When we were kids and used to run around barefoot, we often used to get thorns in our feet. My mom used to use a needle to dig them out, and would dip the needle in rubbing alcohol to sterilize it before beginning. Does this really work?
IIRC, it does a pretty fair job of killing most of the germs, but only if the alcohol is allowed to dry on the item being cleaned. You can’t just wipe it off right away.
QtM, MD
It’s not rubbing alcohol, but in 3 labs I’ve worked in, we used a 70% solution of ethanol (drinking alcohol) to wipe down the insides of laminar flow hoods, our instruments, and our hands to create a “sterile” environment inside.
Sorry for a minor hijack, but isn’t that what rubbing alcohol is?
Rubbing alcohol is isopropanol, not ethanol.
Kinda depends on how you define “sterile”. Alcohol will kill just about anything if it’s on there long enough, but it evaporates pretty damned fast, often too fast to kill the tougher stuff. It will usually greatly reduce the amount of bacteria and such on something, though. Still, I wouldn’t really call that “sterile” so much as “less contaminated”.
The needle we used to get was first heated over a gas flame on the stove, I’m not sure if that’s any better.
I remember our barber used to have a big jar of alcohol he used to store his working combs. Now they seem to use UV light devices.
Since I started brewing beer and wine, I’ve learned a few things about cleaning, sanitization, and sterilization.
If your metal object has not been cleaned before you dunk it in alcohol, microbes can survive within any “goo” that might exist in the cracks and crevices.
Say, for example, you have a quart mason jar, which you fill halfway with sugar water, and allow to sit in the open air to be colonized by various bacteria and wild yeasts, until all the the water evaporates. You’ll be left with thick sticky gunk in the bottom of the jar. In this case, merely dunking it in alcohol, or even soaking it (depending on various factors), will probably not effectively sterilize the jar.
It’s an extreme example, but you see my point.
If the metal object really needs to be sterile, make sure it’s cleaned of any gunk or deposits, and soak it for minutes rather than seconds.
In practice, there probably isn’t much food for bacteria on a sewing needle in the first place, and a quick dip in alcohol will probably sufficiently sanitize it.
Or in the bad old days, methanol.
Many years back the regular procedure was to sterilize all medical paraphernalia in rubbing alcohol. Needles were used over and over and were kept in a container of alcohol. Today we throw away needles, which not only means the one being used is lots more sterile, but also is sharp and doesn’t hurt like dull needles that had been used many times. I believe drinking alcohol was mostly used as an antiseptic in cowboy movies.
Alchol must be 70% to sterilize. weaker won’t do and stroger will cause the outer covering to harden. (I think)
Spelling and grammer subject to change without notice.
A flame is actually an excellent way to sterilize metal. Bacteria are just tiny bags of protoplasm that dry up or burn quickly on red-hot metal. Even their spores, which can be tough little buggers, will burn or be so messed up sthat they don’t pose much risk (due to protein denaturation, etc.) Even if a few live bacteria survive a cursory flaming, they won’t hurt you, if they’re in no shape to multiply.
UV mostly works by messing up DNA (e.g. creating thymidine dimers, and base conversions.) It’s slower than alcohol, but more effective against viruses if the UV exposure is long enough. Dilute bleach solutions are also used to chemically ‘sterilize’ viruses, which have no physiology and aren’t really alive to begin with.
Alcohol is a perfectly decent sterilizing agent, but even a good soap cleaning will make the needle far cleaner than the thorn you’re digging out. [BTW, Eleusis is right about using a clean needle, even if you’re going to sterilize it.] The additional sterilizing effect of alcohol is mostly useful when needles are often re-used [home first aid or medical settings]. “You don’t know where it’s been” applies more than ever to needles that may recently have been inside a pus-filled absess.
Now aren’t you glad we mostly use disposables now?
