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C.Anderson

Polishing Question

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Ok guys...I just finished up a knife for a customer.

 

DSCF2952.jpg

 

DSCF2956.jpg

 

DSCF2959.jpg

 

DSCF2962.jpg

 

Turned out nice enough...but there was a problem, and it's still there.

 

If you look closely, you'll see LOTS of vertical scratches. There are a couple that go in different directions...but the vertical ones are the most apparent. What are they?!?!

 

When I polish a blade after heat treat...the first thing I usually do is bring all surfaces to true on my 1"x30" belt sander. I do this while breaking the edge down to sharp...usually with 36 to 50 grit belts, and very gentle pressure (to keep the heat down). It usually only takes a few passes up the handle to get rid of discoloration and any scale/clay remaining...and most of my time is spent concentrating on the blade. Once that's done, I progress up the grits until the blade is sharp. Then I go back...and brush over the blade horizontally with whatever I feel is an appropriate grit...usually 320 or 400 grit. This brings up any deep vertical scratches (meaning from lower than 320-400 grit) that the belts may have missed (there is almost always some). If they're large enough...I'll drop back down to 120 grit...until they are ALL gone. I then progress through the grits, using block backed sandpaper, until I'm at whatever grit my finish choice requires.

 

This blade was no different. The scratches weren't apparent until I etched the blade...and even then didn't show up until my 3rd or 4th cycle (4:1 water:ferric chloride). Sooo...back to 120 grit (they're clearly large scratches). Go through the process again. NO scratches left...period. Etch, etch, etch, etch...wth?!?! Back to 400 grit (they HAD to be more shallow now right?!)...go up the grits to 1500. Etch, etch, etch....ok...this is BS. Back to 120 grit...go through the process AGAIN. Etch, etch...you get the idea, obviously they're still there. Call the customer, show him the pictures...discuss possible work hardening from the grinder (thus causing the spots to etch darker), alloy banding...etc. He's more than happy with the blade...so I repolish the edge and call it good.

 

Just because he was happy with it, doesn't mean I was. So...any ideas on what this is or how to avoid it in the future?

 

Cris

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can't really make it out on my wee netbook..

-sometimes the etch can make small lines into bigger ones..

and that can be amplified abit by how you sand... if you let the paper get loaded up with cuttings...it'll burnish abit.. .. and the burnish will resist the acid abit more than the scratch ..

 

do you use an oil in the higher grits.. .. myself i use either a canola oil or mineral oil....

 

sometimes its the steel its self... if its not totally homogeneous, some will etch differently....or even stresses put in the steel from grinding

 

if the customer is good with it .. then it should be good... it looks fine to me

 

 

G

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Hey Greg =D,

 

All sanding is done with Windex as a lubricant...or a mix or Windex and the water from the rinse bucket under my sanding station lol.

 

I could definately see burnishing as part of it...but man, I had to have sanded a HUGE amount of material off going back in the grits 4x lol.

 

Ahh well, as you said...the customer is very happy with it, so I have little to complain about lol.

 

Just was wondering if anyone had any idea how to avoid it in the future =D.

 

Cris

 

 

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This blade was no different. The scratches weren't apparent until I etched the blade...and even then didn't show up until my 3rd or 4th cycle (4:1 water:ferric chloride). Sooo...back to 120 grit (they're clearly large scratches). Go through the process again. NO scratches left...period. Etch, etch, etch, etch...wth?!?! Back to 400 grit (they HAD to be more shallow now right?!)...go up the grits to 1500. Etch, etch, etch....ok...this is BS. Back to 120 grit...go through the process AGAIN. Etch, etch...you get the idea, obviously they're still there. Call the customer, show him the pictures...discuss possible work hardening from the grinder (thus causing the spots to etch darker), alloy banding...etc. He's more than happy with the blade...so I repolish the edge and call it good.

I have had blades come out of the etch with "lines" from the trails the bubbles take while traveling up the blade. Did you etch this knife suspended vertically in the ferric? Sometimes it is just the structure of the steel from the mill. Good luck figuring it out!

 

~Bruce~

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I have had blades come out of the etch with "lines" from the trails the bubbles take while traveling up the blade. Did you etch this knife suspended vertically in the ferric? Sometimes it is just the structure of the steel from the mill. Good luck figuring it out!

 

~Bruce~

 

Hey Bruce!

 

This knife was etched point down in the etchant, suspended by the lanyard hole with a bent hanger. The scratches run perpendicular to that direction lol. Hope that takes the confusion about vertical and horizontal out of the equation.

