While Sharpening and Mirror Polishing, Why Not Burnish In Some PTFE?

NRA

NRA

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PTFE is the worlds most slick substance invented in a lab (last time I checked). Guinness says it is the only thing a gecko cannot climb.

I have some of this marvelous stuff that I a going to try sharpening a knife with as fluid on my stones. My only reservation is this. What might it do to the sharpening media?

http://www.amazon.com/gp/product/B00BCVXUR6/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

61g9dKyAYPL._SL1500_.jpg
 
Everything I've ever heard or read about PTFE suggests it coats and clings tenaciously to whatever surface it's applied to, with the end-goal being a reduction of friction-induced wear. I can't envision anything good coming of that in a sharpening scenario, where abrasion (friction) is supposed to do the work of sharpening. It seems to me, at best, sharpening might 'feel' smoother in using it, but I'd expect a loss of grinding efficiency otherwise. The oils or other fluids normally used in 'lubricating' a stone are intended to float swarf off the surface, to keep it from clogging the stone, but not eliminate friction. They're also generally supposed to be relatively easy to clean off the stone, when it's necessary. A product designed to coat & cling to a surface may not be very simple to get rid of. I just don't see much to be gained in doing this. And if it does cling stubbornly to whatever surface it's applied to, you may never get it out of your stone once it's there.

If your stone is expendable, feel free to give it a try. But I don't think I would. When it comes to lubricating a sharpening stone, 'keep it simple' is my guide. I think this may be over-complicating the process, maybe to it's detriment.


David
 
The purpose of putting oil on a stone is to lift up the swarf (metal particles and stone,) float them away, and keep the stone from getting glazed over. It's not really for lubricating the stone. Water with a bit of dishwashing liquid can work just as well unless the stone's been oiled before.
The silicone carbide stones that John Juranitch of RazorEdge systems sell are recommended to be used absolutely dry. I've worn out two sets of his stones and never had them get glazed. The flattening process removes the top surface preventing that from happening.

The lubricant that you have will work well for moving things; pivots, hinges, etc., anything that isn't under pressure or heat. I wouldn't recommend it for sharpening stones.


Stitchawl
 
If your going to try it may I suggest doing it on a cheap expendable stone or using some sandpaper to test it out on. No point in ruining a perfectly good stone.

Though the flamable and harmful vapor part is what worries me more. I am not worried about it spontaneously catching fire, but you are grinding a piece of metal against a hard surface which will cause heat. How much so I don't know but it's bound to be more than we feel in the blade and stone at a very small area we don't notice. I am more worried about that heat combined with that lubricant heated up may offset some not so fun gas vapors. And one of the things I've learned in hazmat was just because you think the smell went away, it doesn't mean it did. More than likely it just overwhelmed your senses (ever see someone let a fart rip and stay in the room and they think it passed but the new guy walks in and says it stinks in there, same story). Even if the vapors don't affect you as far as you can tell, there is the bigger question of what will it do to your over time.
 
I would note the "harmful or fatal if swallowed" on the warning.

I bet it would be interesting to try with pivots and gun mrchanisms.
 
If you really want to try it, maybe use it as a final stropping step. Load a balsa strop (available at the local craft store (Michaels, hobby lobby, etc) and see if it makes any difference. My expectation is that it can't hurt, but will not be measurably better. (It may be better, but you would be hard pressed to prove it.) IMO, the hazardous properties are way over rated. I know I'd grab a hot french fry off a baking sheet, dunk it in ketchup, and think nothing of it, even if my hand's were covered in the stuff.
 
My thought are, what would this do for (or to) the blade? Would it make the blade stronger in regards to longevity of sharpness?

Would it increase the sharpening times?

I am going to soak a set of new stones, (edge pro size 180, 400, 800 & 1500 grit) and sharpen some new knives.

I will report the effects (if any) to this thread.
 
Teflon (PTFE) laps are used in the optics industry to create super-smooth surfaces, such as for optical flats.

