YAST - Yet Another Sharpening Thread - How sharp are scalpels?

[David Laaneorg]

Just wondering, how sharp are scalpels? Nothing fancy like the obsidian blades used for eye surgeries (studies have confirmed that these blades can get down to single molecule edges), just the garden variety disposable scalpels they use in emergency rooms. Are they simply autoclaved X-Acto blades? How much are X-Acto blades sharpened?

The thing is, I've heard Black Arkansas stones called surgical stones, and from what I've found most of them rate around 5000 grit. So when I pull out my 8000 grit stone, do I run my shop sharper than most surgical rooms?

Just wondering.

[Mike Henderson]

I've bought scalpels to cut veneer. In my opinion they're not that sharp. However, they seem to work well for doctors to cut flesh.

Mike

[Keith Outten]

David,

I friend of mine gave me several packages of blades made by Bard-Parker Company Inc from Rutherford NJ. They are sterile carbon steel rib-back blades and they are much sharper than any X-acto knife blade I have ever used.

I'm not sure that these blades would be better for carving wood or any hard material than an X-acto knife as the edge may roll over they are so sharp but for soft materials they cut clean with almost zero effort. When I get the chance I will try them with a piece of wood.
.
.

[Walter Plummer]

On the tv show How It`s Made they showed the blades punched out then both edges ground at once under high pressure coolant. No honing or stropping shown or mentioned. The blades were then dried ,packaged and then run through radiation to sterilize everything. It was on tv so it must true.;)

[Johnny Kleso]

When I lived in NJ I did work for Becton Dickinson owner of Bard Parker and had a few disposable bladed BP scalples and they are nothing special..

They are made to make a few cuts and be thrown away..
Maybe a old time scalple would be what you would want..

[David Laaneorg]

I should rephrase slightly, I'm not interested in using scalpels, I'm just wondering if my chisels and plane blades are sharper than scalpels. I'm pretty sure that anything above 8000 grit will be sharper than a scalpel, I was just wondering if your average chisel sharpened to 8000 was sharper. Anyone know?

[Jonathan McCullough]

I used to be in medical supply, and we supplied scalpels and scalpel blades to the hospital. The blades we had came in about a total of ten styles/sizes. Some came with plastic handles, some came only as blades. The former were for regular use, the latter were for surgeons who had special handles, as I recall. They can be particularly particular. They were all disposable. I don't know what kind of steel they were, but they were perfect for cutting soft tissue. Theoretically, I don't see why someone couldn't use a scalpel blade for whittling, though they are a bit thin, and any high-carbon steel could be sharpened to progressively higher grits to a point where you could shave with them, make an incision, or carve a figurehead out of wood. I've been on an oil stone exploration lately, and the explanation I've gotten for "surgical" on some of the oil stones is that they are used by people who process surgical equipment for dentists and orthopedic surgeons, etc. As I recall, they have special surgical gouges and chisels for digging around in abscesses, knee and hip replacements, and other fun stuff. I've just recently gotten one of those stones BTW. The grain appears to be very uniform, and the stone came flat, but I haven't had a chance to use it yet. The best deal I found was at a chef's knife place, Chef Knives to Go. $70 for an 8 x 3 x 1 Hall's Pro Edge Surgical Black, free shipping, FWIW. I'm planning on following it with a strop, which is supposed to be approximately 16,000 grit.

[Peter Cobb]

They are far too thin and brittle. (Or if you must, be VERY careful).
Another point is as resterilizing is unacceptable for blades price constraints limit the quality of the steel so "surgical steel" can actually suck big time. For some surgeries I'll use upto 15 scalpels (blades actually as the metal handles are resterilizable), some of them give up after one incision (TRULY "one-use-only" disposable :D).
Acceptable edge life is probably about 3 minutes in hand surgery... It would be rather off to get up to hone them.
On the sharpness issue, yep you can get your tools as sharp as scalpels if your technique is good... most of us know first hand (usually left hand :p) how easy it is to cut yourself. Scalpels are quite close to a new craft knife blade.
On the plastic handle disposable ones: the balance is crappy and they are more expensive than the loose blades.
Take care and enjoy good quality steel in your tools!
Cheers,
Peter

[Caspar Hauser]

They are far too thin and brittle. (Or if you must, be VERY careful).
Another point is as resterilizing is unacceptable for blades price constraints limit the quality of the steel so "surgical steel" can actually suck big time. For some surgeries I'll use upto 15 scalpels (blades actually as the metal handles are resterilizable), some of them give up after one incision (TRULY "one-use-only" disposable :D).
Acceptable edge life is probably about 3 minutes in hand surgery... It would be rather off to get up to hone them.
On the sharpness issue, yep you can get your tools as sharp as scalpels if your technique is good... most of us know first hand (usually left hand :p) how easy it is to cut yourself. Scalpels are quite close to a new craft knife blade.
On the plastic handle disposable ones: the balance is crappy and they are more expensive than the loose blades.
Take care and enjoy good quality steel in your tools!
Cheers,
Peter

Y'know, maybe you should have a word with Rob Lee.

http://www.canica.com/standardscalpel.asp

Now I know that some of you have electron microscopes next to your stones, does anyone have one of these?

http://www.catra.org/pages/products/kniveslevel1/st.htm

I have no idea how many units of what describe actual sharpness, but the machines manufacturers report;

'- Typical sharpness levels :- Razor blade 0.3 to 0.4N, Scalpel blade 0.4 to 0.6N, Utility razor blade 1.0 to 1.4N, kitchen knife ( new) 1.8 to 3 N, Hunting knife 1.9 to 3.5, Well worn blade 6.0 to 11.0'.

