Balsa Strop - Paste or Spray Compound?

Kid Shamrock

Kid Shamrock

Joined
Feb 20, 2012
Messages
221
Using a balsa strop, which works better, spray or paste compound? Or is there no real difference? :confused:
 
Spray or paste is of no matter. What matters is having a uniform particle size distribution , and concentration.
 
I think the biggest downside to the diamond pastes is the ease (or lack of same) of application. At least with DMT's pastes, they tend to be a bit gummy & sticky during application, which sometimes makes it more difficult to get an even distribution on wood. The oil suspension (assuming) also makes them pretty sticky in use, for the first couple of days, until it dries a bit more. I haven't yet used the sprays, but I'd think application should be much simpler with them.


David
 
I don't believe that, within reason, 'distribution' is all that important...
(I'm using 'bold' here to stop the extremists.)

In the same way that an interrupted diamond surface is effective, as long as there is a generally sufficient coating of abrasive across the strop in contact with the edge, your stropping will be effective. Obviously if all your abrasive is located at one end you will be wasting time and energy at the other end. But it's reasonable to believe that if there is an ordinary coating worked over the surface of the strop, it's not going to make a difference if the compound is heavier at one end, or heavier in spots, so long as there is compound generally covering the strop.


Stitchawl
 
My main issue with distribution is just in the relative messiness (& tediousness) of it. There's always a little bit of waste involved, as the paste will cling to whatever's used to spread it (oftentimes, my fingertips); I hate to waste any of it. I'm not concerned about getting a perfectly thin & uniform layer across the surface, but instead just getting a relatively wide coverage without using excess compound. On a relatively grainy & porous surface, such as balsa and other softish woods, the paste tends to sink in & cling to a relatively small area very quickly, and spreading it thinly from a small daub of product is a little more tedious.

I was just emphasizing the liquid sprays would seem to be a lot quicker in application, and getting down to business. The sticky nature of the paste before it completely dries also slows that down a bit, as it tends to cling to the blade if it hasn't fully dried on the strop. This means I usually wait a couple days, before attempting to use a strop with a new application of paste on it.


David

stitchawl said:
I don't believe that, within reason, 'distribution' is all that important...
(I'm using 'bold' here to stop the extremists.)

In the same way that an interrupted diamond surface is effective, as long as there is a generally sufficient coating of abrasive across the strop in contact with the edge, your stropping will be effective. Obviously if all your abrasive is located at one end you will be wasting time and energy at the other end. But it's reasonable to believe that if there is an ordinary coating worked over the surface of the strop, it's not going to make a difference if the compound is heavier at one end, or heavier in spots, so long as there is compound generally covering the strop.


Stitchawl
Click to expand...
 
I use .5 micron diamond spray on my balsa strop. I apply it by finger, though, so my coating is probably a little thicker than it would be using the sprayer. But it does give me a chance to even the coating out more than the sprayer would do.
 
A harder surface-MDF, or even cast iron or steel should work better than balsa wood. Balsa is very soft.
 
If your spreading any compounds with your fingers you need to be wearing disposable gloves so as not to contaminate the strop...
 
Sadden said:
If your spreading any compounds with your fingers you need to be wearing disposable gloves so as not to contaminate the strop...
Click to expand...

By the standard set in the pics you've posted of your edges, I can see your motivation for doing so. :D

In reality, any strop that's sourced, manufactured, stored, shipped and handled outside of a true cleanroom environment is already contaminated by default, from the git-go, when comparing to sub-micron polishing grits. A simple piece of balsa or any other wood or leather picked up at a craft store or home center will already be 'contaminated' with dust that's grittier than what's on my fingertips (I wash my hands before & after applying the compound). That doesn't even consider the stuff picked up on the way home from the shopping trip for the materials, here in the desert southwest, where ever-blowing & settling dust is a fact of life. Only possible way not to contaminate any of it, is if working in a semiconductor-grade cleanroom (I used to, BTW). Any use of these materials in the 'real world' renders it essentially moot; there's no escaping contamination in the absolute sense. This is why I haven't worried about going any finer than 1µ anyway. I can visually see some benefit to my edges from going that low, even in my 'dirty' environment. Anything finer would be a waste of effort and $$, for me. :)


David
 
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Obsessed with Edges said:
My main issue with distribution is just in the relative messiness (& tediousness) of it. There's always a little bit of waste involved, as the paste will cling to whatever's used to spread it (oftentimes, my fingertips); I hate to waste any of it. I'm not concerned about getting a perfectly thin & uniform layer across the surface, but instead just getting a relatively wide coverage without using excess compound. .............
David
Click to expand...