 

I really think this has in some way to do with the 1"x30" belt sander. This blade was forged, bent, shaped...if it were alloy banding (and I considered it...believe me), it would be rather distorted by now I would think. The 'scratches' run from the spine to edge of the blade...in a uniform manner...everywhere they are apparent (which is mostly in the area around the choil...going back up the handle a ways). They seem to be either light scratches with dark surrounding, or dark scratches with light peaks next to them. They are in no way tactile, do not catch light, and only appear in the etch lol.

 

It's driving me nuts =/.

 

By the way, my etching process is very simple. I clean the blade, dip it in the ferric chloride solution for roughly 5 seconds, pull it out, neutralize with windex, then use the windex on the blade as a fluid base for Barkeeper's Friend...which is my free abrasive lol. I scrub the blade with my thumb/fingers until all traces of the oxides are gone...then clean, dry, and etch the blade again. This seems a very effective method for getting a very visible hamon, as you can see in the pictures above, and in this picture I took today:

 

DSCF3001.jpg

 

Please ignore the fact that the blade is obviously not in a stage of polish to require any etching lol. I just wanted to see what was to be seen. That was 4 cycles, and the blade is only at 120 grit on the edge, and still in file finish on the shinogi ji.

 

Anyhow...just thought I'd share...in an effort to find whatever the issue is with these lines!

 

Thanks guys =D

 

Cris

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I had thought that they came from carbides forming on vertical scratch marks. They appear only after the blade is hardened and etched and can be removed by normalizing. My correction is to make sure that all vertical marks have been removed and that all that is left runs lengthwise with the blade prior to heat treating.

 

When martensite starts to form it will seed along any sharp line or angle including 50 grit scratches. These can form stress risers and make a breaking point for the blade. Always horizontal prior to hardening.

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I had thought that they came from carbides forming on vertical scratch marks. They appear only after the blade is hardened and etched and can be removed by normalizing. My correction is to make sure that all vertical marks have been removed and that all that is left runs lengthwise with the blade prior to heat treating.

 

When martensite starts to form it will seed along any sharp line or angle including 50 grit scratches. These can form stress risers and make a breaking point for the blade. Always horizontal prior to hardening.

 

Aha!!

 

Thank you Sir!

 

Question answered =D.

 

Cris

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Chris,

 

This happens quite often. It can be very difficult to "read the scratches" during foundation polish. Often they will not show up until one or two stones later when everything is clarified. That is one of the many reasons that polishing can be so frustrating. It is often necessary to take one step forward / two steps back to get it really clean and clear.

 

I learned early on that there will always be these "hardened" scratches that are latent from the final rough shaping just before hardening. Especially if you use your grinder and create any scratches in the rougher grits perpendicular to the length of the blade. Then, if you are working traditionally, with your coarsest grit stone or paper you generally begin, again, perpendicularly to the blade. This sometimes hides the progress of the polishing and whether these hardened scratches have been removed, yet, or not.

 

Here are some things you can do to avoid and/or deal with these to make the polishing process a bit less frustrating:

 

*Draw-file your blade to final shape with a medium-course file before hardening it. This give a good surface for the clay to adhere, reduces those vertical scratches, and gives a very even surface to start with. I personally don't know how anyone can have the control necessary to do Japanese-style blades without draw-filing. I am just not a magician with the grinder, though...

*After hardening, use the finest grit on your belt-grinder that you can efficiently remove material to break down the edge and finalize the geometries. Use at least one step finer grit belt to finish the grind vertically (longitudinally--the length of the blade). Don't push the blade excessively into the belt. This will also cause excessively-deep scratches. Let the belt do the work, and go slow and easy--your geometries should be set with the rougher belt--now it is just scratch removal.

*When you do begin with your course stones or papers, make sure to address the blade and make sure it has had adequate treatment with each stone/paper before moving to the next grit. Keep the papers fresh, so as not to let them load up with hardened steel that will scratch the blade (this is why I use water-stones). I use water treated with baking soda through the entire process. Juggling oiled razor blades does not appeal to me.

*Before moving to the next grit, take a piece of 1000g wet/dry and buff the blade horizontally. You likely won't have to do this past 1000g, BTW--everything is generally apparent, by then. This will generally reveal any scratches missed on the current grit, and allow you to better assess the blade and "read" the scratches so you know if it is time to proceed or continue working with the current grit.

