WOW this is frustrating!

[Josh]

So I noticed a random, not all the time, stropping/buffing effect when doing mirrored edges which would extend 1/16″ to 1/8″ up above the shoulders of the edge. Here are two knives I did at the same time, one has the effect one doesn’t (second one has the buff marks above the edge)

So more recently, I was sharpening some EXPENSIVE knives that I taped off everything but the very edge:

One of my theories was that the strops were rounding over the shoulders of the edge when I lowered the angle 3 dps to strop and that was causing the buffing marks, and to some extent, I think that is correct. But on this particular knife, I switched over to use ONLY my balsa strops and matched the existing angle from my 10k choseras, so that effect would not happen. The mirrored edge turned out great!

But look what happened!! SUPER frustrating… any ideas? This “tape line” is only visible in certain light but it is definitely there and won’t come off even w/ acetone. I think it is coming from the abrasive slurry from my waterstones when wiping it off. note that I was VERY careful to always use a clean section of the paper towel only once and do it in such a way so as to not allow the slurry to rub on the metal blade

This was “only” a $1k dollar custom (Shirogorov 95T). But this is a huge issue. Look what happened to a $9k Shirogorov Coordinal (note the “wavy” appearance was where I had taped it off and cut the tape unevenly”:

for this reason, I am considering investing whatever I need to in going completely over to lapping films after the diamond stones. Any thoughts much appreciated!

[Aaron kimpton]

Based on your previous posts I have changed to lapping films after ceramics.

[Daniel maloon]

Ya I’ve noticed the same happening before when using leather strops. On certain blades the typical lower by 2 dps doesn’t work due to the thickness of the blade. On thicker blades you polish the shoulder.

[otaku19]

I also noticed from my Edge Pro days, that when using choseras, it was extremely difficult not to scratch the blade regardless of how careful I was to tape it off. Rinsing the blade off between flipping helped out a lot, but this would take some extra time with the Wicked Edge. I get a really nice polish without moving the arms when I strop.

[wickededge]

Is it possible that slurry has found a way to get under the tape? It might explain the line you’ve got place there. You might also consider changing your technique for wiping the blade to an upward motion until it’s mostly clean. I think the balsa strops have enough give to create the effect you’re seeing. It would be worth coloring in part of the flat of a cheap blade and stropping with balsa to see if the strops remove marker on the shoulders and some of the flat.

-Clay

[Josh]

Is it possible that slurry has found a way to get under the tape? It might explain the line you’ve got place there. You might also consider changing your technique for wiping the blade to an upward motion until it’s mostly clean. I think the balsa strops have enough give to create the effect you’re seeing. It would be worth coloring in part of the flat of a cheap blade and stropping with balsa to see if the strops remove marker on the shoulders and some of the flat.

those are great ideas clay, I will explore them! fyi I was using that exact method for wiping the slurry away with a clean paper towel each time.

[SHVentus]

Josh,

What about using Frog Tape instead of blue painters tape? It holds a better paint line, preventing bleeding by the paint.

[SHVentus]

BTW, I’ll give you $100 for that “ruined” knife. :cheer:

[Todd Simpson]

I also think that Frog tape would be a better choice. I was also thinking that a plastic coating like plasti-dip would work, but it takes a fair amount of time to dry fully. How about nail polish? you could just hone through it on the bevel and remove the rest with acetone at the end.
In any case, make sure you clean the blade with acetone first so that whatever you use adheres.

[Aaron kimpton]

I think for all the extra time one spends taping and cleaning durring the stropping. It would be simplified and cheaper to use laping films

[CliffCurry]

So I noticed a random, not all the time, stropping/buffing effect

Question Josh, it looks like these are stonewashed blades? My thought was that could be a big part of it. A thin stonewash could be effected by a slight slurry and stropping on the shoulder.

Painful brother, I feel for ya on this one… :dry:

[Steven N. Bolin]

I think for all the extra time one spends taping and cleaning durring the stropping. It would be simplified and cheaper to use laping films

Give me ONE pair of handles with glass platens and a variety pack of lapping film… That’s where I’m at… For so may reasons!

[tcmeyer]

I’ve been using glass almost exclusively now for about a year. The film is expensive at $1 – $3 per strip and I can’t imagine living with only one or two grits or having to peel the film off to make a grit change. Love it, but I have six pairs of blocks with glass on both sides, so I have my choice of every diamond grit and an equal number of silicone oxide grits. I’m thinking that you’d want three pairs of platens for film.

I’m making a set right now with brass platens, thinking that a material softer than steel wouldn’t accidentally scratch the side of a blade. WE’s aluminum platens serve the same purpose. I take them to a flat plate and lap them with sandpaper. I’m also trying a pair where I’m applying paste right to the brass, thinking that the diamonds will embed themselves in the brass. Don’t yet have any data to report back.

The film doesn’t care what material you use for platens. It just needs to be flat so that the film lays down flat, without any hump or bumps. A speck of dirt will cause a nasty bump which the first edge will try to remove.

There’s an interesting effect that happens when you pull the film off of a platen. It takes quite a bit of force, which stretches the film and the adhesive backing. Unfortunately, the film is elastic, but the adhesive is not, so when the film is free, it retracts, trying to go back to its original length. Since the adhesive is not elastic, it does not retract, leaving the adhesive side longer than the film side. This results in a curl. Probably best to lay them out straight and lightly stick ’em to some temporary surface. If you wanted to reuse the film, as you apply it, you’d have to re-stretch it to a length longer than the adhesive. Not difficult, but I’m not sure how flat it will be when you stick it down.

Not to mention the fact that the adhesive doesn’t like to release from the platen readily. If it separates, I think you’re SOL. Maybe if you change frequently it will separate more easily. Applying heat with a hair dryer will help.

[Josh]

Thank you all for chiming in! As I’ve been working through mirroring 3 CRK sebenzas I think the solution is to:

1. clean the vise real good
2. clamp the blade without any tape on it
3. wipe with a clean paper towel often in such a way that you are going up and away so you are never rubbing the abrasives back into the blade
4. use diamond lapping film
5. use balsa strops

[Marc H]

There’s an interesting effect that happens when you pull the film off of a platen. It takes quite a bit of force, which stretches the film and the adhesive backing. Unfortunately, the film is elastic, but the adhesive is not, so when the film is free, it retracts, trying to go back to its original length. Since the adhesive is not elastic, it does not retract, leaving the adhesive side longer than the film side. This results in a curl. Probably best to lay them out straight and lightly stick ’em to some temporary surface. If you wanted to reuse the film, as you apply it, you’d have to re-stretch it to a length longer than the adhesive. Not difficult, but I’m not sure how flat it will be when you stick it down.

Not to mention the fact that the adhesive doesn’t like to release from the platen readily. If it separates, I think you’re SOL. Maybe if you change frequently it will separate more easily. Applying heat with a hair dryer will help.

Tom, have you used the lapping film without the adhesive? Then you wouldn’t have the stretch problem. I’ve been wondering how well that non adhesive film stays in place on the glass platens. Does anyone have experience with the non-PSA lapping films they can share?

Marc

Marc
(MarcH's Rack-Its)

[Author]

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