Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?
--
Chris

Chris ] wrote in ]:

Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?

You regularly buy new ones?

--
Rod

www.annalaurie.co.uk

On Tue, 25 Jan 2005 22:05:38 +0000, Chris ] wrote:

Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?

We bought one of those 'Kitchen Devil' general purpose kitchen knives
quite a few years ago and recently (whilst I was hacking up some big
root veg for a stew) had the blade break out of the handle.

Because it was so handy I went out and bought another (£2.99 or
summat) and noted on the package that it was 'guaranteed for life'.

I stuck the broken knife in the new knife's packaging (to make it safe
in the post) and returned it with (an honest) covering note.

I got a new replacement a few days later with a note apologizing for
"the failure of the product", but added that "the model was *last*
produced over 12 years ago!" ;-)

All the best ..

T i m

"Chris" ] wrote in message
]...
Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?
--
Chris

Probably Titanium coated knife edges, they will stay reasonably sharp for a
long time but when they eventualy go dull you will not be able to sharpen
them.

Kaiser wrote:

"Chris" ] wrote in message
]...
Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?

Probably Titanium coated knife edges, they will stay reasonably sharp for a
long time but when they eventualy go dull you will not be able to sharpen
them.

Titanium Nitride is a golden colour, and forms a wear resistant and fairly
slippery coating.
You can sharpen, but you're then back to the base metal.

Titanium (metal) doesn't make good knives, and is only used in very unusual
circumstances - diving knives, where its seawater resistance is needed, for
example.

Titanium (metal) coating is never (?) used on cutting tools, as titanium
isn't really any good for that.


They may be saw-edged ones, which though they will cut and go on cutting
things for a longer time than a straight blade, will not produce as clean
a cut.
You can't just chop with them (when slightly blunt) but need to saw.

"Chris" ] wrote in message
]...
Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?
--

If the guarantee says so, then keep them to it! But no, there is no such
thing as a knife that never needs sharpening. Steel this hard is extremely
difficult to get a good edge on, but will keep the edge for a long time
(assuming you don't cut onto metal, glass or ceramic - wood/plastic only if
you care about your knife!). When the edge goes, it's again very hard to
sharpen (and isn't really possible in practical terms).

I find this type of knife (Kitchen Devils are a good example) are nice and
cheap and good for everyday slicing & dicing. I sharpen them as best I can
with a ceramic sharpener maybe 2/3 times a year and it keeps them good for
rough chopping veg and slicing up meat.

However, expensive knives are a beautiful treat after them and a must for
fine chopping or carving (or filleting if you do it). Real easy to sharpen
with some good wetstones and bring a scary sharp edge to, but need far more
TLC to keep good!


Hope this helps - if you can't be bothered caring for knives, buy the
stainless, hard, cheap ones and replace every year or so (or send them back
blunt and see what happens!). If you can be bothered, spend the extra money
for a couple of really good knives, care for them well and enter a new world
of cutting things translucently thin!!



a

On Tue, 25 Jan 2005 22:05:38 +0000, Chris ] wrote:

Just seen some knives in Tesco that allegedly never need sharpening!

Yes, been around about 20 years now.

Personally I'd rather have knives that were really sharp in the first
place - buy some Globals.

"Ian Stirling" wrote in message
...
Kaiser wrote:

"Chris" ] wrote in message
]...
Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?

Probably Titanium coated knife edges, they will stay reasonably sharp for
a
long time but when they eventualy go dull you will not be able to sharpen
them.

Titanium Nitride is a golden colour, and forms a wear resistant and fairly
slippery coating.
You can sharpen, but you're then back to the base metal.


I was under the impression that these cannot be sharpened with a steel or a
conventional knife sharpener, but only with a green grit wheel or diamond
file ect.?

Kaiser wrote:

"Ian Stirling" wrote in message
...
Kaiser wrote:

"Chris" ] wrote in message
]...
Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?

Probably Titanium coated knife edges, they will stay reasonably sharp for
a
long time but when they eventualy go dull you will not be able to sharpen
them.

Titanium Nitride is a golden colour, and forms a wear resistant and fairly
slippery coating.
You can sharpen, but you're then back to the base metal.