"Teflon polishing is compared with pitch polishing as a method for achieving supersmooth and flat optical surfaces. Because a Teflon lap wears slowly, it will retain its surface shape to produce extremely flat optical surfaces, &#955;/100, consistently and reliably for extended periods of time, of the order of days. To compare the two methods, we polished 50-mm-diameter samples of various optical materials, using colloidal suspensions in water on both pitch and Teflon laps under the same polishing conditions. Flatness was maintained to better than &#955;/10, and roughness less than 10 Å rms was measured on all samples by two Talystep surface-profiling instruments, one in the United States and one in Australia, with excellent agreement between measurements made by the two instruments. It was possible to obtain flat and smooth surfaces (<4-Å rms roughness) on all materials (except for F4, flint glass), but only certain combinations of material, abrasive, and lap could be used to give the correct polishing conditions and surface chemistry."

Source:
https://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-31-10-1472


But I would not put PTFE on a sharpening stone... it might clog the surface, like wax on sandpaper. Lubricants are generally used to separate surfaces, and I think you don't want to separate the knife from the abrasive grains.
 
^^If I'm not mistaken, the teflon used in glass-polishing is as a very optically-smooth and wear-resistant coating, not as a polishing abrasive. Either that, or as a medium for holding abrasives used in polishing optical glass. Looking up hardness specs for teflon/PTFE, it seems it's usually hardness-rated on a scale for plastics or 'thermoplastics' (Rockwell 'R' scale or 'Shore' scale), not for steels (Rockwell C). Think of the warning about not using metal utensils in teflon-coated cookware, as the teflon might be damaged by them.

(quoted from DuPont's site: http://www2.dupont.com/Teflon_Industrial/en_US/products/product_by_name/teflon_af/apps.html )
"Optical Materials
The properties of Teflon® AF, including optical clarity, low refractive index, and exceptional UV stability and UV transmission capability, make it an ideal candidate for optical devices for medicine, military, and aerospace industry.

Teflon® AF amorphous fluoroplastics can function as a clear coating for optical devices requiring a low refractive index and yet perform in aggressive chemical environments over a wide range of use temperatures and light waves (UV-IR)-performance with clarity. Possible applications include lens covers for microwave, radar and optical devices; optical cladding; optoelectronic devices; UV cells and windows; passivation and protective coatings; and anti-reflective coatings for optical devices."
Click to expand...

David
 
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In the article I linked, the Teflon is not used as an abrasive. It is used as a lap, where you embed loose abrasive in the lap. Stropping is a form of lapping, I think, where the lap is usually leather or balsa wood. In glass polishing, the lap is usually made of pitch. Interestingly, teflon can also be used as a lap in glass polishing.

https://en.wikipedia.org/wiki/Lapping

There are a couple forms of teflon, but they are all really soft (like PTFE sealing tape, teflon pads for computer mice, etc.).
 
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I am going to use two separate sets of grits, one treated with water, one treated with PTFE. First with the water, then the PTFE, sharpening on coarse to fine.

This will cut the steel with water, then burnish with the PTFE.
 
Lagrangian said:
In the article I linked to, the Teflon is not used as an abrasive. It is used as a lap, where you embed loose abrasive in the lap. Stropping is a form of lapping, I think, where the lap is usually leather or balsa wood. In glass polishing, the lap is usually made of pitch. Interestingly, teflon can also be used as a lap in glass polishing.

https://en.wikipedia.org/wiki/Lapping

There are a couple forms of teflon, but they are all really soft (like PTFE sealing tape, teflon pads for computer mice, etc.).
Click to expand...

Yep, I'm reading that too (teflon used to hold polishing abrasives). Updated my previous post accordingly.

I'm still learning new stuff about teflon/PTFE that I hadn't known before. Interesting topic. That said, still doesn't sound too good to be coating a sharpening stone in it. :)


David
 
How best to get PTFE in the pores of the steel, of a knife blade?

Seems the best plan of attack, in my mind, would be to apply the PTFE and burnish it in at all stages of sharpening, not just the final stages.

If let to sit, the PTFE falls out of suspension, and lands in the bottom of the bottle. I have purchased two bottles, and I am going to skim off the top layer of the two unshaken bottles, and combine what is left, to get a stronger concentration of PTFE.
 
Knowledge is never off topic. Thanks for sharing, always keen on learning new things.
 
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