Thread: Lapping / Slurry stone question not covered in the Wiki

I've recently lapped 2 Charnley Forests by placing a $3 diamond hone with plastic backing on a glassplate. I'm sure it's slower than with a DMT but it's much cheaper. Afterwards you will have to lap it on 120 or 240 sanding paper but that shouldn't take long.

Originally Posted by Piet

I've recently lapped 2 Charnley Forests by placing a $3 diamond hone with plastic backing on a glassplate. I'm sure it's slower than with a DMT but it's much cheaper. Afterwards you will have to lap it on 120 or 240 sanding paper but that shouldn't take long.

It was an 80 grit plate? It must have been very uneven to require that low a grit.

It seems as though hones really are treated like pieces of wood. First you look for visible signs of uneven surfaces, and then find anything you can to start flattening, smoothing and polishing it. I learn something every day.

When is it appropriate to end the lapping process? Must a fine stone like the CF be lapped up to a certain grit? Like 1200? or higher? No one seems to lap it up to 16k, but no one seems to stop at 325. Is there a technical reason for choosing a certain grit, or must it only be flat?

Other than lapping a Coti on 600 paper, I've no experience doing this, but I've recently acquired a few stones (five or six, as it turns out) and really need to lap them all. Some of them will be difficult, like the Aloxite BH that actually feels rough, and the CF, which probably needs it. perhaps I really do need to bite the bullet and pick up an 8" 325 DMT just to get through all these crazy hones.

I've never been able to figure out why a stone lapped to 325 is capable of honing at higher levels.

HAD; I'm beggin' ya.

I lapped my CF on a 325 DMT and it worked great. CF's are really hard stones (way harder than a coticule) and I have to agree with Sham that you'll chew through a lot of paper getting it lapped!

But that 325 leaves a nice flat smooth surface and I didnt need to do anything else after that. Just the 325 and it was ready to go.

I dont use mine with slurry either. I was lucky and mine hasnt been used with oil, so I use a tip that JimmyHAD gave me: Put a couple of drops of dish soap on the hone before you start honing and that gives you the same result as oil, with the added advantage that you can wash it off!

After I come off the 12k Naniwa, I put some soap on the CF and then do 40 or 50 laps on the stone. Then I just go right to my daily strop and test shave, I dont use any pastes at all.

I gotta say, between them my CF and Maruichi have pretty much rendered my pasted strops redundant!

Originally Posted by MarkinLondon

It was an 80 grit plate? It must have been very uneven to require that low a grit.

The glass plate I used is just standard glass I took out of a container

I place the $3 diamond hone on the glass to keep it flat. I noticed when using it in hand it bends a little.

Mark in London,

I've been using the Atoma #400 diamond plates for about 4 years now and found them to be a good value at about $125 for a 8 1/4 x 3 inch size. The electroplated nickle process to fix the diamonds is excellent and I have no indication of ever having lost a diamond and I have never had a diamond chip show up in the slurry of any of my sharpening sessions. The diamonds do however, as with any diamond plate, gradually soften their action so that over time the 400 plate begins to feel like a 600 or 800 action. This is not all that bad though because when a plate softens like that I reserve it for my more expensive and rare stones where I desire to minimize the lapping action.

One thing about doing a serious resurface job on a stone is that the amount of stone material you eventually remove has to itself be removed from the lapping surface matrix in order to progress with speed. This stone swarf clogs the lapper and unless you can rinse it out the speed is greatly slowed down. A diamond plate, Shapton or Atoma is great because it can be imersed and rinsed off in a bucket of water with a bursh and once done it regains 100% of its lapping strength. The backing I have found of sand paper including wet/dry emory or garnet or whatever does eventully loose its ability to hold the grit, so not only does the grit loose its sharp cutting edges but the grit also falls off the paper.

About using your Charnley as a water stone after it was used as an oil stone, if you are going to lap the CF you may get below the oil stained areas faster than you think, and once you do you might just try using it as a water stone. I have done this with Arkansas's that had been oil stones and they will perform excellent with water and a light slurry created with a DN (diamond nagura). Alx

If you want to use your CF stone with slurry, but you do not want to use diamond plates, why not saw a little piece from your CF and use it as a slurry stone. Laugh if i'm wrong: i do not know anything about CF stones, rather this was just me thinking aloud

$125 for a lapping plate! That's too rich for my blood. I havent picked up the DMT because it's £55!

But.... it seems like I've got a lot of lapping to do. I've got an Aloxite barber hone that needs help, a Charnley on the way, and next month a Dragon's Tongue will be delivered. I've also got an ancient Tam O'Shanter that's nowhere near flat.

I did see a heavy (14lbs) Norton cast iron lapping plate that has deep figure-eight grooves cut into it. It's only about £20. No one uses that, right?

I'm going to end up dropping the 50 quid on an 8x3 DMT plate, aren't I?

Yep!

Seriously, that 325 DMT is a great investment and not just for lapping. You can also use it for razors that have chips or need any other major bevel work doing.

When you get that eBay razor with a chip in the edge you'll be glad of that DMT..! You'll have the chip out in short order and all your hones will be lapped flatter than a flat thing.

I wouldnt recommend spending the money if you didnt need it, but I really do think that a 325 DMT is one of those stones thats worth its weight in gold.

There is in fact a non-synthetic Slurry-Stone (aka. Nagura) solution,
besides (obviously) using a similar or identical stone to create mud.

I recently purchased a Tsushima Black Nagura.
It is a black chunk that is used to create mud.
Rumors say it is mined under the sea... IDK

Japanische Schleifsteine für Küchen- und Rasiermesser ::

Anyhow, this stone creates mud perfectly AND I have not ever noticed
any sideffects. And you guys know I am picky with scratches etc.

I use this nagura on my Naniwa Super 10k and get a perfect mirror
instantly (I mean 40x-100x mag. perfection).
I use it on my nakayama or ohira and get the hazy finish they usually provide.

I don´t know why, but it works.
It´s expensive, though.

Besides this I use a DMT card in fine.
Handy, creates slurry on anything... what more could you ask for?


The problem with every slurry creating action with a stone
considerably smaller than the CF: you will get uneven wear.
This means you will have to lap it more often,
but it doesn´t mean you have to lap it much, anyway.
Instead of every 100 razors, maybe every 50 now...