Blade coatings: what do they mean.practically?

topcatman said:

th coatings don't actually get on the cutting edge. if the coatings got on the sharpened cutting edge you wouldn't get much cutting done.

what they can do is make the appearance nicer, and make the blade easier to clean off between passes.

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The PTFE coating reduces force to cut, and it often extends to the cutting edge. Here is a quote from the original Fischbein patent, US3071856, filed 1959 and published in 1963.


The market agreed with Mr Fischbein. When Wilkinson-Sword introduced PTFE-coated stainless steel DE blades in the early 1960s, they took the market by storm and every blade maker was forced to follow with their own PTFE-coated stainless product. Eventually Gillette collected royalties on this patent from other blade-makers, despite being last to market with their own PTFE-coated stainless blades.

After this, blade-makers continued to extend the technology and improve their manufacturing processes. Many of these patent filings also mentioned reduction in FTC.

• US3224094: The coated blades were found to have the following appearance and were preferred by the shaving panel over the uncoated blades for the following reasons: The microscopic grooves in the edge of the blade were filled in with resin giving a smooth edge. The blades gave a smoother shave than an uncoated blade, i.e. there was less tendency for the blade to pull and the result was a much more comfortable and quicker shave compared to an uncoated blade. ...the polyethylene resin serves a twofold purpose; first, it serves to smooth out the edge of the blade by filling in the microscopic grooves and second, it serves as a binder for the discrete particles of polytetrafluoroethylene which, during the shaving operation, act as minute lubricating particles on which the blade can ride, permitting an extremely comfortable shave. The shaving panel results indicated a unanimous preference for blades coated in this manner over uncoated blades of the same type.
• US3518110: The remarkable increase in shaving effectiveness manifested by the blades of the present invention is characterized by a decrease in pull as compared to uncoated blades; that is, a decrease in the force required to cut the beard hairs, which becomes apparent in the noticeably increased ease of shaving.
• US3638308: ...the shaving properties of razor blades may be appreciably enhanced by adhering a solid polyether polymer to the cutting edge. The improvement is characterized by a decrease in the force required to shave, which manifests itself in decreased pull and markedly increases comfort and ease. The reduction in pull may persist during several successive shaves with the same cutting edge, but it generally does not persist indefinitely. When the blades of the present invention are tested under carefully controlled conditions off the face, they require substantially less force to cut water-softened hair than do similar blades without the integument. [...] Generally with most coating techniques the coating will actually extend around the ultimate edge.
• US5263256: The pain and irritation produced by shaving with uncoated blades are due to the excessive force required to draw the cutting edge of the blade through the unsoftened beard hairs, which force is transmitted to the nerves in the skin adjacent the hair follicles from which the beard hairs extend, and, as is well known, the irritation produced by excessive pulling of these hairs may continue for a considerable period of time after the pulling has ceased. Blade coatings were developed to solve these shortcomings.
• WO2010081118A1: The addition of PTFE (e.g., telomer) coating to the blade cutting edge dramatically reduces the cutting forces for beard hairs or other types of hair fibers. A reduced cutting force is desirable as it significantly improves shaving attributes including safety, closeness and comfort. Such known PTFE-coated blade edges are described in US Patent No. 3,071,856.

That last patent is quite recent: filed in 2009 and published in 2010, for Gillette. You might have noticed that it even cites the original Fischbein patent. Blade-makers continue to work on improved ways of applying PTFE-based coatings on blades, in the name of reduced FTC.

Coating a blade, with, say, Platinum, would add an additional (expensive) material to the blade, and also another process in producing the blade. And yet, say, an Astra Super Platinum blade costs the same, or even less, at retail, than an Astra Stainless Steel. And SuperMax Platinum blades cost the same, or even less, than SuperMax Stainless Steel blades.

I don't think there's anything to it.

Take a look at http://badgerandblade.com/vb/showthread.php/386550-Scanning-Electron-Microscope-Blade-Edge-Images for good evidence that some blades have a platinum coating: look for "Pt" in the elemental analysis. However the words on the label do not necessarily match that analysis. Sometimes the label says platinum but the blades have none, and sometimes the label says nothing about platinum but the blades have some.

I conclude that blades have coatings, and these coatings affect the shave in various ways. But unless blade-makers improve their labeling, we might as well ignore what the wrapper says and focus on the shaves.

"There is only one blade, and many different wrappers."
- Confucius.

People are nto undersstanding the issue of friction in cutting. No matter how sharp the edge, the blade still has to be able to "slide" through the material it is cutting. Think of how they have to oil blades to get them to cut through thick wood. Or better yet for a simple example that everyone can understand, take the sharpest knife you own and try to cut some soft cheese with it. It just gets "stuck" in the cheese even though the edge is very capable of cutting into and through the soft cheese.