So it would seem that a modern disposable scalpel blade isn't quite as sharp as a razor blade but is sharper than a utility knife blade. Where an 'Xacto' blade or indeed an historic scalpel fits in this scheme of things is at present a mystery.

I can however report that razor blades, modern scalpels, utility knives, chisels, lion trimmers etc will all slice you up a treat, scars to prove it etc.

Now, back to my wet brick...

[john brenton]

Your planes and chisels are way sharper and harder. Regular old pakistani (no offense, they are just the most common producer) scalpels won't even shave arm hair if you rake it across your skin, whereas a sharpened chisel or iron's edge should be keen enough to float it above the skin and catch and cut into the hair itself.



I should rephrase slightly, I'm not interested in using scalpels, I'm just wondering if my chisels and plane blades are sharper than scalpels. I'm pretty sure that anything above 8000 grit will be sharper than a scalpel, I was just wondering if your average chisel sharpened to 8000 was sharper. Anyone know?

[Mike Davis NC]

Back 30 years ago when I was cutting silk screen designs in lacquer film and later in rubylith film for photo screens I would routinely sharpen new X-acto blades as they were not sharp enough to cut the film without denting the backing. So, the factory edge can be improved and I know my chisels and planes are sharper than most razor blades. I can cut my arm hair without touching the skin.

Not being a surgeon I could not say much about a scalpel, so I take the word of those above.

[Charles Goodnight]

Its really the same question of how sharp are your chisels. The older scalpels were made with high quality steel, but not particularly sharpened. they have a sharp angle, then you sharpen a secondary bevel on them. They can be as sharp as you choose to make them. Most do suffer from being stainless steel, which doesn't hold an edge that well. Of course that is probably ok since they are designed to cut soft material (flesh) and stropped between each use.

Perhaps the most amazing blades you will see are microtome blades. These are machines designed for making shavings of mounted tissue for microscopic examination. My parents had such a blade lying around when I was a kid. It was for a long defunct microtome. The blade was about an inch thick at the base, and had a long about 20 degree taper to an edge with a microbevel. It was very sharp.

[Tony Shea]

Perhaps the most amazing blades you will see are microtome blades. These are machines designed for making shavings of mounted tissue for microscopic examination. My parents had such a blade lying around when I was a kid. It was for a long defunct microtome. The blade was about an inch thick at the base, and had a long about 20 degree taper to an edge with a microbevel. It was very sharp.


Very similar to my histologist friend that works at the Jackson Lab. His job as a histologist is to slice very thin slices (microns thick) of mice flesh, organs, etc for examination under a microscope. This blade is fixed inside a machine similar to that of a larger deli meat slicer. Im really not sure what this blade is or how it works exactly but when your cutting micron thin slices that have to remain very flat and whole, then your blade is seriously sharp.

[David Laaneorg]

I have no idea how many units of what describe actual sharpness, but the machines manufacturers report;

'- Typical sharpness levels :- Razor blade 0.3 to 0.4N, Scalpel blade 0.4 to 0.6N, Utility razor blade 1.0 to 1.4N, kitchen knife ( new) 1.8 to 3 N, Hunting knife 1.9 to 3.5, Well worn blade 6.0 to 11.0'.

I took a look at the description of the machine, and I think part of the problem with the design is that it does not take into account sharpening angle. You can have a very sharp edge, but that edge may be at 90 degrees, so by their testing methods, it would seem dull because they were pressing the edge into some kind of silicone rubber which will deform before being cut. Something slim like a razorblade will cut sooner, even though it may be duller, simply because the angle of the edge is smaller.

From what I understand, true sharpness is the fine-ness of the edge, that is to say how pointy is the aris. Again, as I eluded in the origional post, obsidian knife edges have been measured at 1 angstrom, which is 0.1nm, or roughly 1/250 millionth of an inch. An iron atom is around 1.5 angstroms, so it is physically impossible for an iron tool to be as sharp as an obsidian flake. But this is getting pointless already. Or is it getting a little too pointed? :p

Anyhow, again, I'm not interested in using surgical tools in the shop. I was just wanting to compare relative sharpness out of sheer curiosity.

[Gary Radice]

Very similar to my histologist friend that works at the Jackson Lab. His job as a histologist is to slice very thin slices (microns thick) of mice flesh, organs, etc for examination under a microscope. This blade is fixed inside a machine similar to that of a larger deli meat slicer. Im really not sure what this blade is or how it works exactly but when your cutting micron thin slices that have to remain very flat and whole, then your blade is seriously sharp.

I do this in my day job (sometimes). The machine does look like a deli meat slicer: the blade is held fixed and the tissue is moved over it. We use both disposable blades that are more or less about as sharp as disposable razor blades, or we use solid blades that we resharpen on glass plates with a carborundum slurry. Both of these I'd say are as sharp as the sharpest chisels I'd use for woodworking but the dispo blades are thinner and less durable. Both are MUCH sharper than scalpels.

In sectioning for microscopy the tissue is usually cut about 6-10 µm thin. That's about 0.0004 inches. Animal tissues can't be cut that thin unless they are first embedded in something harder, like wax or plastic.

If you embed them in plastic then you can cut them at 0.5 µm to 2 µm, but then you need glass or diamond knives. Steel knives can't be sharpened fine enough to do that.