This is a three part series combining the use of an Atoma 140 for initial work on a VG10 Yanagi followed by the Nubatama Bamboo 150 grit stone to remove the 140 Atoma scratch pattern. In the third video I use the 150 Bamboo to restore a Carbon Steel santoku that has lost its edge to a thinned convex edge.
Here's the first video:
and the accompanying text:
In this first of three videos, I introduce the Nubatama 150 grit Bamboo series waterstone. In addition to the full sized stones, this stone is the first Nubatama stone available in the 1x6" aluminum backed size for the EdgePro. Expect more EP sized stones to follow in other grits, initially from the Bamboo series. All of these stones WILL have the official Nubatama stamps on them as a mark of authenticity and quality assurance.
This stone has been previously reviewed but no video was done at that time.
For this demonstration I will use a Shun Pro Yanagi made of solid VG-10, one of the more abrasion resistant steels I've ever encountered. Yes, VG10 being THAT abrasion resistant is a bit of an enigma. This particular knife is in rough shape with a very irregular front bevel. The initial factory grind on these has a large bevel on the back and front bevels, essentially creating a V grind, doubling the inclusive angle on a single bevel knife which has been partially corrected.
For the first part of this video series, I will start out using an Atoma 140 grit diamond lapping plate which is not new but well broken in to produce the initial scratch pattern. I will purposefully NOT abrade the knife to the point of burr generation but just to establish the 140 grit scratch pattern over most (not all) of the front bevel of the knife. In the second video (ran out of disk space) I will attempt (successfully) to remove this coarse scratch pattern using the 150 grit Nubatama Bamboo stone.
One of the reasons not to go all the way to burr formation with the diamond lapping plate is that these coarse diamond plates have a tendency to risk chipping out the edge of single bevel knives in particular with their narrow inclusive angle, so it is optimal to just 'get close' and then switch over to a waterstone scratch pattern of a similar grit.
Previous reports of the 150 Nubatama Bamboo on the EdgePro reports 'one of the fastest stones they have ever seen for burr formation' , leaving a finish slightly coarser than other 500 grit stones, cutting like the best of 150 grit stones, yet wearing quite slowly for a coarse grit stone as evidenced by the amount of mud produced during a sharpening procedure.
The Nubatama series of stones easily has the strongest lineup of coarse grit stones available, as well as the widest selection of mid grit stones, especially in the 1000 grit range.
The Atoma 140 is best used wet to maximize life of the nickel matrix holding the 'cookies on a cookie sheet' clusters of diamonds in place. This design results in minimized stiction or sticking to a stone when these plates are used for their alternative function of flattening waterstones.
As a point of technique, you should apply pressure very close to the edge rather than near the top of the bevel where it meets the flat area of the knife where the maker's signature is carved or embossed. This intersection is the Shinogi line and every effort must be made to maintain a precise crisp union of these two planes as a clean shinogi line. This is for both aesthetic reasons and to allow clean separation of slices of fish to separate from the knife during cutting.
New diamond plates are very aggressive and may give random extra coarse scratches, so it is best to use a broken in plate when abrading knife steel. There is one brief view of the Atoma 140 scratch pattern before the video ends abruptly, so be SURE to watch parts two and three of this introduction to the 150 grit Nubatama Bamboo.
The Atoma 140 grit diamond plate is available at Chefknivestogo:
In this second of three parts, I have already produced a scratch pattern with the Atoma 140 grit lapping plate on the front bevel of a Shun solid VG10 yanagi. Thee disk ran out of space so I continue here, but had already soaked the stone and begun abrading the knife with the 150 Nubatama Bamboo stone. We begin with an approximately 1/2 hour's delay with the stone still retaining water. The stone took approzimately 3 minutes to reach saturation. Now it is essentially immediately ready for use with just a splash of water.
I explain the difference between diamond and stone scratch patterns in the coarser grits, converting the scratch pattern.
Please not the absence of stone grit surrounding the stone. For a 150 grit stone this stone holds it's shape exceptionally well. Also not the absence of metal swarf buildup even when running the stone in a fairly dry - or wet state.
There is some burr formation produced using the 150 Bamboo Nubatama stone. I demonstrate burr removal techniques as well.
This is an exceptional low grit stone leaving an edge ready to go to a much finer stone, yet it is still quite aggressive and wears slowly for a coarse stone. Best of all worlds. This stone has been previously reviewed but no video was done at that time.
In this third of three videos utilizing the Nubatama Bamboo 150 grit Waterstone, in the previous two videos I put a coarse scratch pattern on a stainless steel (VG-10) Shun Yanagi with a 140 grit Atoma diamond lapping plate and removed it with the 150 Grit Bamboo stone quickly converting the coarser diamond scratch pattern where a burr was specifically not raised to a finer stone scratch pattern and raising an initial but purposely small burr, demonstrating how to easily remove the burr.
To demonstrate the versatility of the 150 Bamboo stone, in this video I will use it on a traditionally hand forged carbon steel knife (unknown origin).
While the knife looks 'shiny', over time it has lost it's edge as demonstrated by it's inability to cut through a rolled up paper towel. I will both thin the edge and reestablish an edge in this video.
I demonstrate thinning a convex edge, burr generation and removal, testing for a 'noticable increase in sharpness' prior to burr formation.
I conclude by testing cutting performance on a rolled up paper towel, demonstrating very good cutting performance even letting the paper get cut supporting the weight of the knife.
This is a stone that is pretty much a 'must have' stone for any serious knife sharpener, showing excellent performance for both carbon and stainless steel knives.
I don't have any scratch pattern pics separate from the video at this time. Look at 6:18 on the first video for the Atoma 140 and 2:47 on the second video for the 150 Nubatama. The first video ended prematurely so I didn't have the chance to catch the coarse scratchpattern of the 140 Atoma too well. The 140 scratches are best seen in the mid section area of the uneven bevel.