# Steel is like cheese (troubleshooting deburring)



## captaincaed (Jan 31, 2020)

This reflects my current understanding, not to be interpreted as gospel.

When I envision sharpening, I want that hard, clean apex with no trace of a burr. My sharpening improved by miles when I focused on burr removal, and found it different for different steels. I like to have* mental models *to help envision the process. Without that clear mental picture, I get varied results. When you have to assess the edge, it helps to know what you're looking for. This is just one step of that process.

*Steels *are *cheese*. Some are *harder (friable)*, some are *softer (ductile)*. People complain about deburring "soft stainless." But why?










*Ductility* is the ability to pull a material out into a wire. We learned in chemistry that metals are *ductile*. When you rub a knife edge on a hard surface, you are both abrading and drawing a wire at the same time. When the steel is *hard* it is more *friable*, or easily crumbled. So the treatment of the steel balances these two properties. White 1 steel at 64 HRC will draw enough burr to detect, but easily deburr because it's more friable. A softer steel , like brie, will "smear" out so it's harder to detect where the "root" of the edge is, making sharpening challenging. (I'm looking at you, Buck Knives)

Can you imagine shaving brie like this? You'd never do it. But you can shave parmesan. Same basic ingredients, but different processing. You'd never try to draw wire out of hardened steel, and you'd never make ball-bearings out of mild steel. Horses for courses.






There must be other subtleties at play, but for basic deburring, I think ductility accounts for at least 80% of the association between sharpening and burr formation, and helps a beginner understand the process. I've never seen burrs and ductility mentioned together in this forum. Is this something talked about on other forums?

(Larrin, feel free to correct my terminology, I know steel isn't usually described as friable).

*Afterward:*
This reflects my current understanding, not to be interpreted as gospel.

I don't think the stainless bit is most important, I think it's the overall distribution of soft knives; more happen to be stainless due to marketing demands. High carbon steel tends to be for "those who give a a damn," so there is harder steel readily available. I don't think the stainless nature is as critical as softness and ductility. However, I do notice some differences in even hard (R2, AUS-8) steels compared to clean White 1.

I finished up the Carter sharpening video, were he has trouble getting a Buck knife sharp. Anyone else had this problem? I have _never_ gotten a Buck sharp. I don't think anyone ever has. He talked about the burr flopping over, and an advanced technique where you "pinch it off" with edge leading strokes. Sounds a lot like Kippington's Maneuver. We'll see when/if that video is uploaded.
(https://www.kitchenknifeforums.com/threads/kippington-deburring-video.44003/#post-648942)

Other edge assessment things I liked from the Carter video, as well as a couple from personal experience and help from some pros (I like that Carter showed different problems as he went to exhibit a real, live, troubleshooting process):

*Things that helped when I started sharpening*
This reflects my current understanding, not to be interpreted as gospel.

*Situation 1:



*
You have chips in the edge, so you can sharpen *most* of the edge, but be left with *tiny valleys *that haven't been sharpened out yet.
*Symptoms:*
You can shave hair and cut tomatoes, but *cutting paper is ragged*, as it catches on the tiny valleys. You still did a good job, but there is some old damage still at the edge.
*Solution:*
Live with it. Next time you sharpen, you will make those tiny valleys smaller, until one day they disappear. Or you can try to take them all out if you're concerned.

*Situation 2:*
[link to correct time - won't embed at correct time-point]
https://tinyurl.com/wayb6c6
You have sharpened your knife, stropped on a fine stone, deburred properly, and probably stropped on leather, or some other soft medium.
*Symptoms:*
You knife cuts paper cleanly and shaves hair, but *will not cut a tomato. *You have a good edge, but it's very smooth, since every edge is actually a veeeeery tiny radius (rounded). You may want to put some teeth/bite back in the edge to allow it to cut food.
https://knifesteelnerds.com/2018/08/27/what-is-edge-stability/
*Solution:*
Strop on your fine stone 5-10 times, or until you're happy. Be sure it's a stone that isn't glazed over (or broken down in the case of Arkansas stones), since you want fresh abrasive at the surface to contact the apex of your knife's edge.
As an aside, I suspect woodworkers like Arkansas stones and strops precisely because you get a smoother, less toothy edge, and that shaves wood more cleanly, leaving a more polished surface texture behind. Again, they're adjusting their tools to suit their particular job at hand. Horses for courses.
[link to correct time - won't embed at correct time-point]
https://tinyurl.com/rvzvlwe
Watch how much force he uses - we'd never do that with knives, but look at the wood-shaving results about a minute later.