Got it! :thumbup:

There really IS a lot of waste when using most bar compounds, and especially when using them on porous surfaces, or those folks who spread it on like cake frosting. Quite a lot of waste when using sprays. In fact, I can't find ANY reason to use sprays at all! The cost is much higher and the wastage greater. I stopped using bars when I discovered liquids and soft pastes from Hand American 15-20 years ago. (Except for a small chunk of Chromium Oxide the size of a sugar cube that I carry in my backpack when camping, just to have something to do with my hands at night around the fire.) And pastes have replaced any size spray I may have tried and used up much too quickly. With a liquid or paste, just a couple of pea-sized dots is more than enough to cover a large bench strop, and with no need to re-charge for a hundred or so stroppings, and goes a long way if one isn't a professional sharpener doing dozens of knives every day. Thinking about it, I probably don't re-charge more than once or twice a year!

I've stated it before but it bears repeating; I bought two 8oz bottles of liquid Chromium Oxide from Hand American more than 15 years ago, maybe now it's 20 years ago, wasted quite a bit learning about it, and still have one and a half bottles left. I figure I've only got another 10-15 years left to live, so I doubt I'll even finish the first bottle before I check out. But 'I' definitely get better results when I strop on harder surfaces rather than balsa or cloth (but that's just me,) so it's now easier for me to spread a tiny amount of liquid or paste over the entire strop surface, as I can use more pressure to move it around.


Stitchawl
 
Well let's look at this a bit more precisely. It is largely a matter of viscosity and particle adherence. A thick paste will be hard to spread, more difficult to apply uniformly and not the best approach. A lower viscosity paste or formulation will spread more easily.

An oily paste is also more of a pita, requiring more extended drying times and because it doesn't truly dry, it is more likely to attract airborne contaminates. It also is not to be used on waterstones as it will damage them.

Bars and greaseless compound tubes have their place - primarily for powered applications like buffing wheels, but there is considerable waste using the current generation of products. They are quite cheap, so for some applications, it is appropriate. I'll ignore the various formulations out there in any detail as this is beyond the current topic.

A water soluble gel is a better 'solution', however even here some gels - including my own, dry slowly.

Sprays do give a uniform coat more easily. Not a particularly heavy coat and the overspray is somewhat wasteful unless you use another substrate to capture the overspray. It is easy to apply and 'clean' in the sense that no residue is present if it is a basic slurry formulation. A light spray is often perfectly adequate to achieve results, so even with overspray very little compound is required. If you are doing a few strops simultaneously the percent overspray becomes negligible.

To me a properly designed emulsion formulation is ideal and what I use on my newest products - the result of a few years of research. I use a glove to apply it so there is NO overspray and the entire application dries quickly with NO residue left on the glove (at least none visible with the naked eye). Essentially a zero loss solution. It is also a permanent suspension so a high degree of uniformity is achieved with little effort.

For a balsa strop I suggest the emulsion or spray formulation. To minimize overspray, hold the bottle close enough so that the spray pattern width matches the strop width.

---
Ken
 
Kid Shamrock said:
Using a balsa strop, which works better, spray or paste compound? Or is there no real difference? :confused:
Click to expand...

IMHO is going to be dependent on the specific product more than a blanket statement. In my experience all abrasive particles will perform better if used with some form of binder/vehicle opposed to a dry particle under the same conditions. Some diamond pastes are a bit too oily for some surfaces, some grease (crayon) blocks are too hard for some surfaces, etc - so is a question of trial and error to find what sticks to the balsa in a way that gives best results without needing additional tweaking. On balsa I've found a paste to work very well, and many crayon types work fine if broken down with a touch of oil and allowed to soak in or just use a conservative amount of oil to begin with.

I spent a lot of time manufacturing a compound that would work best applied to paper - small changes in the binder/vehicle will have a noticeable effect in use. As a nice side-effect, my compound is so hard it can be left in a drawer or on a benchtop and brushed off before use if its accumulated any debris - I can't be bothered with gloves or baggies for everyday sharpening.

Too much mobility and the abrasive will lack bite, too little and it will load up quickly.

I stopped using balsa after a bit of experimentation and switched to oak. Regular crayon compound strung out with a few drops of oil make a very crisp edge when worked on oak or other hardwoods, is more like a fine hone than a strop though can be a little fussy with the specific viscosity. Ultimately I wound up with paper over a very hard surface for max versatility and convenience.
 
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Well they used to do surgery without gloves, but that went out of fashion during the (US) civil war. Do you HAVE to use gloves? No. Just use really clean hands if you must. This will waste more compound on your hands rather than on the strop. As you go to finer compounds the potential for contamination increases. Gloves are even used by people preparing food, doing dishes and even cleaning toilets, not just surgeons.

