Thread: Thin White Line

Ive been searching the forum for 24hrs now without finding a possible explanation for my conundrum.
This is probably because I cant figure out what to search for.
Any veteran who recognises this and can point me to an old thread is velcome.

Ive honed up an old Pradat Brun via bevel setting on a Naniwa 1k followed by polishing on Naniwa 5 and 8k.
Similar progression on a new Gold Dollar gave good results.

Problem:
The top third of the edge is not sharp. The middle and heel is good, but not the toe.
Under a radioshack microscope the edge gets a thin white line, like a halo running parallell to the edge along the not sharp toe.
The same 'phenomenon' is not present along the sharp parts and nowhere on the gold dollar.

Does anyone recognize what this is? Have an idea? A theory? or a link to one of several older threads where this is discussed in depth?
(Im a bit miffed actually because searching usually gives plenty of results whenever Ive had problems/questions or just been looking for info but no luck this time.)

Thanx for reading.
/H

Just a guess, but maybe a warped blade? Try rolling x strokes and watch the water pattern on the hone.

The white line is normally indicative of a Burr/Folded edge, this should however be very obvious.. Take your thumb nail and lay it flat on the blade face above the line, draw the flat of your thumb nail down from spine to edge and see what grabs, try the other side... You can also use a pin point.

A TNT will also show this, which is why I am hesitant to say that you have a Burr because I am assuming you are using a TNT to test the bevel set anyway...

A pic would of course help, or at least a description of what the TNT feels like..

Your examination of the opposing spine sections that are not sharp may yeild some clues.

It was very common in the day for those that didn't know how to sharpen to use two hands and place a finger on the toe to push it down. They would put their grubbing little finger in the hollow section. The resultant spine deterioration is hard to see, but is visible.

Consider that as a possibility.

Originally Posted by hakan

The top third of the edge is not sharp. The middle and heel is good, but not the toe.
Under a radioshack microscope the edge gets a thin white line, like a halo running parallell to the edge along the not sharp toe.
The same 'phenomenon' is not present along the sharp parts and nowhere on the gold dollar.

If you have a line running parallel to the edge, my first thought is that you are not making adequate contact with the hone on that part of the edge. Is the line present on both sides or just one? Are you using an x-stroke? Have you tried circle strokes? Are you familiar with the bevel marker test? If you just lay either side of the blade flat on the hone, does the blade appear to be flat and make full contact with the hone?

Hakan;

I believe what you have is a condition where the original edge has become rounded off and although you are honing properly, you need to work the geometry back further to (re)obtain a correct edge.

To illustrate this, I have put together a small graphic (somewhat exaggerated for clarity).

At (A) you see the original, correct flat-honed cutting edge of the straight razor.

At (B) you see that same cutting edge after long use (also caused by heavy stropping on pasted strops, especially if the strop is not completely taught or is being slightly 'lifted' at the end of the stropping strokes).

At (C) we see the edge after some amount of honing. The areas in RED are where the rounded edge has correctly met the flat of the honing stone. In my opnion these areas are the 'halo' you are referring to. As you can see, due to the rounding of the blade edge geometry it will take more honing to actually bring those flat areas together into a proper point again. Until this is done, you still have the original (blunt) edge which caused you to start honing in the first place. Unfortunately, it is easy to feel the results of this, but much more difficult to actually 'see'.

- Ignatz

speechless...

I dont know how to say thank you for 5 good, kind answers in this short time. Or any time!

Ill go through them all and try to get some pics.(every thread is better with pics, right? )

Im a total noob to honing, although Ive had success with everything Ive tried so far thanks to all the amazing articles and tutorials found via the wiki on this site. Not to mention the forum.
Hence, no mention of how the TPT felt. I dont know how to describe it coherently, yet.
Bevel was set with Lynn's circular motion 'technique', further polishing with x-strokes, I believe the blade is slightly warped but every blade I have ever seen has been, ever so slighly, warped in some way.
Maybe this one is more than usual.

Thank you again for all the tips. Ill be back with a deeper analysis and maybe some pics after Ive gone through this pot of gold.
And, since Im an NFL-junkie, after the football...

/H

ps/ go McNabb! /ds

My two guesses are pretty much the same as what's above.

Either you overhoned the toe and developed a wire edge OR you did not hone the toe enough and the bevel there is not yet set. The various tests GSSixGun mentioned should help you determine which is the problem.

So Ive spent some time going through these tips.

Originally Posted by rodb

Just a guess, but maybe a warped blade? Try rolling x strokes and watch the water pattern on the hone.

There is a slight warp, but I feel it's too small to make that part so completely dull. I may be wrong.

Originally Posted by gssixgun

The white line is normally indicative of a Burr/Folded edge...

No burr. felt around with a sewing pin, saw this on a video somewhere, from spine towards edge and cant feel a thing.
TNT is, of course, like a breadknife on ice. I must have missed feeling the top third when setting the bevel or blunted it later.(and accidentally wrote tPt in my earlier post...)

Originally Posted by AFDavis11

Your examination of the opposing spine sections that are not sharp may yield some clues.

It was very common in the day for those that didn't know how to sharpen to use two hands and place a finger on the toe to push it down. They would put their grubbing little finger in the hollow section. The resultant spine deterioration is hard to see, but is visible.

This feels/looks like a possibility. Im going to attempt to take some close-ups of the spine to get some feedback from someone who knows what they are doing e.g. coming up in this thread.

Originally Posted by Utopian

If you have a line running parallel to the edge, my first thought is that you are not making adequate contact with the hone on that part of the edge. Is the line present on both sides or just one? Are you using an x-stroke? Have you tried circle strokes? Are you familiar with the bevel marker test?

The thinwhiteline/halo is present on both sides. Im gonna do the "bevel marker test"

In an attempt at analysis I did a quick little pyramid on the 5k/8k to watch the "wake" on the hone and see if the tip got sharper.
Still dull as a breadknife and to better se the "wake" I made a little slurry with a small dmt 1200 which made it much easier to see the wake and Im either rocking vertically at times in my x-stroke or the hones arent flat anymore or both.

I lapped the hones before honing the Gold Dollar which turned out very good.

Im going to lap the hones, do the "bevel marker test" and then go from there.
Is this sound problem solving?

Dont expect another update for a week since Ill be travelling.

Thank you, again.
/H

ps/ I tried taking some pics of the culprit but they all turned out crap. Ill have another go at it later. /ds

Set the bevel correctly. you should be ok then.gl