I was under the impression that these cannot be sharpened with a steel or a
conventional knife sharpener, but only with a green grit wheel or diamond
file ect.?

Once you wear off the coating (however it's done), you are just back to the
underlying metal.

"al" wrote in message
...
"Chris" ] wrote in message
]...
Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?
--

If the guarantee says so, then keep them to it! But no, there is no such
thing as a knife that never needs sharpening. Steel this hard is
extremely
difficult to get a good edge on, but will keep the edge for a long time
(assuming you don't cut onto metal, glass or ceramic - wood/plastic only
if
you care about your knife!). When the edge goes, it's again very hard to
sharpen (and isn't really possible in practical terms).

I find this type of knife (Kitchen Devils are a good example) are nice and
cheap and good for everyday slicing & dicing. I sharpen them as best I
can
with a ceramic sharpener maybe 2/3 times a year and it keeps them good for
rough chopping veg and slicing up meat.

I've had an inexpens .. no, let's be honest, 'cheap' (!) Prestige
carving/bread "never needs sharpening" knife with a scalloped edge for 30
years or more, and even though it's cheap hard metal, I can still get a good
edge on it with a sharpening steel. Mind you, it's not as 'scalloped' as it
used to be .. ;o)

Ian Stirling wrote:

They may be saw-edged ones, which though they will cut and go on cutting
things for a longer time than a straight blade, will not produce as clean
a cut.
You can't just chop with them (when slightly blunt) but need to saw.

"Laseredge" (IIRC) are like this. I had one that served as a good all
round knife for a few years, and still sometimes gets used as a steak
knife. Not as sharp as it used to be though.

--
Spamtrap in use
To email replace 127.0.0.1 with blueyonder dot co dot uk

"Mike Faithfull" wrote in message
news:41f7dbe5$0$19155$cc9e4d1f@news-
I've had an inexpens .. no, let's be honest, 'cheap' (!) Prestige
carving/bread "never needs sharpening" knife with a scalloped edge for 30
years or more, and even though it's cheap hard metal, I can still get a
good
edge on it with a sharpening steel. Mind you, it's not as 'scalloped' as
it
used to be .. ;o)


Cheap and soft blades are easy to sharpen, but never get *really* sharp and
loose their edge too quickly. However, you can still sharpen them far
better than most people know knives are meant to be so by all means go this
route.

If you get a chance though, check out a knife shop (please not some crappy
up-market department store with morons for staff!) and get a demo of a
really good knife. Over about £40 generally for a good size chef's or
carver.

I like Japanese knives personally and have a beautiful Damascus steel carver
and chef's knife. About £80 each. I also have a collection of other
reasonable knives (£100 set) to cover all other eventualities and everyday
use.



a

"Andy Dingley" wrote in message
...
Personally I'd rather have knives that were really sharp in the first
place - buy some Globals.

Globals are great, great knives. I just prefer the feel of wooden handles
ones. Always try before you buy to make sure you like the weight, balance
and feel.




a

Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?

Don't know, but we just got an Ice Bear ceramic zirconium knife from
Axminster. Apparently it's only posible to sharpen it with a diamond
whetstone - if it ever needs it. This thing is so sharp it's scary.
Dave

"Dave" wrote in message
oups.com...
Don't know, but we just got an Ice Bear ceramic zirconium knife from
Axminster. Apparently it's only posible to sharpen it with a diamond
whetstone - if it ever needs it. This thing is so sharp it's scary.
Dave

It's quite a simple equation when it comes to sharpening really. The
material you sharpen with has to be harder than the blade you're sharpening.
Otherwise it can't grind away the metal/ceramic.

You can quite easily buy sharpeners for ceramic and other hard blades (just
because the word "diamond" is mentioned, doesn't mean Pussy Galore's about
to come marching in!!). However, hard blades will never hold a good edge as
you just can't sharpen it like a good workable metal blade.




a

"al" wrote in message
k...

If you get a chance though, check out a knife shop (please not some crappy
up-market department store with morons for staff!) and get a demo of a
really good knife. Over about £40 generally for a good size chef's or
carver.

I like Japanese knives personally and have a beautiful Damascus steel
carver
and chef's knife. About £80 each. I also have a collection of other
reasonable knives (£100 set) to cover all other eventualities and everyday
use.