With that in mind it seems completely reasonable to me that coatings can make a blade "slide" more easily through a whisker after a sharp edge has cut it. We all know the experience of "drag". But it might well be a factor of BOTH the edge and how well the blade "slides through" the whisker.

mblakele said:

The PTFE coating reduces force to cut, and it often extends to the cutting edge. Here is a quote from the original Fischbein patent, US3071856, filed 1959 and published in 1963.

... by providing on the cutting edge of a safety razor blade a thin integument of a fluorocarbon which is adherent to the substrate, the blade exhibits a remarkable increase in shaving effectiveness. This improvement is characterized by a decrease in pull; that is, a decrease in the force required to cut the beard hairs, which manifests itself in markedly increased ease and smoothness of shaving...

...blades of the present invention when tested under carefully controlled conditions off the face require much less force to cut water-softened hair than do similar blades without the integument. This reduction in pull may persist during several successive shaves with the same blade putting edge, although it does not persist indefinitely.

The fluorocarbon integument or coating may extend over the entire wedge faces back from the ultimate edge or even farther, or it may cover only the portion of the final facet immediately adjacent to the ultimate edge. The precise thickness of the integument does not appear to be critical, a thin continuous adherent coating having a thickness of the order of an oriented monolayer of molecules having been found effective for the purpose of the present invention. The thickness of the integument need not be uniform throughout its extent.
​

The market agreed with Mr Fischbein. When Wilkinson-Sword introduced PTFE-coated stainless steel DE blades in the early 1960s, they took the market by storm and every blade maker was forced to follow with their own PTFE-coated stainless product. Eventually Gillette collected royalties on this patent from other blade-makers, despite being last to market with their own PTFE-coated stainless blades.

After this, blade-makers continued to extend the technology and improve their manufacturing processes. Many of these patent filings also mentioned reduction in FTC.

• US3224094: The coated blades were found to have the following appearance and were preferred by the shaving panel over the uncoated blades for the following reasons: The microscopic grooves in the edge of the blade were filled in with resin giving a smooth edge. The blades gave a smoother shave than an uncoated blade, i.e. there was less tendency for the blade to pull and the result was a much more comfortable and quicker shave compared to an uncoated blade. ...the polyethylene resin serves a twofold purpose; first, it serves to smooth out the edge of the blade by filling in the microscopic grooves and second, it serves as a binder for the discrete particles of polytetrafluoroethylene which, during the shaving operation, act as minute lubricating particles on which the blade can ride, permitting an extremely comfortable shave. The shaving panel results indicated a unanimous preference for blades coated in this manner over uncoated blades of the same type.
• US3518110: The remarkable increase in shaving effectiveness manifested by the blades of the present invention is characterized by a decrease in pull as compared to uncoated blades; that is, a decrease in the force required to cut the beard hairs, which becomes apparent in the noticeably increased ease of shaving.
• US3638308: ...the shaving properties of razor blades may be appreciably enhanced by adhering a solid polyether polymer to the cutting edge. The improvement is characterized by a decrease in the force required to shave, which manifests itself in decreased pull and markedly increases comfort and ease. The reduction in pull may persist during several successive shaves with the same cutting edge, but it generally does not persist indefinitely. When the blades of the present invention are tested under carefully controlled conditions off the face, they require substantially less force to cut water-softened hair than do similar blades without the integument. [...] Generally with most coating techniques the coating will actually extend around the ultimate edge.
• US5263256: The pain and irritation produced by shaving with uncoated blades are due to the excessive force required to draw the cutting edge of the blade through the unsoftened beard hairs, which force is transmitted to the nerves in the skin adjacent the hair follicles from which the beard hairs extend, and, as is well known, the irritation produced by excessive pulling of these hairs may continue for a considerable period of time after the pulling has ceased. Blade coatings were developed to solve these shortcomings.
• WO2010081118A1: The addition of PTFE (e.g., telomer) coating to the blade cutting edge dramatically reduces the cutting forces for beard hairs or other types of hair fibers. A reduced cutting force is desirable as it significantly improves shaving attributes including safety, closeness and comfort. Such known PTFE-coated blade edges are described in US Patent No. 3,071,856.

That last patent is quite recent: filed in 2009 and published in 2010, for Gillette. You might have noticed that it even cites the original Fischbein patent. Blade-makers continue to work on improved ways of applying PTFE-based coatings on blades, in the name of reduced FTC.

Click to expand...

Thanks for the great information

mblakele said:

Take a look at http://badgerandblade.com/vb/showthread.php/386550-Scanning-Electron-Microscope-Blade-Edge-Images for good evidence that some blades have a platinum coating: look for "Pt" in the elemental analysis. However the words on the label do not necessarily match that analysis. Sometimes the label says platinum but the blades have none, and sometimes the label says nothing about platinum but the blades have some.

