VeggieBoards banner

1 - 12 of 12 Posts

·
Banned
Joined
·
10,763 Posts
Discussion Starter #1
Anybody know why, in those TV demonstrations, a cheap, poor quality knife will still cut a tomato, after the demonstrator uses it to try and cut a rock, or a piece of iron pipe? Yes, yes, yes. I know why. This is a quiz.
 

·
Registered
Joined
·
0 Posts
Seems to me one could cut a tomato with the edge of just about anything if the tomato is firm enough. It seems like it's harder to cut if it's softer. I've had some pretty dull knives that would still cut a tomato.
 

·
Registered
Joined
·
478 Posts
I have a set of Ginsu knives (got them super cheap off of Ebay). As crappy as their quality is, they do cut quite well. I couldn't imagine paying $30 for them though - i feel sorry for anyone who has.<br><br>
I haven't tried cutting a rock with them yet though.
 

·
Banned
Joined
·
10,763 Posts
Discussion Starter #5
What I think is happening is as follows.<br><br><br><br>
These cheap knives always have serrated edges. Knives with regular unserrated edges get dull from 3 things: (1) actually cutting things again and again and again (2) sliding against the cutting board, (3)bumping into all sorts of things, if stored in a drawer instead of a knife block. Serrated edges are dulled only by actually cutting things. The points on the serrations keep most things in a drawer from bumping into the sharpened area between the serrations. It also keeps this sharpened area from coming into contact with the cutting board. Only things that are actually being cut thru, come into contact with the sharpened edge, and gradually dull it due to the repeated contact.<br><br><br><br>
Even if you intentionally cut an iron pipe, you will only "file down" the points. The actual wedge-shaped cutting edge between the points, won't contact the pipe at all. So it stays sharp. What's left of the points after they are abraded down by the the pipe still has a shape that can poke thru a tomato's skin. Once they poke thru, shred thru, far enough for the sharp edge to contact the tomato, the sharp edge takes over and does the cutting (the points alone would have made a mess). If the the sharp edge between the points were somehow made dull, the tomato would be difficult to cut.
 

·
Registered
Joined
·
1,804 Posts
i should visit this forum more often, such interesting discussions going on in here.<br><br><br><br>
nice art work soilman.
 

·
Registered
Joined
·
8,440 Posts
my guess:<br><br><br><br>
1- they use hard tomato's that are easier to cut.<br><br>
2- the demo is fake<br><br>
3- they use a knife that is simular to the one that is sold, but from a different better material.<br><br>
4- a new knife can stand a bit of abuse.
 

·
Banned
Joined
·
10,763 Posts
Discussion Starter #9
In my experience, a "dull" seratted knife will still cut a soft tomato. So they don't have to use any trickery. Only a fairly sharp ordinary-edge knife will cut a soft tomato.
 

·
Registered
Joined
·
0 Posts
"Professional" knives set $30<br><br><br><br><a href="http://www.fatwallet.com/forums/messageview.cfm?catid=18&threadid=158906&highlight_key=y&keyword1=knive%20set" target="_blank">http://www.fatwallet.com/forums/mess...d1=knive%20set</a>
 

·
Registered
Joined
·
1,785 Posts
I bought a cheap bread knife, shown on t.v., as indestructible, never needs sharpening, even came with a life time guarantee.<br><br>
I bought it 25 years ago and it is still perfect. They were telling the truth. One of the best purchases that I ever made...
 

·
Banned
Joined
·
10,763 Posts
Discussion Starter #12
Last Visit: 03-05-03<br><br><br><br>
Mushroom writes:<br><br>
=========<br><br>
I bought a cheap bread knife, shown on t.v., as indestructible, never needs sharpening, even came with a life time guarantee.<br><br>
I bought it 25 years ago and it is still perfect. They were telling the truth. One of the best purchases that I ever made...<br><br>
=====================<br><br><br><br>
Yup. Serrated knives are the best choice for cutting bread. The sharpest ordinary knives have trouble with bread. However a sharp ordinary knife will cut right thru a soft ripe tomato just as faster as a new cheap serrated knife, and will also slice through potatoes, celery, carrots, onion, etcetera, as fast as a serrated knife. Oftentimes the ordinary knife requires less pressure to cut through. Try an orange or a grapefruit for example. A sharp knife will go right thru in one to 3 strokes; a serrated knive will require more pressure and and makes a slightly more ragged-looking surface than the regular knife. A serrated knife will tend to cause slightly more wear and tear on your cutting board surface. The main disadvantage to serrated knives is that when they do get dull, they are a lot more trouble to sharpen. A $1.70 silicon carbide stone, or a piece of 400 grit wet-or-dry sandpaper glued to a hard flat surface (like a flat glass plate), along with a little light machine oil, will sharpen a regular knife in a minute. Unless you have special devices costing maybe 100's or 1000's of dollars that sharpen all the serrations at once, sharpening a serrated knife involves finding a small curved object that can fit into each serration, and then sharpening each and every serration separately. But it does take longer for them to get dull, for the reasons I indicated above.
 
1 - 12 of 12 Posts
Top