Flattening naturals

[Nick112]

Hi
I read some ppl say there are little need or no need to flatten naturals, but at the same time, an absolute flat stone is important. So if I receieve a new natural, should I flatten it? I have an atoma 600 that I use on my 1000-8000 synths. Can a 600 grit atoma scratch a very very smooth natural with scratches or? Nakayama or ohira suita. Any valueable input what to think about when flattening naturals?

thanks

 

[valgard]

Absolutely, flatten your stones!

You can prepare the surface after flattening with finer plates but for actually flattening I highly recommend you get an atoma 140.
I have all sorts of jnats, I flatten with an Atoma 140. For creating slurry I use either a worn atoma 140 or a small atoma 400. For harder stones I might use the atoma 1200 to prepare the surface. But for actual flattening (you need it more with softer stones) us the 140 always.

 

[valgard]

When I want the finest possible result for a stone I simply polish the surface with progressively finer stones after flattening, finishing with a nagura, then rinse the stone and proceed to use it. But except for razors or trying to get an ultra fine polish this is hardly ever a concern. In fact, having a rougher surface helps with releasing abrasive, and thus, with speed.

 

[Nick112]

When using diamond plates as atoma, there are no risk or issues with any (coarser) particles coming from the plate contaminating the natural stone and get stuck in the stone? that wont clean up by rinsing the stone

 

[kayman67]

Only when new. Not that much later on.

Best and easiest way to keep them flat so far, was using SiC abrasive powders and a metal sheet (some cookie or pizza or whatever similar metal tray works fine and keeps everything under control). The Atoma would be just to keep them clean if necessary and making slurry.

 

[Nick112]

How do you recommend making sure it is as flat as it can be? Since flatness is important. Do you use a pencil to draw lines and then use a large atoma plate to flatten ”away” all the marks? Or do any of you use a straightedge or something to measure or verify the degree of flatness?

 

[ian]

Use the pencil trick, that’s all you’ll ever need. With a straight edge you’d have to remeasure every couple seconds while flattening. Not fun.

 

[nutmeg]

How do you recommend making sure it is as flat as it can be? Since flatness is important. Do you use a pencil to draw lines and then use a large atoma plate to flatten ”away” all the marks? Or do any of you use a straightedge or something to measure or verify the degree of flatness?

you‘ll see when the stone becomes flat, no need to draw lines or anything.
But 600 is too fine. You must do it under running water but it will be a huge amount of water with 600! 100-200 is better for flattening.
I wouldn‘t care about scratches on 600, even on a very hard stone.
On a soft suita I don‘t care about any scratches, big holes or cracks on the stone surface.

 

[ian]

you‘ll see when the stone us flat, no nee to draw lines or anything.
But 600 is too fine IMO. You must do it under running water but it will be a hige amount of water with 600!
I wouldn‘t care about scratches on 600, even on a very hard stone.
On a soft suita I don‘t care about any scratches, holes or cracks on the stone surface.

You’re definitely the master here, but on a soft stone with a lot of slurry it can be a little difficult to detect where the flattening plate is actually flattening, and where it’s pushing around slurry. For a master, I’m sure it’s easy to tell, but for the person asking the question the pencil trick takes all the guess work out of it. And then if you start to think you can do without it, more power to you.

Note also that even if the stone is already flat, you’re not going to abrade much off is testing for flatness with the pencil trick, since it’s come off immediately and uniformly.

 

[nutmeg]

You’re definitely the master here, but on a soft stone with a lot of slurry it can be a little difficult to detect where the flattening plate is actually flattening, and where it’s pushing around slurry. For a master, I’m sure it’s easy to tell, but for the person asking the question the pencil trick takes all the guess work out of it. And then if you start to think you can do without it, more power to you.

Note also that even if the stone is already flat, you’re not going to abrade much off is testing for flatness with the pencil trick, since it’s come off immediately and uniformly.

thanks for the flowers..!

I always flatten stones under running water. This makes things go 2-5 times faster.
Under running water you don‘t have any slurry so you can see the surface clearly.
If you use your diamond plate only in one direction you‘ll see the scratch pattern and a brighter surface. Where there is no scratches, the diamond plate hasn‘t been there. Once the color is uniform, the stone is flatter than any knife ;-)

 

[nutmeg]

But always use the diamond plate parallel to the length of the stone.
Perpendicular is much faster but the stone will never be flat.
And use PRESSURE. 20kg or so. The more you can. The stone won‘t never break.

