Forever Diamond Titanium knives

[kwakster]

*** This review was posted earlier on several international knife forums ***

In the past i did 2 reviews on different Forever kitchen knives, 1 x ceramic, and 1 x titanium hybrid, both for myself and forum members to enjoy on various international knife forums.
A few weeks ago i decided to send the links to those reviews to Forever head quarters in Japan to see if i would get a reaction or not.
To my surprise i was contacted a few days later by a friendly Englishman, who told me that they had read my reviews with interest and we got to talk a bit about their products.

Well, to make a long story even longer he offered to send me several Forever knives as samples and told me that i could use any of them how i'd think best, and that he hoped this would be somehow beneficial for them as a company (Forever is still a virtual unknown in the Netherlands and no shops carry their knives.)

Just before my holiday i received the package, and in it were several Diamond Titanium knives (as well as some ceramic cutlery items, but this thread is solely about the Diamond Titanium models)

These pics i've taken from the internet:

 

[kwakster]

These are the Diamond Titanium knives i received, minus one Chef knife which i already sent through to one of the admins of British knife forum Edgematters.uk, to use as he thinks best.
Soon one of the remaining new models is going to be used for a while by a professional sous-Chef in a busy restaurant kitchen, and his report will be written down later on in this thread.



One santoku is already in use in our own kitchen & i use it for sharpening practice.
The text on the blade is already fading due to handling, but to me that doesn't matter.



The still new & unused Santoku model:



Specs:

Overall length: 32,1 cm (12.64 inch)
Blade length: 18,7 cm (7.36 inch)
Blade thickness: 1,51 mm
Blade material: titanium alloy (48 HRC) with diamond particles, ceramic particles, and silver.
Handle material: Plastic
Weight: 84 grams

The still new & unused Chef knife:



Specs:

Overall length: 35,0 cm (13.78 inch)
Blade length: 21,5 cm (8.46 inch)
Blade thickness: 1,78 mm
Blade material: titanium alloy (48 HRC) with diamond particles, ceramic particles, and silver.
Handle material: Plastic
Weight: 94 grams

 

[kwakster]

The performance in our home kitchen so far is quite positive i would say, and things that stand out for me are the ultra low weight and the aggressiveness of the factory cutting edge, even though that edge is only copy paper slicing sharp.
Since one of these knives is going to be tested for some time by a real Chef who is used to truly sharp steel knives (which i sharpen for him) i want to find out if i can improve upon the factory sharpness of this material.

 

[kwakster]

The factory edge on the knife was only copy paper slicing sharp, and when i looked at the apex through my Victorinox loupe i could see that it was more or less micro-serrated over it's entire length (due to it being rather coarsely sharpened at the factory)
Trying to improve upon the sharpness (in my case with Paper Wheels coated with various diamond compounds) turned out to be possible, and after 15, 6, and 3 micron those micro-serrations disappeared and the apex became clean and fine enough to shave the hair from the back of my hand at an inclusive edge angle of between 25 and 30 degrees.
Even though motorized the process was very time consuming, and with each finer diamond compound things slowed down even more.

All the work turned out pretty useless in the end: after using the knife just one time on a good wooden cutting board to cut up all the ingredients for a big pasta salad (various onions, bell peppers, garlic & broccoli) the apex sustained damage in some places (seen through the loupe), and i think i saw both microchipping & rolling (not sure)
My guess is that just like it's Cera-Titan counterpart the Dia-Titan alloy & high sharpness polished edges don't go together well, and it probably does better and longer with a less refined edge.
Removing the damage and resharpening to factory sharpness however was quite easily done with a DMT Diafold Fine/Red, and afterwards i did a little cardboard cutting test.

With the new & less refined edge the knife sliced a measured 100 meters or 328 feet of double walled cardboard plus 70 meters or 229 feet of single walled cardboard without tearing, and at that point i ran out of cardboard.
Afterwards when seen through my loupe the edge showed no damage other than a very narrow line of light over it's entire length, and i'm convinced it could have sliced a whole lot more cardboard.
The edge is also still sharp enough to slice copypaper.



I will now resharpen the edge with just the DMT Diafold Fine/Red and continue to use it in our kitchen.

 

[kwakster]

Besides being 100 % rust proof and the edges having a very high wear resistance the blade material also has active anti-bacterial properties due to silver particles in the alloys of both the Diamond Titanium & the Cera Titanium line.

Japan Food Research Laboratories did a test where E-Coli bacteria were put on different blade materials, and then microscopic pictures were taken at various time intervals to see what happened.
I found the pic below on a German website.
The first row shows a Forever titanium blade, and the second row shows a stainless steel one.