*Situation 3:*
You have sharpened most of your knife well on your coarse stone, but there are some places where you have *not fully created a new apex*.
*Symptoms:*
You can feel a *burr *along most of the edge, but it's *missing in some little spots*. Often the heel or tip. Sometimes on the belly since that's a common spot for abuse.
*Solution:*
Spend a little extra time on that small section, until you are *sure* you have a *burr*.

*Situation 4:*
You have created a burr properly along the entire edge, but the belly (curve) of the knife hasn't been deburred properly, because that burr is *larger *than on the flat heel of the knife.
*Symptoms:*
Your knife cuts paper at the heel, but *struggles to cut cleanly at the belly*. It snags and catches on the fibers, cut after cut.
*Solution:*
You've likely used equal downward weight with your hand on all parts of the knife as you sharpen on the stone. *Reduce downward pressure* *slightly as you sharpen the* *belly*. When you sharpen the belly, equal weight down from your hand contacts a smaller surface area than when you're sharpening the long, flat heel. This in turn creates a larger burr *because metal is ductile*. Greater pressure = larger burr. This burr will take longer to abrade on your finishing stone, and may in fact be too large to remove properly if your steel is a bit soft. (Pressure = Force/Area; if force is equal, small area -> large pressure)
Also try this JKI sharpening video. I got an extra little extra tip on making it work well:
"Move your arm back and forth like a pendulum. The wrist, elbow and shoulder stay in the same plane. Your wrist twists slightly to allow the belly to roll and contact the stone along the entire curvature. Think of it like a coin coming to rest after spinning - it's the same motion for that area of curvature."


*Situation 5:



*
You have sharpened the entire blade and have an even burr, but you've made the burr large, and then moved on to a finishing stone too early.
*Symptoms:*
Your knife *does not pass any edge test well* after your finishing stone (paper, hair, finger test or tomato test), or it may cut briefly, but loses sharpness quickly after making one or two meals at home. There is still some floppy burr masking the hard apex.
*Solution:*
Completely deburr your edge after *every stone*, and try to raise a slightly smaller burr next time (incremental improvements). You *will *be able to cleanly draw-cut a page of phone-book paper after your 220 grit stone if you have deburred completely. It'll be a little coarse, but not ragged or rough, if that makes sense. It should cut heel to tip after 220 grit.

Image credits:
https://thehamandcheeseco.com/collections/parmigiano-reggiano
https://www.gourmetfoodworld.com/gourmet-food-world-big-softies-a-study-in-bloomy-rinds-12259
http://www.samcooks.com/grating-cheeses-grate-expectations/
https://www.researchgate.net/figure...hipped-edge-of-a-stone-product_fig3_269679554
https://scienceofsharp.com/2015/01/11/what-is-a-burr/ (don't get too hung up on their stuff, they're exacting, and have expensive toys that you don't have)


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## plluke (Jan 31, 2020)

Great summary!


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## RDalman (Jan 31, 2020)

Fantastic writeup


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## Michi (Jan 31, 2020)

captaincaed said:


> This reflects my current understanding, not to be interpreted as gospel.


Abso-bloody-lutely fantastic post! Thank you!


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## Carl Kotte (Jan 31, 2020)

This reflects the gospel, not any particular person’s understanding [emoji6]


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## vicv (Jan 31, 2020)

I like cheese. Oh and great write up too. 
Oh and Buck knives are easy to get razor sharp. Just need the right equipment. Norton Crystolon med/India fine stone. Deburr one or two strokes on leather impregnated with the slurry from the crystolon stone (After you've taken the stone as far as it will go ). Don't take it any further.


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## ian (Jan 31, 2020)

Awesome writeup.

Maybe one addition: on some people’s crappy knives that haven’t been sharpened in years, I’ll be able to create a small burr, but then the knife still won’t hold a reasonable edge.

Solution: really wail on it with a coarse stone until the fatigued steel is gone. Don’t keep trying to deburr perfectly until you do.


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## VICTOR J CREAZZI (Jan 31, 2020)

vicv said:


> Oh and Buck knives are easy to get razor sharp.


I'm a fan of Buck's 420HC steel too. I mostly sharpen edge leading once the grunt work is done.


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## vicv (Jan 31, 2020)

I can't argue with a man with such a great and winning name

Most of my pressure in sharpening is edge trailing as well as deburring. But at the end I do a couple swipes edge leading at roughly double the sharpening angle on these soft steels.