Do I personally use gloves with pastes and emulsions? Of course. For the same reason I don't soak all my stones in one bucket. Cross contamination. Call me a purist for this. To me doing anything less than this would make me feel the need for brain surgery :)

I clean my knives between stones and between strops too. It just makes sense.

HeavyHanded, I think we are on the same page here in terms of optimizing our compounds for their intended uses, coming up with a proper vehicle for the substrate.

Here's a video of me applying CBN emulsion to a linen belt. Notice how much 'waste' there is on the glove - none :)

[video=youtube_share;IxJMSHR907s]http://youtu.be/IxJMSHR907s[/video]

---
Ken
 
So what do you do about the dust in the air? Because that's far more abrasive and ALWAYS around. Unless of course you sharpen inside of a clean room.

Point is, why worry so much when all the proper steps are not taken. I deal with mold and asbestos daily and have been Trained in the remediation and decontamination required to do these things properly. I highly doubt you have negative room pressure, HEPA filtration, tyvek suits, gloves and boots taped at the joints, full face respirator, and decon chambers set up. So basically the gloves are moot point in the cross contamination issue.
 
When I get in a batch of strops I am loading 5+ strops at a time typically , so care needs to be taken in order to not cross contaminate coarser abrasives onto finer strops , an irreversible error.


-I start by cleaning the work area , wipe down everything with a clean damp rag.

-Then lay everything out and labeling it all (strops , and individual baggies)

-I then wash my hands and arms , and put on clean clothes.

-Then wearing gloves I start with my finest strops and move onwards to my coarsest. That way any cross contamination is of a non issue. I handle the strops only by their edges , never the stropping surface itself.

-Allow to air dry

-Put each strop in its corresponding plastic baggie.


This is solely to stop large abrasives from contaminating finer strops ,however I doubt there are 15u particles floating around the air in my apartment. Even if there were , would they be hard enough/abrasive enough to scratch steel? I guess not as all my strops would be leaving 15u scratches instead of the much finer scratches they do leave.

 
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Jason, given your training, you should know better. I've spent 25 years working in operating rooms, infectious disease environments and chemically hazardous environments and I'm still around, so I must have learned something about contamination. Yes this did include brain surgery too :) Given a biology background, I studied microbiology before you were even born. I've also done metrology studies and dealt with computer chip manufacturers' clean room environments too. And high radiation environments too.

Are there particulates in the air? Of course. Some rather large depending on your environment. Some abrasive and some not so. So obviously leaving a loaded strop 'around' in this environment is a bad idea. The inside of a ziploc baggie is pretty close to a clean room environment and so it is logical to store the strops there between uses. It is an affordable alternative. Same with disposable gloves. EVENTUALLY you will contaminate your strops to an unacceptable level, just like you will eventually get your hands dirty and need to wash them.

There is an issue here of RELATIVE contamination. Even more likely than airborne contamination is direct physical contact - eg dirty hands. If you walk into a room with a patient with a wound infection, you don't get infected. If you stick your ungloved hand in it and transfer the bacteria to a membrane like your eyes, etc you run a much higher risk of contamination. Even if you stick yourself with a needle used to draw blood from an AIDS patient, you are not GUARANTEED to get infected. There is an issue of RELATIVE contamination here I am trying to explain by example. Similarly, you MUST wash hands between patients after examining them to not spread infection between patients or to and from your own bacteria. So when you wear your NIOSH approved mask for particulates, the warning label will tell you to leave an area if the particulate levels are EXTREMELY high. The masks are effective in range of concentrations. You should know this. When you are walking down the street, perhaps there are a few asbestos particles floating around, but we don't go running around in a bubble boy outfit.

If you have bacteria in a wound, it is considered a clinically significant infection if the bacteria count exceeds 10 to the 5th power (100k) bacteria per gram of tissue. One or two bacteria is considered insignificant. This is exactly analogous to the grit contamination issue. We are SURROUNDED by bacteria in the air yet we don't run around in Hazmat suits.

So we deal with relative contamination. When we serve food, it is sitting in air with bacteria floating around it. The silverware and glassware is relatively clean from the last person using it.

So in short you are confusing obvious gross contamination with a minor degree of contamination and it is best IMHO to minimize contamination. Hardly a moot point. Pretty basic stuff.

---
Ken
 
Here's what I wear when I start sharpening at 1.2 million grit :)


1399867587-hazmat.jpg


Note the obligatory protective grip :)



---
Ken
 
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Well, sadden

Throw a few variables in and things change and start to make sense. Your original statement was not as clear.

Ken,

I'm not here to argue with you and while mostly correct your post takes it to the next level, which is about 10 levels past sharpening ;)

Your right, I do know those things but your bacteria example could be better.
 
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