Japan Food Research Laboratories

 

[kwakster]

At this point in time and after just a short period of testing i would say that the edge is quite durable.
Not so much in keeping a super high sharpness , think hairwhittling / treetopping / arm hair shaving (although i plan to experiment further with various other sharpening methods), but the material surely seems to be able to hold a good useable edge for actual kitchen use.
Although titanium at 48 HRC isn't very hard itself, in these blades it acts as the matrix to hold the diamond & ceramic particles, which are responsible for the very high wear resistance, and i think that together with the other alloying ingredients this provides for enough firmness for the edge apex so that it doesn't fold over or chips easily in actual use.
So far i haven't seen it anyway.

Now at the moment i'm experimenting with regrinding the blade as the factory grind was a bit too thick for my taste, plus i wanted to see if it was at all possible.
The factory edge measured somewhere between 25 and 30 degrees inclusive, with a thickness behind the edge of 0,54 mm.
Now the blade is a very shallow convex with something that resembles a zero edge, and the new apex fits in the 20 degrees inclusive slot of my Tormek WM 200 Angle Master.
Besides the fact that the knife now cuts in an entire different league the edge so far seems to hold up in both my kitchen use as well as in cutting quite a bit of cardboard without it folding over or chipping.

 

[kwakster]

Today sous-Chef Patrick sent me his impressions on the factory fresh Diamond Titanium santoku knife that i lent him to use, the still new & unused Santoku model:



Below is what he wrote me (translated from Dutch):

"You asked me to write down my experiences with the new Diamond Titanium Santoku knife.
Well, i used the knife exclusively for 15-20 hours mostly on vegetables, and here is a list:

5 kilogram of tomatoes
1.5 kilogram of string beans
5 kilogram of white onions
1.5 kilogram of legumes (very thin)
8 large cabbages
15 kilogram of paprika's
5 kilogram of Bouquet garni (carrot, onion, leek, celeriac)
plus about 2 kilograms of other vegetables

Further for

portioning meat
cleaning fish
removing ends of various vegetables
etc.

Plus:

The knife is thin, so there is less resistance to cut through something.
After cutting all of the above i notice little to no loss of sharpness.
Lightweight, which is quite pleasant if you have to use the knife multiple hours straight during the day.
Completely rust proof.

Minus:

The knife is not sharp enough for some jobs, like cutting up chive.
The knife is absolutely unsuitable for pushcuts (i found out that unconciously i do a lot of pushcutting)
On harder vegetables i need to exert more pressure due to which i get the impression that the knife starts to wander".

Patrick already returned the knife to me, and in exchange i lent him the other santoku that i reground to a shallow convex with an edge angle of 20 degrees inclusive and an apex finished with a DMT Diafold Fine/Red coated with some WD40.

His first impressions with the reground version:

" I've already used the reground knife intensively for 2 days straight, and for about the same jobs as i described earlier, which will make good comparison later.
I notice that this knife cuts a lot better, it's also possible to pushcut with, it wanders much less, and it seems sharper (or really is sharper)"

More to follow later,

 

[kwakster]

On the 15th of November i received this e-mail from Patrick (translated from Dutch):

"I didn't keep track of how much exactly i used the diamond titanium knife during the past two months, but my best guess is that i used both my own santoku (a Sakai Takayuki in cladded VG10 steel) and your knife about equally as much.

I did touch up my own knife from time to time on a ceramic rod, while i did nothing to your knife.

Could i visit you somewhere next week to show you the results ?
Your knife is clearly still much sharper than my santoku, which will now only get temporarily sharp if i touch it up on the ceramic rod again."

 

[kwakster]

A few days ago Chef Patrick brought me the two knives, and this morning he came by to collect his own knife again.
These first two pics show Patrick's own Sakai Takayuki santoku in cladded VG10 steel together with the reground diamond titanium santoku.
Patricks knife has already been resharpened again in the pics since he needed it back asap, as it is his main workhorse (bought new over 5 years ago)
I've sharpened this knife many times already and find the VG10 very well heat treated, imo comparable to Tojiro's.
All pics show the Diamond Titanium knife just as i received it from Patrick, only cleaned with a soft toothbrush and some mild detergent, but not resharpened yet.



The Diamond Titanium knife does indeed still cut better than Patrick's Sakai Takayuki, but that is mostly because of the thinner blade coupled with the thinner edge angle (20 degrees inclusive versus 25 degrees inclusive)
Where the used edge on the Sakai Takayuki was nearly worn smooth, the used edge on the diamond titanium blade has become coarser and it's apex has widened.
The remaining sharpness is such that with a little effort it will still slice a piece of copy paper, but it snags a bit here and there on a few microchips (these are visible in the pics).
Patrick's santoku could not slice the same copy paper, no matter how i tried.
When seen through my Victorinox loupe using daylight the entire apex of the diamond titanium knife looks a bit rough, and this has the effect of micro or even nano serrations.
Thickness behind the current edge (measured about a millimeter behind the actual apex) hovers between 0.25 and 0.3 mm.
Tomorrow i hope to test the knife myself on a few tomato's, just to see if the edge will still cut these or not.
For Patrick anyway the current sharpness is no longer sufficient for his kitchen use.

