'Ghost' scratches/sub-shine abrasive marks on a polished finish - is any level it acceptable in a finished knife?

[FloWolF]

Just as per the title - is there an acceptable amount of visual artifact relating to early grit grinding, that is generally 'acceptable' showing up through a polished finish?...

Cheers me dears!

Shaun/FloWolF

 

[bsfsu]

Acceptable is a fairly variable opinion.

Acceptable for what price range/maker?

What knife of finish? A full mirror polish is a bit different to a sand blasted KU kasumi.

Hand or machine finish?

Also what kind of scratches? An even scratch pattern might be the finish the maker was after?

The quality control of makers varies, if is it acceptable to the maker/supplier/knife shop should it be acceptable to the final customer?

I'm sure in some cases it's acceptable, maybe not in others.......

 

[FloWolF]

Acceptable is a fairly variable opinion.

Acceptable for what price range/maker?

What knife of finish? A full mirror polish is a bit different to a sand blasted KU kasumi.

Hand or machine finish?

Also what kind of scratches? An even scratch pattern might be the finish the maker was after?

The quality control of makers varies, if is it acceptable to the maker/supplier/knife shop should it be acceptable to the final customer?

I'm sure in some cases it's acceptable, maybe not in others.......

Thanks for the reply.

The whole story - The knives in question are my own makes.

I find I struggle to remove all the signs of the previous grade abrasive with subsequent finer grades, and it's only really becoming evident as it moves through the finer grades towards the polishing stages.

On some knives it's not so bad, and a good satin/satine or similar finish does the trick.

However I'm now on some knives that are very hard (64HRC, a petty in Wolfram Special and Gyuto and Santoku in Sheffcut). The later 2 have a hamon cooked in, and so definitely need a good smooth finish to bring that out, and I want the finish of the petty to match.

However I can't get rid of the underlying abrasion marks, and I'm going to run out of knife if I'm not careful.
I'm starting with Cubitron 984F (I think) and stopping at 120g, switching to Trizact 120g, then working up the grades with the trizact belts but I'm just not getting where I'm aiming at and end up reintroducing new defects in the process.

I don't know, maybe I'm secretly drunk off my arse or something, (Actually a decade 100% sober, but there ya go.)

Cheers me dears,

Shaun/FloWolF

 

[Skylar303]

I don't polish knives but I do cut and facet stones. What you're describing happens when I don't fully remove all the scratches from the previous grit. And the problem only becomes more evident as you go higher in grits.

Ex. I'll shape with a 260 grit, then move to a 600 wheel. If I don't clean all the 260 with the 600 and proceed to 1200/3000 there will be deeper scratches left from the 260 that are really a pain to "buff out" essentially at the higher grits.

Idk maybe some of that translates over to the progressions with stone/belt grits as well?

 

[FloWolF]

I don't polish knives but I do cut and facet stones. What you're describing happens when I don't fully remove all the scratches from the previous grit. And the problem only becomes more evident as you go higher in grits.

Ex. I'll shape with a 260 grit, then move to a 600 wheel. If I don't clean all the 260 with the 600 and proceed to 1200/3000 there will be deeper scratches left from the 260 that are really a pain to "buff out" essentially at the higher grits.

Idk maybe some of that translates over to the progressions with stone/belt grits as well?

Oh yes, this is definitely my issue, just this time it's been much worse and with the hardness and quality of these steels I'm struggling to a) avoid it and b) make it go away when I discover it.

I think I created the issue early on with the 36 and 60 grits, since the steel was very hard and needed a lot of thinning to start with.

I feel I need some hand abrasives that are hard enough for the steel to finish off with but my carbide w&d papers hardly touch these steels even with a hard backing.

For a bit further context I feel I need to blurt that I'm adhd/autistic, and my symptoms have been off the charts this last few years and this is seriously compromising how my experience interacts with what I'm doing - I 'misplace' my knowledge and experience all the time, so I miss tons of things I shouldn't, and didn't used to miss. Lots of chaos has entered my process!

Cheers folks,

Shaun.

 

[ta2edfreak]

Get some EDM polishing stones and switch to those after the 120/220. You can apply pressure differently and create your own shapes to get into tricky spots. Falcon has some good sets and Gesswein sells them as well. Once you get a hazy finish with them, you can see where your bigger scratches are and maybe step back a grit. go as high as you want then finish with paper or diamond.

 

[Tekkz]

I don't polish knives but I do cut and facet stones. What you're describing happens when I don't fully remove all the scratches from the previous grit. And the problem only becomes more evident as you go higher in grits.

Ex. I'll shape with a 260 grit, then move to a 600 wheel. If I don't clean all the 260 with the 600 and proceed to 1200/3000 there will be deeper scratches left from the 260 that are really a pain to "buff out" essentially at the higher grits.

Idk maybe some of that translates over to the progressions with stone/belt grits as well?

Ayyyy another gem guy! I do both. The exact same principles apply to rocks and steel.

 

[FloWolF]

Ayyyy another gem guy! I do both. The exact same principles apply to rocks and steel.

Funnily enough I'm also a jeweler, although I don't cut my own stones. However I've sanded and polished enough silver, and cabbed enough resin/stabilised wood pieces, that I know how it goes with scratch removal>polishing for most semi-hard and hard materials.

It's not helping me much with these knives though those steels at 64HRC and so stupidly surface-tough and my experience isn't translating over well

 

[MSicardCutlery]

My progression is 36>120>220>scotchbrite or 320 grit rhynowet. A smaller gap between grits make removing the previous scratches easier, yes, but it also makes differentiating between the two more difficult. Alternating tilting the piece 5 degrees off of vertical and dead vertical between grits will help with that too.

Edit.

SheffCut is not much different to work than hard 52100/26c3/W2 or 1095. Apex Ultra is a little harder, but not too bad. Wolfram special is ******* awful for what it is though. Worse than Apex Ultra, and I have compared the two side by side. It grinds almost like Zwear. I don't plan to use it outside of san-mai because of that. What you're experiencing with SheffCut is basically typical of low alloy steels though.

 

[H*3=ME]

Thanks for the reply.

The whole story - The knives in question are my own makes.

I find I struggle to remove all the signs of the previous grade abrasive with subsequent finer grades, and it's only really becoming evident as it moves through the finer grades towards the polishing stages.

On some knives it's not so bad, and a good satin/satine or similar finish does the trick.

However I'm now on some knives that are very hard (64HRC, a petty in Wolfram Special and Gyuto and Santoku in Sheffcut). The later 2 have a hamon cooked in, and so definitely need a good smooth finish to bring that out, and I want the finish of the petty to match.

However I can't get rid of the underlying abrasion marks, and I'm going to run out of knife if I'm not careful.
I'm starting with Cubitron 984F (I think) and stopping at 120g, switching to Trizact 120g, then working up the grades with the trizact belts but I'm just not getting where I'm aiming at and end up reintroducing new defects in the process.

I don't know, maybe I'm secretly drunk off my arse or something, (Actually a decade 100% sober, but there ya go.)

Cheers me dears,

Shaun/FloWolF

from my experience bringing a gyuto up to damn near mirror finish, i only brought it up to 120 with a 2/72 grinder and then moved into norax belts, starting at x65 (220) x45(320) and finishing on the sander at x30 which is 600. those belts are amazing at their job and then i move off the belt to good ole fashion hand sanding with a few pieces of sand paper and a jig to hold my blade at each step in to process looking for scratches in sunlight, and then its smooth sailing after i get a good 400 base hand sanding all the way to as high as a grit you have. hope this helps! im also working with 62cr high carbon 1080/nickle damascus.