Boiling knives to disinfect?

johnniet

johnniet

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I just did an unrelated search in the Spyderco forum and found a knock-down drag-out fight over whether and how to disintect a knife that might have been exposed to blood-borne pathogens.

Surprisingly, only at the end did anybody suggest putting the knife in boiling water for a while.

Is there some reason why that's a bad idea?
Will a stainless-steel rust from a few minutes in boiling water every few weeks?
Will the steel temper be affected at 212F ?

Is boiling not an adequate method to some pathogens? (I have heard that prions have been know to survive autoclaving. But I don't know how much of a risk that is for most of us, or whether autoclaving is always more effective than boiling water.)
 
think for some pathogens/viruses, you gotta boil for at least 20 minutes and maybe even higher at 130C?

if I want to disinfect, I'd probably follow what the same methodology as filtering/purifying water - alcohol, boiling, UV, some chloride treatment (this may not be good as it causes rust because of the sodium element, and also discoloration).

any views?
 
I'm not sure if this is actually helpful, but here it goes anyway: there's a German oil called Ballistol (used to clean guns, knives and machine parts). It not only prevents corrosion, but can also be used to clean wounds.
I don't know if you can buy that stuff in the US. If not, e-mail me and I'll send you a bottle.
 
You won't affect the temper at boiling temperatures. You have to be well over 300 degress F before you start to get into the heat treatment area.
 
Boiling water will probably wreck the finish on your handle. Depending on altitude (I live at 7,000 feet) it can take a long time to be thorough. That is why they developed autoclaves--to reach higher temperatures. Mechanical cleaning helps a lot when you have hard surfaces. First dissassemble the knife if possible. I would use a commercial disinfectant that was intended to be used on plastic surfaces. I would scrub with a soft toothbrush. I Would also clean the blade with alcohol or acetone to remove resinous dirt that might hold some pathogens.
 
Is there some reason why that's a bad idea?
Click to expand...

No. Boiling is a proven method of disinfecting surfaces.


Will a stainless-steel rust from a few minutes in boiling water every few weeks?
Click to expand...

No.


Will the steel temper be affected at 212F ?
Click to expand...

No.


Boiling will leave the knife utterly unlubricated. So, you'll want to throughly lubricate it when you're done. Obviously, some materials such as wood shouldn't be boiled. Micarta and G10 will be fine.
 
As Quiet Storm said you HAVE to brush all the dirt out before boiling. As a rule of the thumb, the knife must look perfectly clean to you before boiling it. Same applies to any surgical instrument (specially for mouth instruments) and to water.
Unfortunately, many people think that cloring or boiling the water will kill everything, but unless it has been properly filtered you are not doing much.
Have in mind that the container you boil it in must be also clean.
 
I'd rather use a can of spray disenfectant(Lysol, Oster hair clipper spray, etc.) followed by antibacterial dish soap and hot water.
 
Ballistol is available in the USA.Temper wouldn't be bothered till about 400F .( knives should really be tempered at least 400F from a metallurgical stand point.)
 
Why bother going to all that trouble when good old rubbing alcohol will do just fine? :confused:

And I am very curious as to why you would feel the need to boil one every couple of weeks.
 
It is not necessary to physically clean an object before thermally sterilizing it. Dirt is not the cause of infection, germs (bacteria, fungus, and viruses) are.

High temperature will cause the large protein molecules in all germs to break apart. All that is necessary is to get those large molecules up to that high temperature.

Breaking the large molecules is how just about all disinfecting works. X-ray serilization works this way. The energy from the X-rays breaks apart the large molecules. UV serilization works the same way. Irradiation works the same way (In fact, this is also how radiation treatment for cancer works. The enegy in the radiation beam breaks the large molecules (especially the mother of all molecules, DNA) in the cancer cells. Of course this also damages the healthy cells. So, what they do is shoot the radiation in at multiple angles intersecting on the tumor.). Chemical disinfectant works the same way. Chlorine is a very polar molecule that breaks down other, weaker molecules (in fact, this is how chlorine bleach works in your laundry. Many color pigments are large molecules, especially the stuff that tends to stain our cloths. Chlorine bleach breaks down those molecules. This explains why chlorine bleach is useless against some stains. Rust stains, for example, are iron oxide. It's a very simple molecule with a very tight bond. You can pour a whole bottle of Chlorox on it to no aide.) Alcohol is also a very polar solvent that attacks large organic molecules and breaks 'em down. Do, it's a good disinfectant.


