Mirror Polish tricks and tips?

theWeatherman

Well-Known Member
I was wondering if you guys had any good tricks and tips about getting a mirror polish?

I use my Craftsman 2x42 up to 400 and then start by hand and a sanding stick. I have the hardest time getting scratches out from the previous grits. It takes me longer to finish and polish than it takes to do everything else and I never can get a mirror polish even going up to 2000 and then using 3M polishing papers. I mean, I can get parts of the knife to look ok but there are still scratches and I can sand for 3 hours with 800 grit just to get out most of the 400 scratches, never all of them. There probably is scratches for lower grits from my belts as well. I tried even going to 400 on the belts then stepping down to 220 with my hands and sanding stick.

I use O-1.

Help Please!!!
 
Give Rhynowet paper a try, its helped me with this issue. I use it with windex on the lower grits and mineral oil on grits over 400.
 
Hi,
Are you changing directions with each new grit?
This is very important to sand length ways with the 400G and then go the opposite way with the 600 or 800G you are using. If any scratches show? go back to the previous grit and rework it.

Good Luck.

Laurence

www.rhinoknives.com/
 
Get yourself a very fine scotchbrite belt.
I grind to 400 grit, give a few passes with the scotchbrite. This will show you any canyons you missed. Sometimes a couple passes at 220 grit gets you back on track. Try it again when you finish another 400 grit pass. Why waste your time and paper at higher grits only to find big scratches. I sometimes hit the buffer with white compound for a minute after the scotchbrite, bad scratches really pop up in the bright blade. If all is good, then I'll start hand sanding at 320 grit and it goes quickly from there to 2500 grit. Between the scotchbrite and a quick buff, you're only investing about 5 minutes compared to possible hours of hand sanding.

If you click on the link below...the two military build knives were finished with the scotchbrite belt after 600 grit.

Rudy
 
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When I sand by hand I switch directions, however when I am using my grinder and doing the flats to 400G I go long ways with the knife. I haven't found belts that work very well with my Craftsman 2 x 42 grinder that don't get jumpy after 220G, so that could be a problem as well.

I haven't seen a scotch bright belt for the Craftsman 2 x 42. Do you guys have suggestions for making the belts go smoother and not get jumpy after 220 grit?
 
Try the Gators, Trugrit has them up to 600 for the 2x42, which is a lot easier to start from for a mirror finish. They don't hop. I grind my blade, get to 120 with ceramics, cleanup the plunge with a 120 grit jflex, then switch to the a100 gator and work my way to the A30. They don't GRIND as well as ceramics, but they do an excellent job creating a clean finish. Just a couple passes per grit generally, or you'll see where things weren't flat real fast and can fix it.
 
I'd add that it's worth starting with coarser sandpaper when hand sanding. I usually take it up to 400 or so on my 2x42, then drop back down to 220 for hand sanding. I find this helps get everything flatter in case there was some unevenness left from the grinder. The Craftsman goes so fast that the finer grits make me really nervous. It's also worth going back down a grit level if necessary to get out some scratches you missed. You can sand all day with 1000 grit to get out those 400 grit scratches you missed. It'll save you time and paper to go back down to 400, then 600, then 800 rather than trying to get 'em out at the end.

Also, I use a squirt of WD 40 together with a few drops of Mobil 1 as "cutting fluid" while polishing. It helps a lot, and both together is better than either apart.
 
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I am going to try all of these out to see which works best for me in my work flow. I haven't used any "fluid" for sanding so that is top on my list.
 
Another thing to remember, is that before you can get the scratches out, your work must be flat so your paper can cut them out. By that I mean that if you have a slight dip, from grinding, in your blade, and you go to your hand sanding with a stiff sanding stick, your paper will float across the dip and not touch the scratches in the bottom of the dip, so until you get those very slight dips and valleys out, by hand sanding, you will have scratches. So by being as precise as you can on the grinder, making flat areas truly flat will help when you go to hand sanding.

So what I do is go back to 320 grit to start my hand sanding, and run lengthwise of the blade until all scratches from the grinder are gone, then go to 400, and go across the blade, then 600 lengthwise, and go on up through the grits. At 600 grit you should start to see a dull mirror look to the finish. I hope this makes sense, and helps out.
Dale
 
I'm a lot like you, I can always find those unexpected "character marks" when it's supposed to be a mirror finish. Something that seems to have helped me is to wet-sand the blade. I'm thinking/hoping that the water removes the swarf (I think is the term) so that it can't cause unwanted scratches. My last three or four blades I did in the kitchen sink (yet one more thing to get yelled at for) with an inch or two of water and just a little bit of dish soap. After working up to 1500 or 2000 grit I use a metal polish to bring out the shine. It was just a tube of some kind I had laying around. I bought some Brasso but it doesn't work on steel I guess. I don't have a buffer.

- Paul Meske
 
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