 

[Alder26]

Super useful information I had never considered most of these techniques!

 

[4wa1l]

A big bump but seems like a good place to ask.

I have read that the very coarse grooved flattening stones shouldn't be used on natural stones because of contamination issues. How solidly can a stray coarse particle be embedded, especially if you use a finer synthetic to smooth out the surface after the bulk of the flattening work?

I keep my synthetics flat by using one of these flattening stones as well as using the stones on each other so that everything actually stays flat (Like the 3 stone method).

The reason for the question is that I have a new natural koppa and it is not very flat. Can I flatten using my current method or is an atoma 140 the only way?

 

[inferno]

i flatten all the time with a 100 grit SiC stone (non slotted). its my go to flattener right now. its cheap and it just works. its completely useless for sharpening though. i have noticed that you need to clean the stone better than just splashing some water on it after flattening. but rubbing any other stone on the newly flattened stone will work.

for the initial flattening of nats i suggest going with loose grit SiC on glass. its about 10 times faster than any other method. nats can be surprisingly slow to flatten on plates. like 30 minutes on coarse diamonds.

 

[4wa1l]

Thanks for the response! Unfortunately I don't really have the space for a glass plate so I would prefer to avoid that method. I will probably get a diamond plate at some stage but in the meantime this one should be sufficient even if it takes a long time? It's 100 grit but no idea if it's SiC?

https://www.suehiro-toishi.com/en/syusei/ss-1/

 

[inferno]

its black SiC!

you wiill need to flatten this too sooner or later with sic powder and glass.

 

[4wa1l]

If I use it as part of the 3 stone process should I be able to maintain flatness without having to flatten it? Seems like it's working so far but I haven't had to do a lot of flattening yet and do a little frequently rather than big flattening sessions sporadically.

I appreciate the help. Always so much to learn : )

 

[4wa1l]

nats can be surprisingly slow to flatten on plates.

You weren't kidding. Just gave it a go with the SiC flattener. I thought my chosera was bad enough to flatten but these were something else. Both stones are flat in the centre but still some low spots in the corners which I'm not too worried about. I figure they'd wear slower there anyway.

 

[inferno]

you can put sic powder between the flattener and the nat to speed things up. just flip it upside down and work on the flat surface.
its the last few % that takes time to flatten!

 

[psfred]

Rolling grit works much faster than a diamond plate. Use light pressure, you don't want to crush the grit, you want it to roll around and dig bits out of the stone.

Rate of removal slows way down as you approach flat, sadly, and indeed that last few percent comes off much slower than at the beginning.

 

[spaceconvoy]

Whenever I suggest the Atoma 400 I get overruled by fans of the 140, but I still think they're wrong To be fair, I've never tried the Atoma 140, and have only compared my 400 to a JKI 150 diamond plate. Please let me know if you think the Atoma is significantly different from JKI to warrant revaluation. But here's my general rationale for preferring a finer flattening plate:

If you don't flatten after every use, then a coarser plate is probably better. But I think that's bad practice, similar to not thinning knives every session. In both cases you're just kicking the can down the road, increasing your future workload and creating the need for coarser stones/plates. You can get away with a smaller kit if you're willing to put in the work every time. Your results will be more consistent and you'll be less likely to make big mistakes or remove too much material.

If you do flatten after every use, then the Atoma 400 is ideal. The slowness and suction that people complain about are actually great strengths if your main concern is removing as little material as possible. I don't bother marking Xs or checking flatness visually, I just go by feel. Once the plate slows down and starts to stick to the stone, its flat. I do this under running water and don't have problems separating them. It's not too slow if you flatten every time, each stone takes less than a minute.

Coarse diamond plates remove too much stone for my taste, and I don't like how the JKI 150 just keeps removing material without much resistance. You have to really pay attention if you only want to remove the bare minimum to achieve flatness (maybe the crisscross channels are the culprit and Atoma 140 isn't like this?) It's great for flattening a super dished stone, but overkill if you don't let your stones get super dished.

Not only do coarse plates remove more material during flattening, but also lead to more dishing during sharpening. The coarser surface texture has more dramatic peaks and valleys, and releases more mud than a finer surface would. It might be subtle but it adds up, especially for naturals if you're hoping to get a lifetime of use out of them.

/rant