Recommendation? Silicon Carbide vs. Aluminum Oxide loose grit FLATTENING / DRESSING / LAPPING guidance needed!

[EDCJourneys]

Hey hey everybody!

So I’ve only recently started to run into the need to flatten, dress, lap stones.

I’ve always managed with a concrete brick, sidewalk, nagura, etc. all depending on the stone of course.

As my collection of stones (and types) has grow, my knife collection / need to sharpen has increased drastically…. OK… all that preamble to explain why I need to get schooled on something you probably will think is elementary! …

I am wanted to move into the loose grit methods. I have a cheesy glass to use for now. I do not have a flattening stone presently. I do want to get a solid one though. Soon. But not today!….
-I HAD a supply of 60 grit silicon carbide,
I realize it’s pretty much the go to material for the first step(s) in the process..
-So, that said… I ultimately will get some again…
…I am at least aware enough to know it’s brittle, grows finer in grit as you go at it with the stone, and I know I’ve seen people mixing grits, and bring it up to a point of dressing they like on the stone in question…..

OK!…. So here’s where I start actually needing some guidance from you pros!

With my silicon carbide MIA, I happened to have a supple of 240 grit aluminum oxide ready to go. Idea originally was to step up to this as a finishing-ish, grit

So here it is:
Is 240 grit AO too fine to start with?
I am specifically looking at an “old vein” antique Washita oil stone today.
I’m curious about all my stones…but the Washita is what’s on todays docket

If the 240 ao is as I think and not going to dent this to start with….
what can I start with,, aside from SC loose AND SC flattening plate, to get this going ?
Maybe I should use my good ol concrete brick and. Water to flatten…then move on?

That’s part 1. Let’s assume I get it flat with what you tell me…

Would the 240AO be a good place to bring it to? Is that too much, too little?

And the part where I’m really really looking to learn in is:
What are the actual use cases for AO vs SC?
Do certain stones respond better or worse to one or the other!?

If a flattening plate is my next purchase…what loose grit material would I be most interested in?
My collection of stones ranges from Japanese water stones of all qualities to ceramics to natural oil stones to the good old crystolon etc.
my largest area of need for these things is the natural stones that re so hard.

I know I am typing too much for this question but I wanted whoever does see this to know as much as I could provide about the situation and supplies.

If there’s further ?s just let me know!
AND THANKs to anyone who reads all this and especially to any replies!

Bob
EDC Journeys

 

[FortyTwoBlades]

The aluminum oxide will work for that use case but will probably be a bit fine. Aluminum oxide is only a little softer than silicon carbide and a decent amount tougher, though much depends on the specific grade of the material.

 

[eKretz]

I like a grit more like 120 when using SiC loose grit to surface a Washita. I want the stone to cut fast. 240 grit in AlOx may or may not give a surface near equivalent to that since it doesn't break down like SiC does during use, but I can't say for sure. I think I concur with 42 that it may be a bit too fine for my liking. Try it and see if you like the result... As 42 says, the SiC grit is much more friable than AlOx so it fractures and basically changes to a finer grit in use. AlOx should be a good bit more resistant to that but will cut a little slower since it's not as hard as SiC.