Thread: How does Lapping actually work?

Ok.... I understand that lapping makes the stone flatter- this part I get.

But..

How can you lap a 10,000 grit stone with a 250/400 grit sandpaper, and not have a bunch of scratches in it?

Oh... And should Nagura stones be lapped at the same time as hones? or does it not matter so much?

Peace Comrades...

I lap stones from 1K through 30K with nary a problem with a DMT 325. If there are scratches, they are not visible and don't affect honing results.

Originally Posted by CLaReNCe

Ok.... I understand that lapping makes the stone flatter- this part I get.

But..

How can you lap a 10,000 grit stone with a 250/400 grit sandpaper, and not have a bunch of scratches in it?

Oh... And should Nagura stones be lapped at the same time as hones? or does it not matter so much?

Peace Comrades...

It is not an issue for the function of most stones but if it concerns you you can use another flat stone to further polish.
Nagura & all stones should have lightly chamfered, smooth edges but the need for uber flatness of Nagura is debatable, after all it is usually softer than the base stone.
I remember seeing a recommendation to use the edge & not the flat for a particular slurry stone so in that case it would also be unnecessary to flatten.
If you mean a small 'truing' stone as supplied by some synthetic makers, it should be flat, as in that case it could be harder than the base stone.

Thanks Chaps...
Ps. Oz. My razor is still sharp as sharp- haven't wrecked it yet. Ta.

Hey guys
I just want to reignite this to throw an idea out there. When you lap a synthetic stone with a DMT 325, what do you think of the following idea. Any scratches don't matter because the bonding agent they use will be both dissolved and reinstated during the lapping process. This could be because you compress the material into the microscopic grooves made my the DMT 325. Also the slurry you make will round the edges of any grooves made on the surface. Just a thought, it doesn't really matter all that much but since gssixgun commented on a barber hone topic I have been thinking about it a lot.
What you think?

Carl.

I think when you are lapping with a DMT 325,after a very short time you are actually lapping with the slurry and not the diamonds.look at the scratch pattern on steel using a 325 under a scope,than look at the scratch pattern on the stone using the 325.

I will take a look this week!

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.