You all ruined my Worksharp!

[dkb45]

OK I just read that Flexcut gold is .6 microns and up a little. Now I am totally lost. I could have lost sight and didn't see the decimal point. Now I really need to know, because stropping is how I fill my spare time.

Figure I may as well edit to add in my green compound. I use Woodstock green (I believe it is CrOx) and read that it is rated at .5 microns.

 

[HeavyHanded]

OK I just read that Flexcut gold is .6 microns and up a little. Now I am totally lost. I could have lost sight and didn't see the decimal point. Now I really need to know, because stropping is how I fill my spare time.

Figure I may as well edit to add in my green compound. I use Woodstock green (I believe it is CrOx) and read that it is rated at .5 microns.

I'll scare up one of my pieces of Flexcut and take a closer look on Tues - have a high powered microscope at work. I break down some of the compound on a clean slide with mineral oil and see what shakes out. If it looks strange I repeat this a few times. Have gotten very consistent results in the past and was able to determine the average abrasive size of several compounds with reasonable accuracy.

I've already done this with the Formax microhoning compound and Ryobi white and black, as well as a handful of others, have never done this with Flexcut.

 

[dkb45]

I'll scare up one of my pieces of Flexcut and take a closer look on Tues - have a high powered microscope at work. I break down some of the compound on a clean slide with mineral oil and see what shakes out. If it looks strange I repeat this a few times. Have gotten very consistent results in the past and was able to determine the average abrasive size of several compounds with reasonable accuracy.

I've already done this with the Formax microhoning compound and Ryobi white and black, as well as a handful of others, have never done this with Flexcut.

Flexcut said somewhere that they use a few different grits in their gold compound for both quick cutting and polishing capability.

 

[HeavyHanded]

Flexcut said somewhere that they use a few different grits in their gold compound for both quick cutting and polishing capability.

Some of the manufacturers go this route, makes for a compound that can do some repair work yet still do a good job of refining the edge. Once you get into single grit compounds in the low to sub micron range, they become much more limited as to what they are capable of. The honing compound I include with my block is multi grit (two sizes). Did a lot of testing and the multi formulas consistently outperform the single grit for anything but the brightest of finishes.

 

[Obsessed with Edges]

Re: Flexcut,

Flexcut's own site mentions their product is a blend of aluminum oxide and titanium oxide. I was web-searching into what advantages are lent by the titanium oxide; it's apparently used by some manufacturers of alumina ceramics as a coating or additive for alumina (aluminum oxide) to make it tougher or less friable, i.e. less prone to fracturing or breaking down during use. Titanium oxide by itself isn't very hard (ranks about ~6 on Mohs scale, as compared to about ~9 for alumina), so it might not be included as a secondary grit in the mix, with only the grit grade of the aluminum oxide being the primary influence in the finish left. I don't see any mention in web-searching of TiO[SUB]2[/SUB] (naturally-occurring form of titanium oxide) being used as an abrasive itself. Many more mentions describing uses as a pigment, or for the toughness-enhancing qualities described as above.

Edit (5/30/2014):
Flexcut's site is back up, after having been offline for a few days. Here's their description of the compound, quoted below:

(Quoted from site: http://www.flexcut.com/pw11-flexcut-gold-polishing-compound/ )

"Designed for quickly maintaining a sharp edge, Flexcut Gold Polishing Compound has been specially formulated to apply like a crayon. Its blend of aluminum and titanium oxide provides a balance between aggressive removal of hardened tool steels and offers a high-color polish. 6 ounce bar."

David

 

[HeavyHanded]

I recall reading once a description attributed to the folks at Flexcut stating a range of abrasives the smallest being .25 micron. I no longer take anything for granted without breaking it down and viewing first-hand.

One can learn a lot by using compounds on a lapping board as a slurry, this tends to reveal the true size range of the abrasive, might even make for a more pronounced scratch pattern than if the same abrasive were blended in a waterstone. Certainly far more abrasive than if used on leather or paper. The Flexcut is noticeably more aggressive than the Ryobi or Sears white, or .5u CrO, though when used on a strop, this distinction becomes considerably less pronounced.