I conclude that blades have coatings, and these coatings affect the shave in various ways. But unless blade-makers improve their labeling, we might as well ignore what the wrapper says and focus on the shaves.

Click to expand...

It looks like the Gillette Silver Blue has Platinum in or on it, but I haven't seen the PTFE listed. Does that mean it's coated in platinum, and not PTFE?

Penknight said:

It looks like the Gillette Silver Blue has Platinum in or on it, but I haven't seen the PTFE listed. Does that mean it's coated in platinum, and not PTFE?

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Platinum and then PTFE, I think. Take a look at this image done with my cheap little USB scope:



But why not in the SEM analysis? This is what the gent who did the SEM work said about that:

Evil4blue said:

As for detecting the fluorine in PTFE coatings, there should be a peak at about 0.7 keV, but iron has a secondary peak in the same location and it completely overshadows the F peak. EDS wouldn't be the correct test for detecting a teflon coating.

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BSAGuy said:

Nothing, really. Marketing hype. What difference could a coating possibly make on an item that you are going to use 4-5 times and discard?

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imfallen_angel said:

As far as I know the coatings is for two things

1-rust prevention
2-helps prevent snagging and buildup

From reading about older blades that didn't have these coatings, the blades would rust and lose their edge a lot faster.

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My experience with the coated and un-coated Treet carbon steel blades seems to bear out the longevity part of imfallen's statement (at least one additional shave from the coated version of a Treet carbon and visible rust on un-coated edges after a week or so of exposure to high humidity), however the un-coated blades are still quite acceptably smooth compared to many coated blades, so coating certainly isn't essential for a smooth shaving blade.

I'm not a chemist my any means and haven't understood most of what I have read.

I was thinking that PTFE was a type of teflon. This made sense since you want something with less friction. Am I wrong?

Then what property does Platinum bring as a coating?

awa54 said:

My experience with the coated and un-coated Treet carbon steel blades seems to bear out the longevity part of imfallen's statement (at least one additional shave from the coated version of a Treet carbon and visible rust on un-coated edges after a week or so of exposure to high humidity), however the un-coated blades are still quite acceptably smooth compared to many coated blades, so coating certainly isn't essential for a smooth shaving blade.

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That was more or less my experience with coated carbon steel, too — the Captain CS made by Lord. However carbon steel and stainless steel are very different beasts. I suspect that the grain structure of stainless steel creates more friction, so an anti-friction coating is essential. Anyway uncoated attempts at stainless steel blades all failed: for example the ca. 1929 Gillette Kroman blade, the Darwin cobalt steel, and the Silver Star. I have shaved with a Silver Star myself: sharp enough, but very uncomfortable. Then ca. 1962 the first coated stainless blades were an overnight success. The difference was the new PTFE coating.

imatabor said:

I'm not a chemist my any means and haven't understood most of what I have read.

I was thinking that PTFE was a type of teflon. This made sense since you want something with less friction. Am I wrong?

Then what property does Platinum bring as a coating?

Click to expand...

More or less, but Teflon is a registered trademark for a type of PTFE. PTFE is the generic term.

Platinum brings hardness and anti-corrosion, both of which improve blade longevity. Schick pioneered this area. In 1962 they filed US3203829 for applying Teflon or other PTFE coatings to a razor blade. Gillette had already patented that idea, but Schick figured out how to improve on the process, which involved baking a solution of PTFE onto the blade:


Put simply, you have to get the blades really hot to get the PTFE to stick. But when you get stainless steel really hot, it wants to corrode. Corrosion can only happen when oxygen is around, and it helped to use an oxygen-free environment. But it worked even better when they tried a reducing atmosphere: a mix of hydrogen and nitrogen, for example, with no oxygen. The patent appeared on Schick Super Krona blades in the 1960s. But I think the process was a little expensive and cumbersome. Anyway they kept looking for ways to improve on it.

In 1967 they filed for a new patent US3632494 on a new coating method using chromium. The idea here was to form and sharpen the stainless steel blade as usual, then use RF sputtering to coat it with an even harder and more corrosion-resistant alloy. This was used for Schick Platinum Plus blades, and the method applied equally well to chromium, platinum, or a mixture. Then they would apply a PTFE coating over that. The exact technique for applying the PTFE no longer mattered as much, because of the hardness coating underneath.

Other blade makers followed, and modern DE blades still follow the same basic design. Gillette also uses the same basic idea for their cartridge blades: stainless steel, then a hardness coating, then an anti-friction coating. But they use more exotic materials like DLC for the hardness coating, and a derivative of PTFE that they call "telomer". Some of these materials do not stick together easily, so they use adhesion layers in between — like primer for paint.