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## CoteRotie (Jan 31, 2020)

Nice! Thanks.


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## kayman67 (Jan 31, 2020)

True enough about what was said, but getting a Buck razor sharp is not a challenge. Next step is to understand abrasives. Get yourself a decent diamond plate, 4 or 600 is just fine and that's all you need. But again, this means everything else to be very well understood as well.


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## captaincaed (Jan 31, 2020)

Thanks for the feedback everyone. I felt like I had an aerial view of the issue for the first time last night, clearly went a little nuts...

I know there's a few newer sharpeners here who've been asking some questions. Hopefully this is a bit helpful


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## vicv (Jan 31, 2020)

This would definitely be very helpful to beginner sharpeners. It was well written and had many good key points


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## captaincaed (Jan 31, 2020)

I learned a bunch around these parts, hope this is worth paying forward.


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## RDalman (Jan 31, 2020)

I have been doing edge leading deburring for a long time but I recognize it requires quite consistent angles and ymmv, so results are what matters really as usual. This writeup should be extremely helpful for many imo.


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## captaincaed (Jan 31, 2020)

*Edit-addition*
(too long for original post)
*
Situation 6:*
You've sharpened and debburred properly, and finished your knife, however your edge does not feel very good after the final deburring.
*Symptoms:*
Your final edge, before deburring, felt toothy and great, but after deburring feels either too smooth or too rough. Something just doesn't feel quite right, and you feel a little disappointed with the results.
*Solution:*
Do 2-3 rounds of this: 5-10 edge trailing strokes (or edge-leading, if you can do it reliably) on your finishing stone with *steady angle and very light pressure*, then deburr again *lightly*. Repeat until you're happy. This is the "final coat of paint," and deburring with wood/cork/hard felt can leave the very edge less than ideal. It just takes a little "touch up paint" to get it looking good, and this last 1-2 minutes of work is *really worth it*.


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## captaincaed (Jan 31, 2020)

RDalman said:


> I have been doing edge leading deburring for a long time but I recognize it requires quite consistent angles and ymmv, so results are what matters really as usual. This writeup should be extremely helpful for many imo.


Thank you kindly, Robin. 
I added edge-leading finishing recently as well, thanks to Kippington. I found my edges seem to be a bit more durable than before. I agree it's a great way to finish, and I think I'm getting even better results. When I was learning, edge trailing and deburring was what got me "over the hump" / "turned on the light" from dull to sharp, and helped build my confidence


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## SeattleBen (Jan 31, 2020)

This was fantastic. I also had a devil of a time with some buck knives and honestly don't care if I ever see one again.


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## Desert Rat (Feb 1, 2020)

Where can I find the video of Murray having trouble with a Buck? I know he has a bunch on youtube but I don't want to wade through hours of them. 
Never been a big Buck knife fan but I do have a 70's skinner that has served me well. A few minutes on a washita is all it takes to produce the toothy edge that I like on it.


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## McMan (Feb 1, 2020)

I like cheesecurds and I like this post.
Thanks @captaincaed, cool way of thinking about things


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## vicv (Feb 1, 2020)

It's funny I don't usually like blaming a knife or a stone for a sharpening failure but I do have one I can not get a good edge on. Opinel corbone 6cm. Should be the easiest thing on earth to get razor sharp. From what I can tell the steel wasn't hardened. Edge just rolls over while sharpening even with the lightest touch.


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## VICTOR J CREAZZI (Feb 1, 2020)

vicv said:


> It's funny I don't usually like blaming a knife or a stone for a sharpening failure but I do have one I can not get a good edge on. Opinel corbone 6cm. Should be the easiest thing on earth to get razor sharp. From what I can tell the steel wasn't hardened. Edge just rolls over while sharpening even with the lightest touch.


Probably never heat treated. Think about a high volume factory, someone picks up an un heat treated blank off of the floor and tosses it into the 'to be finish ground' bin. I can see that happening very easily. Either that or they didn't clear the nose on a batch.


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## vicv (Feb 1, 2020)

Ya I'd imagine. I can't even get a good edge on it with my paper wheels. I can get a Tina can lid to shave with them but not this opinel. Lol. Have got another opinel in stainless and the thing get razor sharp when you breath on it
It's what I was getting at on the buck knives. Even soft low carbon stainless can still be sharpened well unless the heat treat was botched as long as it's a martensitic steel. And Buck does their heat treat right. And I'm not a big Buck fan but they make a quality product


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## San_ (Feb 1, 2020)

Thanks guys ,more I read more I lean !!