 

[Obsessed with Edges]

The extra aggressiveness, as related to the assumed small grit size, may be related to added toughness of the grit, if that's what they're doing with the TiO[sub]2[/sub]. I just thought it to be interesting, in the various ways all these things can be tweaked for performance. Something new to think about, and keep us all guessing, it seems. It may be Flexcut is still utilizing a range of grit sizes in their mix, but maybe it's all AlOx grit.

I've noticed, in using something like Simichrome polish (aluminum oxide @ ~9µ, as stated by it's mfr) on a strop, it seems to show greater friability; at least in how it seems to work. Starts out very, very aggressive, removing a ton of swarf fast; then it tapers off and starts to polish to a higher degree, but not so aggressively, as if the grit is breaking down. This may be what some manufacturers are looking to control, in using the TiO[sub]2[/sub] to slow the breakdown of the abrasive (speculating).


David

 

[HeavyHanded]

I'd assume the Flexcut is all AlumOx of varying sizes, but could be wrong.

I generally attribute the changes in grinding characteristics when used on a strop to the surface being loaded up, rather than the abrasive breaking down. One thing that I observed when using different abrasives on a hardwood lap is that they maintained a very aggressive character for a lot longer than I'd anticipated, mostly related to the slurry consistency and not the amount of time in use - and this with quite a bit of physical pressure far in excess of a conformable strop. A quick agitation with a finger tip often restored any lost aggressiveness, but again that could just be turning over hammered particles...

Just a gut feeling, but the pressures exerted when using most strops (even paper over X) is probably not enough to damage most abrasives, even SiC - would be tough to pin this down and the remedy is the same either way - fresh abrasive on a refreshed surface.

Lots going on down there.

 

[Obsessed with Edges]

The Simichrome apparently breaking down is in stark contrast to the white rouge (from Ryobi) I've used, which stays consistently aggressive for it's stated grit size (2-5µ), and continues to both strip burrs and polish like nobody's business. That's the big difference I've noticed between them. In terms of how each performs, the Simichrome starts out 'bigger', but finishes much 'smaller' than the other AlOx (Ryobi) compound I've used. I'd considered loading up as a possible issue with both of them, and the Ryobi strop looks like it should be clogged (based on how black it gets, and how fast), but it just keeps on working as well as ever. This is why I suspect there's an additional something going on with the Simichrome compound.

There are grades of AlOx that some manufacturers design friability into, and they characterize degree of friability as part of the specs for them. Some even have a reputation for being brittle (this is where some have introduced the TiO[sub]2[/sub], to control or minimize brittleness, depending on application). The more I read about AlOx abrasives, the more similar they appear to steel varieties, with wide-ranging physical properties based on how they're manufactured and processed.

But, like you say, if they do slow down, that's easy to remedy with another application of compound (maybe a little cleaning too).


David

 

[dkb45]

I went through and bit the bullet to do some stropping, and my green and gold are both finer than 2 microns, or they were just fine enough to induce slightly more polish while also giving an even sharper edge.

I also think my issue with the Flexcut strop was not enough compound on it. There was barely a coat over the whole thing. I scrapped off as much as I could then gave it a once over with the wire brush to remove anything caked in, and gave it a vigorous coating. It is now working better. I CAN NOT get oil to work on reconditioning it when the compound is spent. The oil just absorbs right in where I first touch and doesn't move. I think that is because it is going right into the leather and not touching compound.

 

[Obsessed with Edges]

I went through and bit the bullet to do some stropping, and my green and gold are both finer than 2 microns, or they were just fine enough to induce slightly more polish while also giving an even sharper edge.

I also think my issue with the Flexcut strop was not enough compound on it. There was barely a coat over the whole thing. I scrapped off as much as I could then gave it a once over with the wire brush to remove anything caked in, and gave it a vigorous coating. It is now working better. I CAN NOT get oil to work on reconditioning it when the compound is spent. The oil just absorbs right in where I first touch and doesn't move. I think that is because it is going right into the leather and not touching compound.

