Thread: How does Lapping actually work?

A perfectly lapped stone is not perfectly flat, there is the grit and the microscopic space between them. If it were perfectly flat it would be called glass. What we are attempting to do in lapping is make the tops of the highest layer of grit on the same plane, not really make the stone perfectly flat.

Many naturals and synthetics benefit from lapping with a much coarser stone, refracting the grit and cleaning the area around the grit to keep the swarf from loading up. Think sandpaper sanding drywall compound.
The 325 plate seems a good general lapping/refreshing hone for most stones, but experimentation for your stone is the key. Try different lapping grits and see what works best. And forget about dead flat, even glass is not really dead flat… it doesn’t matter.

this thread was helpfull...thanks for all the input guys

Euclid that is a silly thing to say. If you go down to a small enough scale nothing is perfectly flat and there is space between the particles/atoms. For the purposes of the example we are trying to get the stone "perfectly" flat. You are trying to achieve flat on a similar level of "flatness" that you want to be exhibited in your razor. I will agree with you in saying you are trying to remove crap from between the grits though.

The question was “How can you lap a 10,000 grit stone with a 250/400 grit sandpaper, and not have a bunch of scratches in it?” the scratches don’t matter as long as the scratches run parallel to the honing direction. It becomes a matter of aesthetics removing scratches on a hone. Lapping a stone to 8K is a waste of time, effort and 2 stones. Unless it increases performance and you will not know that unless you experiment with that stone.

Flat is a relative term, we are attempting, 1.to get the tops of most of the grit on the same plane, not all the grit. 2. Refract the grit. And 3.Unload/clog the grit, all at the same time.



Attached is a stone I pulled from the slow cooker it’s been soaking for a few days, I suspect/hope it may be a coti… maybe an old ark. It was somewhat yellow when it went into the soup.

Now I could flatten the dished side, it would be purely aesthetics, a waste of time, sandpaper and effort. Instead I will lap the bottom side and test for its cutting/finishing abilities. If you could lap the dished side so all the grit is at the same height and you held the spine on the hone you could sharpen on the dish side of the hone. How does a jointer/surface planer flatten a piece of wood? The cutter head is round, and the blades travel in a circular motion, no?

Many times we do thing just because others say to without asking why? I applaud Clarence for asking why? Get as much information, then do what he thinks is best for him, experiment and see what works. To blindly polish rocks to a mirror finish, just because… is not productive or skill building. Now that is silly.

How many threads have we read from novice honers who have done x laps on 1K-12k as instructed and can’t get a razor to shave? Was it sharp at 1K? No one ever checked, but he did the required laps.
We are not baking cakes.

And as for scratches, I do not see how they matter as long as the surface is overall flat to the bevel. Bevels are thin, but microns are even smaller. Dont forget the fact that In the case of the dished hone up there (after its smoothed out), the effect would be similar to a layer or two of tape on the spine. If you pretend the dish is smooth, and take an arc with the same width as a razors bevel from it, for most intents in purposes it will be flat. Now picture the full blade on it. Even for that distance, the stone is relatively flat. But for humor sake, extend the line of the bevels contact out, and it will pass just under the spine of the razor. The dish only really becomes noticable at the 2" mark, and then more so at the 3" mark. give it a try, scroll up and block of the monitor with a couple sheets of notebook paper to only show different sized sections, ignore the ruler in the picture while doin this.

Euclid,
Honing razors is not easy, but baking a cake isn't exactly a piece of pie either.

Michael

Here, here for bakers, there are bakers and there are… Bakers. True Baking really is much more art than science… even with a recipe. And maybe that makes my point. And you are right Michel, it’s not that easy, anything worth doing well rarely is.

All I’m saying is there is no recipe for much of this, because there are so many other variables. So there only guidelines. X worked for one person it might work for you and your stone. When we tell novices here is the recipe for honing a razor or lapping a stone we may be setting them up for failure because we don’t explain the variables, and we don’t know the largest - the pilot.

Back in the late 50’s Ben Hogan wrote, what at the time people thought was the definitive book on golf. To the dismay of many he wrote down all his secrets. It has sold multiple millions of copies. Why is it, there are only a handful of people in the world that can play golf at Tiger Woods’ level?

All of my finishers have scratches, Thüringen’s, Black & Translucent Arks, c12K and probably Coticlues & Synthetics as well they just don’t show as pronounced. All finish well, no fractured edges that I can see at 100 magnifications or feel shaving on my face. For me, that is what counts.

Lame you are right, if I could figure a way to even out the grit easily and retain the arc, it would make a good experiment, alas I am not that ambitious.

I always seem to have a change of heart when it comes to lapping/soaking/spritzing.

For past few weeks I've been going at 1k Chosera + 5/8/12 SS progression in dry-minimalistic style.
No water on any stones, and occasional lapping only on 1k when setting bevels, and
very light sandpapering with 1200 grit when the SS gets clogged up.
With the minimalist approach, though, I tend to move the razors around to wear the stones down evenly.

My current take is that the razors are as shave worthy as any, I save 10-15 minutes from stone preps, and hands stay dry.


I'm sure in 3 weeks I'll have a change of heart when I get frustrated from dished 8K and go into meticulous lapping/soaking routine for a while.

Originally Posted by Euclid440

Here, here for bakers, there are bakers and there are… Bakers. True Baking really is much more art than science… even with a recipe. And maybe that makes my point. And you are right Michel, it’s not that easy, anything worth doing well rarely is.

All I’m saying is there is no recipe for much of this, because there are so many other variables. So there only guidelines. X worked for one person it might work for you and your stone. When we tell novices here is the recipe for honing a razor or lapping a stone we may be setting them up for failure because we don’t explain the variables, and we don’t know the largest - the pilot.

Back in the late 50’s Ben Hogan wrote, what at the time people thought was the definitive book on golf. To the dismay of many he wrote down all his secrets. It has sold multiple millions of copies. Why is it, there are only a handful of people in the world that can play golf at Tiger Woods’ level?

All of my finishers have scratches, Thüringen’s, Black & Translucent Arks, c12K and probably Coticlues & Synthetics as well they just don’t show as pronounced. All finish well, no fractured edges that I can see at 100 magnifications or feel shaving on my face. For me, that is what counts.

Lame you are right, if I could figure a way to even out the grit easily and retain the arc, it would make a good experiment, alas I am not that ambitious.

__________________________________________________ _________________

Euclid,

You are on the ball. Keep posting.........................

Jerry