticule to raise a slurry is that you're wearing out an expensive hone. A cotigura is pretty cheap--$15 or so--and lets you save your coticule for actual honing. But then again, it'll still probably outlast you by a couple hundred years...

Josh

I must get a pic up of my cotigura. It is almost double sided. One side is quite a light shade of brown/red and the other is the normal yellow.

Yours the same?

Mine is the same color all the way through--creamy yellow.

Josh

I agree with Josh here, be careful not to create a
slurry that is too heavy -- I've also found that it
can dull razors. A nice light slurry from a few strokes
of the cotigura is just the ticket!

- Scott

Originally Posted by JoshEarl

I pretty much agree with everything that poona posted, but I have two minor disagreements. My coticule is hard enough that it generates no slurry when used with plain water unless I use TONS of pressure. I think this varies from stone to stone.

That's exactly my experience. I have worked with 3 different coticules. One created slurry out of his own very easily. The second did not create slurry on his own, not even after an extended time of honing. The third was similar to the second, but after extended honing a very thin slurry would emerge.

Originally Posted by JoshEarl

Usually at this point I find the edge is properly set but it seems really dull--it won't shave arm hair at all. Dropping back to the Belgian blue for a few laps has it popping hairs again without trouble. I don't understand why this happens, but I've seen it over and over.

My theory about this is that a dense slurry abrades the very tip of the bevel as you push the razor through it. (It's a bit like pushing the edge of a knife through mud, IMHO) Of course, after the heavy work, a bit of honing with a thin slurry will get the edge keen again, so if you're without a bevel-setting stone, I think a dense slurry could be worth trying. I have one question, though. I fear that heavy pressure in conjunction with a full hollow ground razor might flex the bevel a bit. I reckon it will flex back on it's own, but while being flexed, the honing angle is actually altered. I have no idea how that would affect the honing results.

just a few additional thoughts,

Bart.

Bart,

I like the mud analogy. The thing I don't get is why a heavy slurry on the blue doesn't have the same effect. Maybe because it cuts slower?

Josh

I've had different results on different coticules as well.

As for creating slurry on the blue, I don't it automatically appears when honing for me. The blue seems soft enough that I don't need to do anything about it.

Originally Posted by JoshEarl

Bart,

I like the mud analogy. The thing I don't get is why a heavy slurry on the blue doesn't have the same effect. Maybe because it cuts slower?

Josh

Actually my blue does it too. Only a few days ago, I decided to finally tackle a Friodur that has been lying around here and never really quite got up to par. I put it on the DMT and lapped till I was absolutely sure the bevel was excellent. Great results on the TNT and TPT. I stropped it a little and it mowed arm hairs above level and passed the HHT. Actually my most promising result off the DMT so far. Then I created slurry on the blue. I overdid it a little. That blue produces a slurry very rapidly. I added some more water to dilute it, but still, while I was honing I was telling myself "this is too dense a slurry", but I continued anyway. (You know how good we humans are at ignoring the obvious). I did about 50 laps. After that the results on all test were negative. I went back to the DMT. It took me about 10 light laps to get back at were I was before the blue again. I rinsed the blue and made sure I had a lighter slurry this time (that first slurry had the consistency of coffee cream - while now it was more like watery milk) I did pretty much the same 50 laps, and stayed on track this time. Finished on the coticule and had a superb test shave.
So maybe there's variation in the blue stone too. After all, they are naturals...
I have another blue, that I haven't used much yet. A big heavy F.Herder (1/4 ground - curved spine) is anxiously waiting in the drawer to get honed. I'll put it on that other blue and see how that one behaves.

PS. A sudden strike: Like others, I create the slurry on the blue with a small piece of yellow coticule, so half of the slurry consists out of yellow particles. That might make all the difference.

Bart.