Readily Available Compounds for Polishing to a Mirror Edge

I have a feeling you're not getting all your scratches out before moving to stroping. You're rushing it. Going from 1000 grit stone to polishing compound is way to big of gap. All you're doing is polishing your scratches. You need finer grit stones before moving on to stroping. Off topic, but Clay Allison of Wicked Edge has some awesome pictures of knife blades under a microscope at more than 1000x zoom. It also shows what different grits do to the steel and what it looks like. Just a FYI. If you want to know where to get micron and sun micron diamond sprays just shoot me an email, more than happy to help.
 
Hard to know where to begin :) 1000 grit isn't a mirror edge you would need something more like 5k. Is your goal just something shiny? Just saying something is or isn't a mirror finish doesn't really describe your level of sharpness. A hugh jump in compound to a finer finish isn't an ideal way to do it and some stones or coarser compounds after 1k is a better approach.

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Ken
 
knifenut1013 said:
A 1000 grit stone is not very fine.

Jumping to a ultrafine compound of unknown quality and grit is not helping.

Arkansas stones don't go to extreme levels of finish so several compounds or more stones will be needed in your adventure.

The stuff you get locally is usually for soft metals and will kinda work but nothing like a compound made for sharpening knives. You should look into getting some 1 Micron diamond spray. If you cannot get a mirror edge with 1 Micron diamond spray then everything before needs to be considered.
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Good advice!:thumbup:


I usually don't strop until after at least 8,000 grit stones. If I want a mirror polish, I strop after 15,000 grit.
For milder steels, boron carbide and CrOx work well. For abrasion resistant steels, cubic boron nitride (CBN) and diamond work far more efficiently.
 
Hi All, Don't want to hijack the thread, just a question on the subject - I've been finishing with Simichrome Polish and like the results, but then again I'm no knife maker. It spec sheet says it has 8-10 micron particles, so I'm really amazed that you say 1 micron is used. That's 1/10th the size! Or 10X as shiney, what ever that means. Anyway, the question is - In the lower grits what is the ideal progression - 1000 to 1500 or 2000? 2000 to 3000 or 4000, etc And about what grit is 8-10 micron paste?
 
Realized I should have searched before posting so I searched and got my answer. Can't believe 9 micron is 2000 grit. The Simichrome is much finer finish than the 2000 paper I use. Go figure ..
 
The white compound is actually used in the plating industry for buffing chrome plating burns, so yes, you can get a mirror finish with it; it would be the final step, after the green compound.

If the stuff gunks up your strop, use some neatsfoot oil on it like a solvent and wipe off with a clean rag.
 
I tried using black compound (those that shown by Magnanimous on his videos) on Heavy Handed Washboard (check his signature) followed with white (Autosol) on Balance Strop (by bluntcut), it gives near mirror. Enough for my use.

I guess both are readily available. If not, try sandpaper (wet/dry) 1500 up to 2000 grit, followed with Autosol on leather/cardboard.
 
Yotee said:
Realized I should have searched before posting so I searched and got my answer. Can't believe 9 micron is 2000 grit. The Simichrome is much finer finish than the 2000 paper I use. Go figure ..
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I've long suspected Simichrome's abrasive, even if starting out at 9µ, likely breaks down quickly to much finer particles, in use. Some aluminum oxide abrasives are manufactured with this in mind (friability), and it can be tweaked by the manufacturing process to greater/lesser degree. In retrospect, it seems to make perfect sense for a polishing paste, which is at it's best in it's ability to quickly scrub away oxidation on metals, and then follow with a high-polished finish.

As an aside, the shape of the abrasive particles also makes a difference. A larger particle that's more 'round' in shape won't scrub as hard or dig as deep as a same-sized particle that's equally hard and more jagged in shape.


David
 
Obsessed with Edges said:
I've long suspected Simichrome's abrasive, even if starting out at 9µ, likely breaks down quickly to much finer particles, in use. Some aluminum oxide abrasives are manufactured with this in mind (friability), and it can be tweaked by the manufacturing process to greater/lesser degree. In retrospect, it seems to make perfect sense for a polishing paste, which is at it's best in it's ability to quickly scrub away oxidation on metals, and then follow with a high-polished finish.

As an aside, the shape of the abrasive particles also makes a difference. A larger particle that's more 'round' in shape won't scrub as hard or dig as deep as a same-sized particle that's equally hard and more jagged in shape.


David
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I've noticed this with SiC compounds. The grit that is broken off the surface of a stone is far more jagged than the graded abrasive one gets from a lapidary shop, which is more block shaped. At comparable particle sizes, the graded silicon carbide produces a much higher polish and less toothy edge than most AlumOx grit.
 
Interesting thoughts on Simichrome, Obsessed. I'm new to almost all the information on this forum but man is it interesting. What a great idea - a work mediated, self reducing grit size abrasive. It could conceivably let you jump a few levels in one polishing making things move along quite a bit faster.
 
A single grit compound is difficult to get a true "mirror" edge with. You need to think in terms of your grit progression during the sharpening. If you skip grits in your progression, you can have a heavily scratched edge with a mirror polish in between the scratches...

TedP
 
Yep, I've done that many times in the last few months. Had to go back to 100 grit 2-3 times after trying to short cut to just 400 or 220 and had polished steel between farther apart scratches. Very good lesson in patience this polishing is. (Said in a Yoda voice). Now that I've got pretty true polished steel I see the slight waves in the steel where my file cut just slightly deeper or I was off my line slightly. So polishing just shows everyone even more imperfections! I think I'll take up sand blasting and powder coating stuff.
 
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