'True' mirror polish...by hand. Possible??

T

Toddman214

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Feb 23, 2023
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Hi all. I'm customizing an existing knive (my own), and I've reached a point at which I've polished the blade (m390) to a wet-sanded 10,000 grit, and then hit it with Flitz which I think actually very slightly dulled it. I think Flitz is like 3micros or so. Anyway, I'm as far as I can get, but I'm trying to get to the similar 'true' mirror surfacing as the Microtech Marfione customs. I do not own any sort of belted knife making equipment, but I want this to be a very high-end finish. I have several levels of TechDiamond
paste, 1200 through 100,000 grit. These should get me there, but im not sure of the best method, to get that true mirrored flat grind that I want. Do I just finger rub these, rub the blade against the paste on my glass platten, other?

Thanks all!
 
That sounds like a lot of work, but I would put light paste on printer paper then rub that on the blade, and progress to finer grits only when it looks perfect at the lower grit
 
Flatsman007 said:
Jewelers rouge on a piece of cotton and hand rub.
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Yep, but try hard not to rub in circles or concentrate too much on one area. Swirl marks ruin a high-polish finish. Ideally, you want to run your strokes the whole length of the blade evenly, back and forth.

Once you start approaching something that comes close to a mirror finish, any smaller areas that are worked too much become very apparent, and ruin what you are trying to achieve. Again, full length blade strokes.

Change your lighting angle frequently to ensure you are getting a uniform polish.

You may want to Google "How to polish katanas". There is a lot of good information on the traditional method of hand polishing to a super mirror finish.

Good luck.
 
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fishface5 said:
That sounds like a lot of work, but I would put light paste on printer paper then rub that on the blade, and progress to finer grits only when it looks perfect at the lower grit
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I dont mind the work. So far, I've taken the factory stone wash off the blade, and worked all of the tooling marks out of the m390, starting with 320 grit, moving slowly up through 10,000, cross-hatching over the previous grit pattern, using only tiny peices of sandpaper, on the tip of a bamboo stick. My fingers are toast! This is a dagger blade in a Microtech Glykon. Once I passed 3000 grit, it started sanding only along the blade length.
 
Flatsman007 said:
Jewelers rouge on a piece of cotton and hand rub.
Click to expand...
Oops...I left something out of my sentence. I have 1200 through 100,000 grit DiamondTech paste 'on the way'. I dont have it yet. Was just wondering about best way to apply that. I think the finest jewelers rouge comes in with a grit size of around 2 microns, or about 13,000 grit.
 
I don't know that I'd try it on the mt but I'd try a dremel on lower speed and the little polish wheel. It might be hard to get an even finish with that but if you hand finish the last of it. I think for the perfect mirror you want to use as many grits as possible or spend a long time with every grit to get out what the previous one left behind. I'm not sure but I have to guess the good mirror finished knives are done on a polisher? Probably a big cotton wheel for a tormek kinda thing. I don't think it matters what you appliy it with as long as it's clean. Cotton isn't gonna scratch that m390.

Edit. I'm assuming your cleaning the knife and starting with a new cloth or something to apply the next one when you work up in grits. M390 can scratch M390 and if those coarser grits are there still you won't progress much.
 
Oh, yeah. I'm avoiding the cross contaminants. Many people would look at the blade as it is right now, and think, "oh, that looks really nice". I'm near-sighted and picky as hell, so I see everything. If it ever leaves my hands to a buyer, I just want it to be perfect.
 
And what about haziness? I've gotten my blade pretty much 100% of what a 10,000 grit wetsand, pink rouge, or flitz, can do. It has a haze to the finish, but is nearly glass smooth.
 
Toddman214 said:
And what about haziness? I've gotten my blade pretty much 100% of what a 10,000 grit wetsand, pink rouge, or flitz, can do. It has a haze to the finish, but is nearly glass smooth.
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Haziness is sometimes due to the inability of the polishing compound to cut or fully polish the hard carbides in the steel. This also means edge sharpness will fall somewhat short of its best as well, if an inadequate compound is used for stropping such a steel.

M390 does have some vanadium carbide content - those carbides will be harder than the aluminum oxide used in the polishing compound. So the AlOx will fall short of fully polishing those carbides. Anything with 3-4% or more vanadium - with M390 at 4% - would benefit from using diamond or cbn compounds instead.
 