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## captaincaed (Feb 1, 2020)

Desert Rat said:


> Where can I find the video of Murray having trouble with a Buck? I know he has a bunch on youtube but I don't want to wade through hours of them.
> Never been a big Buck knife fan but I do have a 70's skinner that has served me well. A few minutes on a washita is all it takes to produce the toothy edge that I like on it.


It’s in the video in the link from the first post. It’s a pretty long video, but it’s worth it if you break it into chunks.


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## Phip (Feb 2, 2020)

kayman67 said:


> True enough about what was said, but getting a Buck razor sharp is not a challenge.


Owned a couple of Bucks years ago. Not worth the effort. Sure, I can get them sharp, but why bother? They certainly won't stay that way for long. Chris Reeve, Spyderco and many others mean there's no reason to get Bucked.


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## kayman67 (Feb 2, 2020)

I guess the challenge is not to use it after? )


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## vitreous (Feb 2, 2020)

This is my favorite post on the forum. I speak cheese so much more fluently than metal.


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## gman (Feb 2, 2020)

Very good


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## captaincaed (Feb 15, 2020)

It's funny, I was hoping someone would contradict me, and this would turn into a debate. I'm surprised how quiet this was.


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## kayman67 (Feb 15, 2020)

I've tried not to write anything and take the subject on a different path. Mainly because it would have been more of a yin-yang situation that I'm aware of. Too much emphasis on this property alone will eventually give false results, like something would be impossible to sharpen and this would justify it completely. In real life, things get a bit more complex. That is why some people said already that they could sharpen a certain knife. But there's an array of knives/alloys "impossible" to sharpen, that people talk about. Since, more or less, the same routine is used, it might not always work as expected. And we would have to address the complementary side, that's actually not easy to do. Except some perspective from Cliff Stamp, I haven't found that much consideration about to what extent alloy and pressure work in correlation with abrasive type and density and bond strength / porosity (if stones are used).
These are why we, sometimes, get results that are so very different from each other, looking like complete opposite ends.


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## Rotem Shoshani (Apr 19, 2020)

captaincaed said:


> *Edit-addition*
> (too long for original post)
> 
> *Situation 6:*
> ...



Hi captain, really love the writeup and it really kinda hits a sensitive spot for me regarding sharpening, as it really seems to be the part that is hardest for me.

I've got that same feeling today, just received a Mazaki Santoku and while I can get my knives sharp, just from cutting newspaper I can already tell that this will be the peak of sharpness of that knife. No way I can get that edge back, the thing cuts like magic.

Can you get into details about that last paragraph regarding cork and the edge being less desirable..?

I'm guessing you suggest to try and avoid deburring using anything but the stones?

Appreciate the writeup, it is wonderful.


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## kayman67 (Apr 19, 2020)

"deburring with wood/cork/hard felt can leave the very edge less than ideal"

Looks like he says the opposite. Those are less than ideal. You know exactly what to do.


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## Rotem Shoshani (Apr 19, 2020)

****, lemme rephrase that in the original post.

Exactly what I meant kayman.


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## kayman67 (Apr 19, 2020)

Yeah, now makes sense. 

Well, I guess anything works, but it's not as straightforward as expected. Remember the 8-10k edges and the strops. Anything requires some technique adapted.


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## captaincaed (Apr 20, 2020)

Rotem Shoshani said:


> Hi captain, really love the writeup and it really kinda hits a sensitive spot for me regarding sharpening, as it really seems to be the part that is hardest for me.
> 
> I've got that same feeling today, just received a Mazaki Santoku and while I can get my knives sharp, just from cutting newspaper I can already tell that this will be the peak of sharpness of that knife. No way I can get that edge back, the thing cuts like magic.
> 
> ...


I am still learning on this one honestly. I just find that if I stopped after deburring, I was a little disappointed, but doing some light stropping strokes after seems to help. 
Jon's videos are still the standard as far as I'm concerned. He deburrs with the stone and sometimes the rough side of a sponge be careful you get the blue kind because that doesn’t have any abrasive the green kind does have abrasive and will spoil the edge you just made


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## Rotem Shoshani (Apr 21, 2020)

Funny enough, I just emailed Jon last night, he's been tremendously helping me lately.