An easier way to apply it would be to moisten a clean rag/cloth with the oil, then use that to wipe down the strop. A paper towel could also be used, though sometimes they'll tear up a little bit, and leave paper lint all over. Easier to get an even coat when using a rag this way, when it otherwise soaks in so fast when applied directly. Barely any is needed anyway, so applying it with a moistened rag will be just enough. Could also use something like a sponge or foam wax/paint applicator in the same manner; all new & clean of course, to prevent contamination.


David

 

[HeavyHanded]

I went through and bit the bullet to do some stropping, and my green and gold are both finer than 2 microns, or they were just fine enough to induce slightly more polish while also giving an even sharper edge.

I also think my issue with the Flexcut strop was not enough compound on it. There was barely a coat over the whole thing. I scrapped off as much as I could then gave it a once over with the wire brush to remove anything caked in, and gave it a vigorous coating. It is now working better. I CAN NOT get oil to work on reconditioning it when the compound is spent. The oil just absorbs right in where I first touch and doesn't move. I think that is because it is going right into the leather and not touching compound.

Personally I avoid using oils on leather strops unless I'm reconditioning it and the leather really needs some help. In that case I'd stick with products made for leather. You run into situations where there's too much mobility of the abrasive and it stops working properly. This applies to paper and when using hardwood lapping boards as well, but is a lot more forgiving in those applications relative to leather.

You can rub a few drops of mineral oil into the block of compound and apply that way, or just press hard and make a grid across the surface. I used to keep my compound in a baggie with a few drops of oil, give it a shake and the entire surface of the block will soften a little and go on a lot easier.

 

[dkb45]

An easier way to apply it would be to moisten a clean rag/cloth with the oil, then use that to wipe down the strop. A paper towel could also be used, though sometimes they'll tear up a little bit, and leave paper lint all over. Easier to get an even coat when using a rag this way, when it otherwise soaks in so fast when applied directly. Barely any is needed anyway, so applying it with a moistened rag will be just enough. Could also use something like a sponge or foam wax/paint applicator in the same manner; all new & clean of course, to prevent contamination.


David

Never thought about this way. Makes a lot more sense.

I had just read a few people say that oil like mineral oil or olive oil is good to recondition compound on a strop, I have just always used a method of abusing the strops, through overuse of the wire brush to rubbing it against a brick to digging a putty knife in to scrape as much off as I can. This same strop has survived well over a year of this abuse, I'm just planning on replacing the whole thing when I can get new hard leather.

 

[HeavyHanded]

Here's the low down on Flexcut particle range. There were some larger pieces but I couldn't be sure that they weren't clusters of smaller particles, so settled on an image area that is very representative of the whole and with particles that are clearly one piece.

The size range seems to mostly be from 6U on down to sub-micron. The smallest I could get a respectable line on were under .5u, so I can imagine the smallest are probably in the .25 range.

Am no expert, but that looks like aluminum oxide through and through. From what I've read, the titanium oxides wouldn't be visible as a separate mineral or coating under these conditions, though a real expert might be able to spot some telltale characteristics. It might very well be what gives the India stone its color and impressive longevity relative to the pale grey (white) forms of alumox. Am not sure I've come across a honing compound marketed specifically for carving/hand woodworking that wasn't a multi-grit formula.

Am sure Flexcut isn't going to share, but entirely possible the larger pieces are a more friable variety and the smaller ones are more durable? You can loose your mind noodling around with this stuff...

Aluminum oxides
Aluminum oxide consists of blunt shaped grains and is very tough in its lowest refined form. During the melting stage in the production of aluminum oxide, the crystalline structure and its chemistry can be controlled, allowing the manufacturer to produce a family of products that perform differently. Aluminum oxide is produced in a variety of types, and its versatility makes it the most commonly used abrasive.