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Thank you. I still have a set of TechDiamonds 50% concentration, 1200 thru 100,000 grit pastes on the way to me. I've heard good things about these, working with these harder steels.
 
mirror-polishing task. At a late point down the line it will become easy to over-polish a flat area. To me, that's the hardest aspect or say most frustrating aspect. The 2 related natural phenomena are called 1) micro-pitting, and 2) burnishing, and both can occur, and they are quite impossible to control. Doctoral PhD thesis pdf's on this topic can be googled, sponsored by unis and comps in that industry. The existence of such PhD doctoral thesis is proof that mankind hasn't figured out yet how to control the two in a guaranteed straight-forward manner. Good luck with not running into either phenomenon or both.

back to OP. 'true' mirror polish isn't possible by hand or similar abrasive methods. Just think backwards, start with a true mirror finish made out of metal, say the discs from an old hard drive (HDD): these are the most pristine and deepest true mirror finishes man has ever made. Then rub the mirror surface with a rag and 0.5micron diamond paste. now you got a scratched mirror. bam. (and with a flashlight and the correct lighting and viewing angles you'll be able to see those 0.5micron wide scratch lines/swirls, with your naked eyes!)

As i wrote in other similar threads, for an amateur/beginner the easiest mirror polishing task (as a starter, for practice) would be a wire pocket clip or a lanyard bead. These small objects have no flat areas and are not prone to develop those 2 phenomena.

kreisl? out. sorry.
 
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I typically get my blades to a 120 belt finish and then start on the sandpaper. If you go at a 45 degree angle up the blade with one grit such as 120 and then go at an opposite 45 with your next grit, i think you will have the best results. Just remember to sand at an angle until all the grit scratches from thee other angle are gone. using water can help cut it faster. this will make sure you dont have any scratches. I just go up to 2000 grit and it looks great. then when i am done i like to hit it with some polishing compound and buff anything out. Good luck.
 
Thank you, Raider. My main problem is that I can get to a mirror finish. As in, can stand outside and clearly see the bricks in my neighbors house in the blade. But, when I turn the blade just right, there is a persistent haziness that I am fighting. I know that m390 and Magnacut are capable of a true mirror finish. I just saw examples at the knife show, where these were polished so well, they looked black from an angle. Maybe they are using a brand new polishing wheel for each knife? I just don't know.
 
kreisler said:
mirror-polishing task. At a late point down the line it will become easy to over-polish a flat area. To me, that's the hardest aspect or say most frustrating aspect. The 2 related natural phenomena are called 1) micro-pitting, and 2) burnishing, and both can occur, and they are quite impossible to control. Doctoral PhD thesis pdf's on this topic can be googled, sponsored by unis and comps in that industry. The existence of such PhD doctoral thesis is proof that mankind hasn't figured out yet how to control the two in a guaranteed straight-forward manner. Good luck with not running into either phenomenon or both.

back to OP. 'true' mirror polish isn't possible by hand or similar abrasive methods. Just think backwards, start with a true mirror finish made out of metal, say the discs from an old hard drive (HDD): these are the most pristine and deepest true mirror finishes man has ever made. Then rub the mirror surface with a rag and 0.5micron diamond paste. now you got a scratched mirror. bam. (and with a flashlight and the correct lighting and viewing angles you'll be able to see those 0.5micron wide scratch lines/swirls, with your naked eyes!)

As i wrote in other similar threads, for an amateur/beginner the easiest mirror polishing task (as a starter, for practice) would be a wire pocket clip or a lanyard bead. These small objects have no flat areas and are not prone to develop those 2 phenomena.

kreisl? out. sorry.
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Kreisler, the hard disk platters are a great example! I though perhaps I've been too hard on myself about my polishing. (What I am mainly asked to polish are high-end OTF and other pocket knives.) But, when I went to the blade show this past weekend, and looked at Marfione blades, and other full customs, the mirror polish is amazing! To the eye, they are similar to what you describe with the hard drive platters, so I know its possible with the steels I'm polishing. I just can't seem to get past a slight haze in the steel.
 
Using a cotton buff without compound will do absolutely nothing to your blade.
If you look at a polished blade under magnification, you will see slurred lines, or ripples rather than scratches. This is where buffing, rather than sanding comes in. The proper buffing compound depends on the steel, and the finish prior to buffing. While you can, at least in theory, truly mirror polish by hand- the polish you use depends on the steel.
 
T Toddman214

my thoughts:

I don't like the glass backing with the pastes.
I don't like your pastes because they don't specify what type of diamond.
Define your sharpening phase by using a diamond "stone", not the pastes. You're probably not cutting the steel well enough and will always have that haze because you're not starting off correctly.
 
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