I would dearly love to own and use some good quality knives, but I'm afraid
'The Management' lacks a certain empathy with such things and I'm sure she
would all too quickly damage either them or herself ...

Like she says "I look after your shirts, you look after my car ..." Seems
to work!

Kitchen knives that never need sharpening only need sharpening when
they get a bit blunt. Same as ordinary knives really. Scalloped edges
easier to get a good edge however - for ordinary purposes like cutting
bread. Best knife we have was grandparents carving knife - very
ordinary sheffield plain steel not stainless with "ivory" handle. Must
be 80 years old or more and apparently indestructible and keeps good
edge with use of a matching steel which is worn nearly smooth. Got the
matching carving fork too - does a brill job on the old sunday joint
(meat that is).

cheers

Jacob

On 27 Jan 2005 15:35:24 -0800, wrote:

Kitchen knives that never need sharpening only need sharpening when
they get a bit blunt.

I know not a true 'edge' like some of the knives being mentioned here
but I can't remember EVER sharpening the Kitchen Devil 'utility' knife
in the 10 odd years we had it. And that was after cutting basically
'anything' that needed cutting including cardboard boxes and those
hard plastic straps you get round big packages. I would grab it even
going for a craft knife if I wanted to cut something softish, quickly.
'She' would then have to track it down "why isn't the Devil in the
draw?" sorta thing ;-) It would still do a good job on a tomato?

Same as ordinary knives really. Scalloped edges
easier to get a good edge however - for ordinary purposes like cutting
bread. Best knife we have was grandparents carving knife - very
ordinary sheffield plain steel not stainless with "ivory" handle. Must
be 80 years old or more and apparently indestructible and keeps good
edge with use of a matching steel which is worn nearly smooth. Got the
matching carving fork too - does a brill job on the old sunday joint
(meat that is).

LOL. We rarely have a 'joint' (of meat) and if we do we (she) manages
to cut it up with 'something' (don't think we have a 'carving knife'
at all).

All the best ..

T i m

On Thu, 27 Jan 2005 09:52:36 GMT, "al"
wrote:

"Dave" wrote in message
roups.com...
Don't know, but we just got an Ice Bear ceramic zirconium knife from
Axminster. Apparently it's only posible to sharpen it with a diamond
whetstone - if it ever needs it. This thing is so sharp it's scary.
Dave

It's quite a simple equation when it comes to sharpening really. The
material you sharpen with has to be harder than the blade you're sharpening.
Otherwise it can't grind away the metal/ceramic.

You can quite easily buy sharpeners for ceramic and other hard blades (just
because the word "diamond" is mentioned, doesn't mean Pussy Galore's about
to come marching in!!). However, hard blades will never hold a good edge as
you just can't sharpen it like a good workable metal blade.

A point demonstrated by the guys in the kebab shop who seem to
re-sharpen their long carving blades at every carving?

All the best ..

T i m

"T i m" wrote in message
...
A point demonstrated by the guys in the kebab shop who seem to
re-sharpen their long carving blades at every carving?

All the best ..

Indeed. Actually, they're not sharpening the blade all the time. If they
were it would wear away too quickly. What a steel does is true the edge.
At a microscopic level (and often not if you cut onto hard surfaces!!), the
blade folds over slightly when you use it and looses its edge. Using a
steel shouldn't really remove any metal (your steel should be just that -
not some nasty ultra abrasive thing!), it's just meant to true the blade
again and should be done almost every time you use the knife, depending on
the softness of the blade. Helps keep a perfect edge.

Then every month or so perhaps (depends on how much it's used ... but in a
kebab shop, I should think at least this often) it is professionally
sharpened using stones (ie. you are removing metal to form the correct blade
angles again). If the blade is thick at the top and thin at the bottom like
a cleaver, this will eventually not be possible as you'd need to remove too
much metal to produce the cutting angle. With a constant thickness blade,
you'll eventually (many many years) just wear upwards.



a

Chris wrote:

Just seen some knives in Tesco that allegedly never need sharpening!
Scam? Or possible? What's the technology?

Tri-metal blades perhaps, or some other laminated blade with a V-hard
core and soft outer layers.