White fused aluminum oxide is softer, or more friable, than other abrasives. It has high chemical purity (more than 99 percent Al2O3) that gives it an aggressive, cool, fast-cutting action. White-fused aluminum oxide holds its form well. It is used to grind heat-sensitive alloys. These applications make use of its friability and the fact that it cuts without generating high heat. This grain is also used to gring heat treated tool steels, high speed steels, and for internal grinding wheels.

Aluminum oxide fused with chrome oxide is a pink abrasive that is used in grinding applications that require slightly more toughness than white fused aluminum oxide. The chrome oxide component of the abrasive enhances its grinding capacity. Although friable and cool cutting, aluminum oxide fused with chrome oxide exhibits strong form-holding characteristics. It is used for precision, broad surface and toolroom grinding on hard alloy steels.

Brown fused aluminum oxide includes 2 to 4 percent titanium oxide (TiO2) to enhance toughness. (Titanium oxide is also known as titania.) This is the most widely used abrasive, and is used to grind high-tensile-strength materials, and for rough grinding, deburring and snagging, as well as to cut low-alloy, ferrous materials.

Low titania brown fused aluminum oxide has 1 to 2 percent TiO2 content, and is used in bonded or coated applications that require an abrasive that is slightly tougher than white aluminum oxide. Reducing the titania content reduces the abrasive's toughness, but increases its friability.

 

[Chris "Anagarika"]

Martin,

Thanks!is this same Flexcut Gold you sent for test sometime last year?

 

[HeavyHanded]

Martin,

Thanks!is this same Flexcut Gold you sent for test sometime last year?

Chris, that's the stuff. Hands down my favorite of the manufactured honing compounds.

 

[Obsessed with Edges]

HH, thanks for the follow-up images of Flexcut grit. I've no idea if Flexcut's larger particles are more friable than the smaller ones; another mystery to ponder.

That quoted text you referenced looks familiar; I think I saw the same article or description in my looking around, but don't remember which site it was on. I completely agree, it's easy to feel like my brain is being processed, the more I read about this stuff. The potential upside is, it seems there's a whole world of possibilities with AlOx compounds out there, and so much more experimenting to do.

I was thinking some more yesterday, about the Simichrome grit. When I've used it on strops, it takes on a very 'chalky' character after the suspension dries; it's pretty dusty stuff. And based on how it appears to work, it's very easy for me to imagine it crumbling into finer dust as it's used, just as a piece of chalk would do. I haven't been left with that same impression, in seeing how differently the Ryobi white rouge works. The waxy binder of the Ryobi compound obviously eliminates the 'dusty' nature of it, as compared to the Simichrome. But, they really do perform differently in use.


David

 

[dkb45]

I think I figured out another reason why my edges aren't cutting like the Worksharp edges. The scratch pattern on a powered sharpener is generally vertical, but the best way for me to control the angles by hand is to draw base to tip. I have tried tip to base, but I can never get the angles right on it.

I am enjoying the results of sandpaper, but I still miss my belt sander. If I was as proficient then as I am now, I would have never touched anything else. I was able to get a mirror finish better then but my angles were off, and I didn't know about the feather touch for finishing. I also didn't have Flexcut gold then, which has helped a lot. Now that I have the skill, proper tools will make me that much better. I loved those really gentle convex edges.

 

[Student762]

I use a silicon carbide stone that belonged to my grandfather, a 600 grit sand paper and then a leather strop and get hair popping all the time. never seen the need for anything else. I do have a diamond that I use for an axe if need be

 

[dkb45]

I use a silicon carbide stone that belonged to my grandfather, a 600 grit sand paper and then a leather strop and get hair popping all the time. never seen the need for anything else. I do have a diamond that I use for an axe if need be

For some reason I can't leave it at sharp. If it doesn't reach the level of absurdly sharp (I aim for stupid sharp) it is worthless for me. Really stupid standard, but since my knives get little use I can always show them off. My knives are hardly users.