(Pics can be clicked 2 X for more detail)







A few more up-close shots:
(Pics can be clicked 2 X for more detail)









What surprised both myself as well as Patrick the most is that the knife held up so well with it's reground blade and it's low edge angle of just 20 degrees inclusive, the very apex of which had been sharpened on a DMT Red (about 750 grit) with a bit of WD40 as a lubricant.
Patrick said that he estimated the amount of food that he had cut with the knife during those two months would be comparable to what a standard family could eat in more than a year (easily).
He also told me that he didn't use the knife on hard pumpkins because he was afraid that he might damage the thin blade, but for the rest used it on everything, just like his own knife.

During the time that Patrick had the knife i found that the manufacturer recommended diamond sharpening device has a grit rating of 1200, so in the mean time i've bough 3 cheap Chinese diamond plates on the Bay in grits 1200, 2000, and 3000, and on the second (also reground) Diamond Titanium santoku that i use in our home kitchen the apex is only sharpened with the 3000 grit diamond plate.

To be continued.

 

[kwakster]

The knife that Chef Patrick used for two months in a commercial kitchen could still slice a firm tomato in good standard slices (not paper thin ones) with very light pressure, and i think that many non-knife people would have still considered it sharp enough.

I chose to resharpen the edge freehand using a few cheap Chinese diamond plates that i got from the Bay for under 10 Euro's (about 12 US dollars) including shipping costs from China to the Netherlands.

Grit 1200 / 2000 / 3000, each one measuring 17 cm x 7.5 cm x 0.99 mm



I found that using just the 3000 grit diamond plate would have taken too long to get the microchips out, so i exchanged it for the 2000 grit plate for the majority of the work and then refined the edge with the 3000 grit plate.
Total sharpening time was about half an hour to 40 minutes, but i took my time, used light strokes, and washed the plates in between with some detergent & an old soft toothbrush.

So far i haven't noticed that sharpening the blade edge leading using just these 2 fine diamond plates produces any kind of burr (or it's just too small to notice it), like it did when i reground the blade on 240 and 400 grit SiC wet & dry and WD40 as a lubricant.
The new edge can slice-shave the hair on the back of my hand fairly well, and the edge angle has increased from 20 degrees inclusive to between 22.5 and 25 degrees inclusive with a small, but visible bevel.
The knife will now be put away until Patrick drops by again.

NB: the edge of the Diamond Titanium knife produced visible scratches on both the grit 2000 and the grit 3000 diamond plates during sharpening.
These scratches are very superficial, but they are definitely there to stay.

 

[kwakster]

Update:

I asked Patrick who tested the knife in a commercial kitchen a while ago if he would ever consider buying one of these diamond titanium knives for the retail price they cost, and his answer was no.
His two reasons: in hindsight he found the blade a bit too flexible for his specific uses, plus the knife didn't look anywhere near as good as it performed (after the regrind)
He said the knife just looked cheap, a remark i heard from several people.

If he as a professional Chef were to consider such a diamond titanium knife it would need to have:

- A little more rigid blade.
- A full flat ground blade which would have to be ground noticeably thinner behind the edge, or maybe even have a shallow full convex shape. (more like the reground blade)
- A bit more upscale handle (maybe a traditional wa-shape, be it in real wood or good quality plastic)
- A nice quality box in which the knife would be protected and could be transported safely.
- If possible come complete with a means of maintaining the edge in the kitchen (like for instance a diamond plate)

Patrick thinks that the diamond titanium material might also work well in filleting knives, to which i would like to add fixed diving blades and maybe even folders (with titanium or Zytel handles).
Possible other uses might include specialized knives for cutting various comparatively soft but abrasive materials like cardboard or insulation materials.

The hand-reground santoku that the Chef tested is now in home use with my parents in law, both in their 70's and completely non-knife oriented people.
They are very happy with the knife, praising both it's lightness and it's thinness/cutting ability, and they have even used it several times to cut up larger pumpkins for soup with no ill effects on the blade or edge that i could see.
The knife is used in their home kitchen literally every day, and i've not resharpened it since i gave it to them over a year ago.

It's twin brother (also hand-reground) is in use almost every day in our home kitchen.
For some time now i only use the 2000 grit diamond plate for a touch-up, but this is rarely needed.
Current edge angle measures between 20 and 22.5 degrees inclusive, and the thickness behind the tiny bevel measures around 0.2-0.25 mm.
The knife weighs 83.4 grams, has a toothy edge that never wears smooth, and continues to be a joy to use.