*If you are looking for a scratch-free surface after the etch, you will likely have to use loose abrasives before and after the etch to finish out those minuscule scratches left by 2500g. I have a variety of diamond films, loose abrasives, and lapping papers. Each thing creates a different effect on the final look. Just be sure you never burnish and are consistently opening the surface. Otherwise you lose some of the effectiveness of developing the hamon with the etch. A well-matched jizuya may help remove the very last scratches AND bring up some activities in the ji and ha of a monosteel blade, but will not really whiten the ha. You can try all day to match hazuya to monosteel. However, IMHO, it will never look as good ON MONOSTEEL as the etch. Hazuya has always left monosteel hazy and somewhat scratchy, to me. The reason it works so well on tamahagane is because the steel is so much SOFTER than monosteel. Maybe you have a source of super fine hazuya--but I have never found any that will work for monosteel.

 

I understand how you feel about wanting the blade perfect. That is just where you have set your standard. It just takes time and practice to achieve it efficiently. Another reason polishers get paid (deservedly) for their services. I can make three swords in the time it takes to polish ONE.

 

These are, of course, my own opinions and experiences. Please let me know if I was unclear on anything and need to clarify. I hope this is helpful to you and offensive to no one.

 

BTW, the polish looks very nice. I can see how you would like to get rid of those last scratches so it would be "perfect". As long as the customer is happy and reasonably got what he paid for it, I would consider this a learning experience and move on with new knowledge how to improve the next one.

 

Sincerely,

 

Shannon

Edited by J.S. Hill
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I always love reading your posts Shannon =D. You're a tad bit more traditional minded than I...BUT, I always pick up a hundred useful gems that I can integrate right into my own process. This post is no exception lol. I particularly like the cross buffing with 1000 grit between grits. Used 600 or 800 grit would likely do the same at lower grits...and will really help me get more use out of old paper too.

 

I agree completely on draw filing with Japanese blades btw...with the short little EDC blades like in the original post, there's too many subtle geometry changes over too small an area to really utilize a draw file. That 1" belt was really a godsend in that aspect. When using it I'll just have to remember to hand sand 120grit horizontal before heat treating.

 

Also, thank you for the compliment on the polish on that blade. I used the same process I outlined above, with the etchant being 4:1 ferric chloride, windex for the neutralizer, and Barkeeper's Friend as my abrasive cleaner. It's really just a trial and error thing to be honest. I think next time around I'll try vinegar rather than dilute ferric chloride...just to see if the effect is different. The ferric chloride just works well, and quickly...and on these little knives where the entire thing is $150...taking four + hours out to do 30 vinegar etches, versus half an hour for 3 or 4 ferric etches which still gives pleasant (at the minimum) results...just doesn't make sense lol.

 

Cris

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Chris,

 

That's because my work, up until now, has been more focused on the traditional side of things...

 

I am glad you appreciate my posts and understand them. I tend to get too technical and a bit too "inner monologue". I wonder if anyone gets them, sometimes. Anyone that has experience usually does, but I try to make them understandable for everyone....

 

I think worn 600-880g paper would be excellent recycling. Good idea.

 

I don't have a 1" belt. I draw-file everything....maybe habit? Even little kogatana. I have gotten really fast and really accurate. I completely understand about the economy of time on these little EDCs. Your idea to do a 120 grit longitudinal finish pre-heat treat should work fine.

 

Keep the vinegar for the art-polishes. Ferric DOES work fast and efficiently. For an EDC, you are better off to do a really harsh etch for a short period, with a good clean-up between. Makes for a more durable finish polish that will last longer. And is more commiserate with the time you spend vs. the amount you make off these very nice little knives. Three to four ferric cycles vs. countless with vinegar or otherwise.

 

BTW, vinegar is okay for art polishes, but I prefer augmented lemon-juice. The various etching agents all do something a little different. And you are right--each polish, each blade is JUST trial and error. You just keep going until you reach the results you want or decide is appropriate for the compensation.

 

Sincerely,

 

Shannon

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Keep the vinegar for the art-polishes. Ferric DOES work fast and efficiently. For an EDC, you are better off to do a really harsh etch for a short period, with a good clean-up between. Makes for a more durable finish polish that will last longer. And is more commiserate with the time you spend vs. the amount you make off these very nice little knives. Three to four ferric cycles vs. countless with vinegar or otherwise.

 

BTW, vinegar is okay for art polishes, but I prefer augmented lemon-juice. The various etching agents all do something a little different. And you are right--each polish, each blade is JUST trial and error. You just keep going until you reach the results you want or decide is appropriate for the compensation.

 

Sincerely,

 

Shannon

 

Anybody use the 10% or 20% vinegear available at organic garden shops?

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Anybody use the 10% or 20% vinegear available at organic garden shops?

 

I didn't know there was 10-20% vinegar available lol. I had been freezing mine out to increase the intensity!