During the course of our conversation, he indeed suggested the sponge and I've been lucky enough to find it.

However, I'm using a green scotchbrite fir ALL my dishes, unfortunately at that, also on all my knives, so yesterday I accidently left a freshly sharpened white #2 Masakage Yuki gyuto wet, to find it developed some rust spots. So what do I do? Scrub the **** out of it with that devil green scotchbrite (mind you, we use only the rough side and buy those in a long strip). I'm checking the edge, it's dead.

So I've promptly emailed him asking if it possible I have just found my edge killer? I'm literally going out of my mind how come my 64HRC Konosuke Sanjo can't keep its edge for more than a few days tops (Corona days has my visiting the kitchen often, the kids have basically turned to fridge goblins).

So, I'm wanting on his response. If that's my case, I'll just go ahead and shoot myself for several dozen hours wasted and buffling forever why my edges wouldn't last.

For what it's worth, I've usually got the burr off the stones most times, VG10 was a little harder for me. It's just lately I got really obsessed with retention, wire edge, micro burr and micro chipping, since I had to go to the stones way too often, for home use, so I felt.

If appreciate if you could chine in on this scotchbrite mystery I might have dealing with in the past five ****ING (!!!) years.

I've added a picture if it might help.


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## kayman67 (Apr 21, 2020)

Do you remember what I first told you about things that matter and how you should consider them? On what you cut, the way you cut and so on. Lots of things. At this level, everything has an impact you can feel. When you get into this stuff, it's the price you pay eventually or you can't really benefit from best possible or potential performance. 
For freshly developed rust spots, start with a cotton pad, cork and polishing paste.


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## captaincaed (Apr 21, 2020)

One maker told me "most damage to knives happens in the sink." With children in the kitchen, that's not _always_ true, but it's a common source of damage.
Often, cleaning with a little spray-bottle of isopropyl alcohol (IPA) works well, then wipe with a soft rag or paper towel. The IPA cleans most things off, then dries quickly to avoid rust. 
And yes, most Scotch-brite pads are going to kill the edge due to embedded abrasives. I learned about the blue ones from Jon, there are probably others around but I'm not sure.


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## M1k3 (Apr 21, 2020)

I'd only ever use the actual sponge part, not any plastic scrubby/scratchy side.


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## ian (Apr 21, 2020)

M1k3 said:


> I'd only ever use the actual sponge part, not any plastic scrubby/scratchy side.



Is that even going to do anything, though?


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## MartinJ (Apr 21, 2020)

If u use hot water, no need for scratching pads


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## ian (Apr 21, 2020)

?

Actually, I hear that if you use hot water, you don’t even need stones!


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## captaincaed (Apr 21, 2020)

I think we're mixing conversations about deburring and washing


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## MartinJ (Apr 21, 2020)

Probably, but still. 
If you use hot water, you don't even need a knife!


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## M1k3 (Apr 21, 2020)

ian said:


> Is that even going to do anything, though?



For deburring, yes. For cleaning, yes with the caveat of using hot water.


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## M1k3 (Apr 21, 2020)

MartinJ said:


> Probably, but still.
> If you use hot water, you don't even need a knife!



What can I use so I don't need hot water?


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## captaincaed (Apr 21, 2020)

M1k3 said:


> What can I use so I don't need hot water?


Cheese


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## ExistentialHero (Apr 21, 2020)

M1k3 said:


> What can I use so I don't need hot water?



If the water's going fast enough, the temperature really doesn't matter:


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## Kippington (Apr 21, 2020)

_*furiously taking notes*_
Hot cheese... at 60,000 PSI...


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## captaincaed (Apr 22, 2020)

Kippington said:


> _*furiously taking notes*_
> Hot cheese... at 60,000 PSI...


This got a real laugh


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## Carl Kotte (Apr 22, 2020)

This is starting to get complicated. But the discussion here is starting to help me realize what I did wrong when I used my bread knife as a toothbrush the other day. Now I think that what I should have done instead is to use a scotchbrite and warm water, then rinse with cheese. Right? Teeth are like steel after all!?


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## M1k3 (Apr 22, 2020)

Hmmm, what if the water is stationary and the knife is moving really fast?  

What are the effects of a fish hook grind with chevrons on this? For science, of course.


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## Rotem Shoshani (Apr 22, 2020)

ian said:


> Is that even going to do anything, though?


That's the reason I'm scrubbing so much with those damned scotchbrite, it gives a feeling of cleanliness


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