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Thread: knives and what makes them dull?

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    Member thewhop2000's Avatar
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    Default knives and what makes them dull?

    OK, so I am home for a day before I have to go back to work and a friend of mine and I are having a discussion on what dulls a blade. He swears that putting a knife in the dishwasher makes the blade go dull and I think it is an ole wives tale. I do know that after shaving, if you dry your blade before putting it away, it lasts so much longer. But most dishwashers have a cycle that also dries the contents. Thoughts and can anyone back up what they respond with? Just curious
    If a dipnetter dips a fish and there is no one around to see/hear it, Did he really dip?

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    Take a knife and sharpen it, test to see how sharp it is with a peace of paper.
    Put it in the dishwasher after it wash several times, test it to see how sharp it is.

    That is the only you will know if it a problem with your knife.

    Tell us what you found.

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    Member thewhop2000's Avatar
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    Heck, I was hoping someone else already did it and could tell me!!! LOL. I'm working 7-10's and am too tired but to come home and eat and then sleep. Anybody else have something? I'm sure the knife makers would put out something if it was indeed true, not wanting their products to seem inferior.
    If a dipnetter dips a fish and there is no one around to see/hear it, Did he really dip?

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    Supporting Member iofthetaiga's Avatar
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    Quote Originally Posted by thewhop2000 View Post
    OK, so I am home for a day before I have to go back to work and a friend of mine and I are having a discussion on what dulls a blade. He swears that putting a knife in the dishwasher makes the blade go dull...
    Does this discussion involve drinking, by any chance?
    ...he who knows nothing is nearer to truth than he whose mind is filled with falsehoods & errors. ~Thomas Jefferson
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    Good question. Got me curious, so I did a small search.

    First, my reaction would be slight corrosion to the edge by the hot water and dish detergent... likely more of an effect on carbon steel vs SS.

    Section from web discussion...

    I found this about hot water: Even “”stainless steel” can rust if it is put together with steel wool into a sink. The sink and the knife blade will rust! Use a pad of brass wire (Goldilocks) a 3 M green pad or a plastic scourer to clean the steel. Avoid submerging the blade in excessively hot water as the edge (which is only one micron thick) will change its temper and become brittle. After the first stroke, the brittle edge will break and the knife becomes blunt again, needing to be re-sharpened

    So, I tend to agree there could be a degree of dulling to the cutting edge by running through a dish washer. As well, I think that no matter the method of cleaning, a good sharpening technique would be called for as part of the routine maintenance.

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    Supporting Member bullbuster's Avatar
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    My .02...
    Years ago, I had a float plane pilot show me how lake water sucked into his prop wore the leading edge.

    Fine crystal loses it's cut edge in a dishwasher.

    I might let the old lady get away with some of my harder blades going in. I catch her putting my carbon knives in the dishwasher, she hears about it. }:>
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    Member Rancid Crabtree's Avatar
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    As a custom knife maker I have my doubts about the dishwaher dulling knives. The fast moving water and heat should not dull a blade.

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    Member akgun&ammo's Avatar
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    I run knives thru sa dishwasher alot...


    after twelve or fourteen hrs cutting up meat- it's easy to place them all in the top shelf and let it run..

    if awake when finished, take out and dry

    if not- they dry by the heat of the washer

    I also sharpen all the knives before using again


    If a small bit of the edge is ruined.. that would be "sharpened" off anyway

    so, use the dishwasher if you wish- handwash if you don't trust modern conviences



    Chris

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    I only handwash mine because I don't want my carefully honed edge clanking around against ceramic and metal surfaces, and so that the wife doesn't grab in there blind for a coffee cup and cut herself.

    What makes knives dull IMO is cutting things with grit (hide and hair) and things that are nearly as hard or harder than they are (bone). When I do a moose I have two folding knives, one is for meat cuts, the other is for cuts against bone, I never have had to sharpen mid animal.

    Oddly enough, if you use a sheet of UHMW as a cutting board, that stuff is actually really hard and is tough on knives. We use a sheet of replacement side boards from a hockey rink (which is essentially uhmw) at our moose camp and while it cleans up great and we love it for the sanitation aspect, it can take a toll on your edge.

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    Member OKElkHunter's Avatar
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    Obviously you don't own a boat, if you did, you'd know that moving water is an abrasive, not a harsh abrasive, but an abrasive none the less because it contains traces of minerals and wears away propellers, strips wax from the bottom of the boat, strips paint from the bottom of the boat and erodes the hulls of boats over time. Knives have very fine edges and even very soft abrasives can wear away the edge dulling it.
    I also make knives and tell everyone that has purchased or I have given a knife not to put them in the dishwasher.
    I once visited the Grand Canyon, which, according to archeologist, was formed by water eroding away the rock.
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    I personally think the main issue is the blade bouncing against either other things in the washer or the rails themselves. As OKElk states the minerals may be present but so are large granules if using powder detergent/soap. I like to wash my good knives in warm water and dry them immediately.

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    Mine go dull in the clothes drier but that's another story.

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    Member OKElkHunter's Avatar
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    Another problem with dishwashers is the high heat. Most nice knives have bone, antler, or exotic wood scales and the high heat combined with harsh detergents used in dishwashers will eventually ruin those types of scales. If the knife has synthetic scales, the heat could warp or melt the scales if placed too close or it falls to the bottom where the heating element in the dishwasher is. I don't even let my wife put her kitchen knives in the dishwasher. You may get away with it for a while, even years, but eventually one is gonna get messed up, and it will probably be the best or most expensive one you own. It only takes a couple of minutes to hand wash a knife, so why be lazy about it and risk ruining a good knife.
    BTW, anything you cut dulls a knife, even paper. The harder the steel, the longer and edge will last, but all steel knives will eventually need sharpening. Another thing, never let your wife use your best fillet knife to bone chicken, those chicken bones are hard on the thin edge and it takes forever to get them back to pristeen condition.
    “Don't expect to build up the weak by pulling down the strong." ~Calvin Coolidge~

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    Paper and cardboard in particular are hard on it. Take your hunting knife and break down a bunch of boxes with it then try to cut a rubber band....not good.

    I still don't buy the high heat issue on the metal but I believe and have seen the effect of heat and detergents on other knife components. Not mine luckily.

    Also, I use a magnet bar to hold my knives. I'm sure the contact of attaching the knife doesn't help the edge, but I think it's much better than being left loose in a drawer or even most blocks.

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    Quote Originally Posted by Catch It View Post


    Also, I use a magnet bar to hold my knives. I'm sure the contact of attaching the knife doesn't help the edge, but I think it's much better than being left loose in a drawer or even most blocks.
    +1
    This is recommended by many makers and chefs as it keeps any contact away from the actual edge (as long as careful when placing it- LOL)

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    Member OKElkHunter's Avatar
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    High heat wasn't directed towards affecting the metal, but the scales. Also, some scales are attached with epoxy, which can be affected by the heat.
    Quote Originally Posted by Catch It View Post
    Paper and cardboard in particular are hard on it. Take your hunting knife and break down a bunch of boxes with it then try to cut a rubber band....not good.

    I still don't buy the high heat issue on the metal but I believe and have seen the effect of heat and detergents on other knife components. Not mine luckily.

    Also, I use a magnet bar to hold my knives. I'm sure the contact of attaching the knife doesn't help the edge, but I think it's much better than being left loose in a drawer or even most blocks.
    “Don't expect to build up the weak by pulling down the strong." ~Calvin Coolidge~

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