Interestingly, though ethanol (and isopropanol) works mostly by dehydrating the bacteria, 100% or 95% ethanol [li] don’t sterilize nearly as quickly or well as 70% ethanol. A few seconds exposure is adequate: As little as 30 secs will give results essentially as good as days of immersion. As you can imagine, sterilizing with ethanol been well studied, and 70% ethanol is widely sold, precisely because it was found to be nearly optimal. So if you MUST sterilize with vodka or grain alcohol, as in some old movies, aim for 140 proof, even if you have to dilute it a bit.[/li]
100% ethanol is uncommon outside of chemistry labs, because ethanol will avidly suck water out of the air, if necessary, to create a 95% water/ethanol azeotrope. You can’t even distill it to better than a 95% solution; it’ll bring 5% water with it. That’s why 95% [190 proof] is the practical limit for grain alcohol or liquors. To make ethanol stronger than this, you have to run it through a bed of anhydrous dissicants [special water-sucking chemicals], – if you think shaking bruises gin, try running it through anhydrous copper sulfate.
Wow, this is interesting. Our local grocery store sells 70% isopropyl alcohol, of course, like everybody else … but they also sell 99% isopropyl alcohol, which I’ve never seen at any other grocery store. If 70% sterilizes better, why do they sell 99% as well? Are they just preying on ignorance?
I use the 99% alcohol to clean out computers that stuff gets spilled on, figuring that 99% alcohol will evaporate faster and leave less residue than 70% will. Now I wonder if that’s true.
[QUOTE=KP]
Interestingly, though ethanol (and isopropanol) works mostly by dehydrating the bacteria, 100% or 95% ethanol [li] don’t sterilize nearly as quickly or well as 70% ethanol. A few seconds exposure is adequate: As little as 30 secs will give results essentially as good as days of immersion. As you can imagine, sterilizing with ethanol been well studied, and 70% ethanol is widely sold, precisely because it was found to be nearly optimal. So if you MUST sterilize with vodka or grain alcohol, as in some old movies, aim for 140 proof, even if you have to dilute it a bit.[/li]
[li] 100% ethanol is uncommon outside of chemistry labs, because ethanol will avidly suck water out of the air, if necessary, to create a 95% water/ethanol azeotrope. You can’t even distill it to better than a 95% solution; it’ll bring 5% water with it. That’s why 95% [190 proof] is the practical limit for grain alcohol or liquors. To make ethanol stronger than this, you have to run it through a bed of anhydrous dissicants [special water-sucking chemicals], – if you think shaking bruises gin, try running it through anhydrous copper sulfate.[/li][/QUOTE]
I know a girl who can suck like anhydrous copper sulfate. She knows how to create a hard, throbbing azeotrope, sure enough.
For cleaning electronics, the less water the better. I can only get 90% Isop. at drug stores. For the 99% stuff I have to go to electronics supply houses. In particular, 99% stuff is best for cleaning video heads. (So a little of that goes a long ways.)
FWIW, I have a bottle of Lavacol brand rubbing alcohol, whose ingredients are listed as “70% denatured ethyl alcohol” [ethanol].
I’ve always had the understanding that “rubbing alcohol” = “isopropanol”, so I was surprised to see this on the label.
One common way of using ethanol to sterilize things in the lab is flaming - you dip your object in the ethanol, take it out, then light the residual alcohol on fire.
Interesting. I’ve always been a little skeptical of the concept of “bruising” gin, but I’ve never heard this explanation before. Can you elaborate on this? If I read you correctly, the gin is bruised by “sucking up” too much water, which the shaking somehow facilitates. Is that right? Can you bruise gin that doesn’t have ice in it (sucking water from the air bubbles that get mixed in), or is the ice necessary?
I’m really curious whether bruising is something that really affects the taste in a noticeable way, or if it just gives people something to be snobby about.
The key to your query lies in the word ‘denatured’ meaning, rendered unfit for drinking without impairing other useful properties.
Ethyl alcohol, aka ethanol or grain alcohol = CH3CH2NH2
Isopropyl alcohol, aka rubbing alcohol = (CH3)2CHOH
Methyl alcohol, aka methanol or wood alcohol = CH3OH
Try again.