 

Cris

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I didn't know there was 10-20% vinegar available lol.

 

Same here. That's interesting.

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On etching acids...I'll add that there is no doubt that ferric can etch a blade quickly but I have found that different acids bring up different activities differently. On the W1 blades Randal Graham used to make you would ruin the appearance by using ferric...it would eat out some of the more beautiful aspects and leave some of the coolest stuff unseen.

 

On etching, there is no "one size fits all" and I have found even on blades only finished to 220 grit (blades to be used hard or as EDC)and etched more cool stuff comes up with weaker acids than comes out with a very strong etch. Of course, everyone has a vision and if ferric gives you that "look" then you should by all means use ferric.

 

I finally settled on a dilute mixture of acetic, phosphoric, and citric acids in roughly equal proportions and heated to near boiling. The acid is cut with dish soap to increase its wetting ability and reduced in strength with distilled water.

 

On the lines issue I think Don has hit it right on the head - I learned a long time ago to harden after a decent finish was put on the blade with all the scratches going the long way. I finished to 220 grit before hardening as a general practice.

 

Brian

Edited by Brian Vanspeybroeck

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Brian,

 

AGREED! The different agents will draw out different effects. I have seen the nioguchi withered away by ferric way too many times. You lose all subtlety w/ ferric, and often acetic (vinegar). I, too, use a combination of acetic and citric acids and each alone for different effects. I'll have to try the phosphoric. And I agree that more etches w/ weaker acids give more detailed hamon / show more effects. I think, too, that a harsh etch w/ ferric usually gives a more durable finish that lasts longer on a lower grit finish for such things as cutting / training blades and EDCs.

 

Sincerely,

 

Shannon

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I agree with you guys completely. Sometimes if I etch for a few seconds too long, I get these crazy wavy lines that are literally etched into the blade about the habuchi. Even if I repolish the blade...it takes a substantial amount of polishing to remove these 'scratches' lol. It's a wierd effect.

 

I'll be honest...with my first tanto, I spent HOURS obsessing over getting a good, natural looking polish and etch. All I could get was a mirror finish with an admittedly cool silver/white double habuchi. The entire ha was literally mirrored though:

 

DSCF7869-1.jpg

 

DSCF7862-1.jpg

 

The most natural hamon I've been able to acheive has been with very quick dilute ferric chloride etches, and using only free abrasives to remove the oxides. I'm 100% sure this is simply due to my lack of experience, and lack of time to 'jiggle the handle'. Eventually I'll be able to take some time experimenting with various acids for the best finish...probably on my sword pictured above. For now though, the durability and appearance of the process I'm using now works, is relatively quickly achieved, and still manages to show quite a bit of activity.

 

It'll be cool when I can get into the other forms of etching though =D.

 

Cris

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I think we are all mostly on the same page. The only additional point I'd like to make is that different steels need different etches to bring up the possibilities. W1 that has been differentially heat treated using clay will give the best view of the various ctrystailine structures using a different final finish/etch than the same steel that has been soaked at a very low austenitizing temperature and then quenched and letting the steel harden only in the areas where it is thin enough to harden...making a hamon without clay. Same steel - different type of hardening routine with different types of structure present in the hard areas. So, they will need to be etched and final finished differently to get the most bang for the buck. This is very subjective and can require years of experimenting to get what we want.

 

I use 5160 and some O1 yet I still want to see as much contrast and "goodies" as I possibly can in the finished blade. To treat it like clay hardened 1050 is silly - it will not work.

 

So, my point is to become open to "jiggling the handle" and maybe doing the etch a couple of times with different acids over higher/lower grit finishes to maximize the results. I have found that my etch over a 400 grit final finish gives a subtle but different effect (on the same blade) than doing the same etch over a 2000 grit final finish. Both are nice but they are different and can be appreciated almost as two completely different blades.

 

I am always cautious of recipes with etching routines. The steel type and alloy, the heat treat, the activities present, and the final finish before the etch (as well as other things/factors) can drastically affect the outcome.

 

Brian

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Well I am not sure anything else can be said on this matter. I hope who ever reads this can apply what they have learned.

 

 

Oh one more thing I found that if you warm the acid solution even a little, will affect the blade in different ways the warmer the solution the quicker the etch. I found out the hard way with Lemon juice heated. It pockmarked the blade so bad that I had to scrap the blade.

 

As I have experimentd with Ferric, Vinegar and lemon Juice. And I have found that Vinegar when heated, stinks but has a very profound affect on the habuchi, and by that I mean making it whiter or so it seemed to me.

 

Well I just wanted to toss that in since I did not see it anywhere else in the thread.

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