The problem with dirt is that it can act as an insulator and protect germs from heat, radiation, and chemicals. So, for thermal sterilization, you have to allow enough time at the heat to penetrate the insulating dirt and get to the actual germs.

In fact, heat is how dirt samples (please, we say, "Soil" samples) are often sterilized.

Keep in mind that products like Lysol and alcohol are sold as "disinfectants," not as sterilizers. If you read the package, you'll see that Lysol claims to kill something like 99.9% of germs on smooth surfaces. The blades of many knives are not smooth. The problem on a bead-blasted or brushed surface is that germs can get down into the surface. Liquids such as alcohol and Lysol have surface tension that prevents them from flowing into those tiny cracks and pits even if you totally dip the blade into the chemical, even if you leave it in there for hours. The surface will be disinfected, but not strictly sterilized.
 
Adhesives don't like heat. I don't know what the average temp would be for glues, epoxies and Loctite(s) to begin to break down are, but I do know some will break down at 212 degrees. Just be aware of the construction of your knife.
 
Originally posted by Walking Man
I am very curious as to why you would feel the need to boil one every couple of weeks.
Click to expand...

I wouldn't -- but at least one of the guys in the previous thread was an EMT who might get his knife exposed to real pathogens more often.
 
Some one in the daily route of an emt would have an autoclave. If it's an issue you could flash it. if the knife isn't thoroughly cleaned, this will bake any protein (blood) left on the knife and it will look like rust. I would suggest a good cleaning with alcohol or bleach. There are a couple of products on the market one is called Cidex, another is Wavicide a search online will give some info.
 
I'm not so sure that it's that necessary to sterilize a knife unless you're going to use it for surgery. Granted, viruses and bacteria can live on the surface of a knife, but many times, it's in some sort of carrier fluid or material... Clean that material off and the offending bugs and germs are gone. Most people don't autoclave, bleach, or boil their eating utensils, and restaurants here in New York State is only required to wash their dishes with hot water at a temperature of 180 degrees. As for preparing food, whatever you're going to be preparing is going to have hundreds of different bacterias and viruses more than whatever you're using to cut, poke or spoon it with so a sterile utensil isn't going to help...
 
BE careful, a lot of the epoxies popular will soften at poiling water temps and could cause your knife handles to come apart.

Besides that, Lysterine is a pretty strong disinfectant and could be used in a pinch.

jmx
 
By the way, another way sterilize things is cold. The AIDS virus, for example, won't survive much below body temperature. Mearly putting the knife in the refrigerator should kill AIDS virus.

By the way, ordinary tap water kills the AIDS virus on smooth surfaces. The AIDS virus is a very delicate virus that only survives in very specific conditions which is why it just about only spreads with bodily fluids and direct, person-to-person contact.

Water expands when frozen. When the water in a cell freezes, it expands and breaks the cell membrane thus destroying the cell. Freezing will kill cells. That's what happens with frost-bite. Just about all bacteria die when frozen. There are a handfull of bacteria that have an internal anti-freeze that protects them. These are primarily found in arctic climates and I'm not aware of one that infects people.

Some bacteria, Anthrax, for example, and fungus produce spores that can survive freezing. This is how these germs survive the winter. But, they need time to do this. Put your knife in a freezer and it will freeze faster than the bacteria or fungus can switch to spore-producing mode.

Many viruses, however, will survive freezing, at least in an ordinary freezer.
 
Prions, which are rogue proteins that cause mad cow and other wasting diseases, are NOT always destroyed by boiling.

Frankly I would hesitate to use a knife that took apart an infected animal ever again on potential food. And I'd make sure I never was cut with it. On the other hand, a good washing and bleach would perhaps make it reasonably safe.

A lot of the equation of humans and mad cow disease seems to be about HOW MUCH of the prion you eat, and as in any population, there will be people immune who could eat prions all day and never get sick-----and others who a small dose will kill them in months.

Any ideas?

Chris
 
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