Cleaning Electronics with 99% Alcohol

Lucky enough to have a bottle of 99% alcohol at home.

Was going to pour some into a spray bottle and use it for routinely wiping down phone, keyboard and mouse.

Is there any risks with using this strength of alcohol on consumer devices? Should i dilute down? Seems over 60% is able to kill bacteria.


  • +11 votes

    Just drink it like a normal person.


    Dilute it to 60%


      I know most say to do it with distilled but can i use tap water? Its only keyboard/mouse/phone which get covered in marks anyway, not fussed about a couple mineral marks.


        Tap water is fine. Most places in Oz have pretty low mineral water anyway.

        As pointed out IPA can damage some things, like lettering on plastics.

        About 90% is typically used for cleaning. IPA dries your skin out, try not to get too much on your hands. (For hand sanitiser, this is why you add a bit of gycol or similar.)

      • +1 vote

        I'd avoid using tap water. It'll usually work but the whole idea is you are cleaning electronics - tap water has residual amounts of calcium, magnesium, etc. When your tap-water/alcohol cleaning solution evaporates, those residuals are left behind. You do not want it on your electronics: that's one way to get electrical shorts. It may not happen often but that's the risk.

        99% alcohol will evaporate and leave almost nothing - exactly why it's used for electronics. Diluting with pure distilled water is fine - no metals or other chemicals in the water. You can actually use distilled water to clean electronics too as distilled water won't conduct electricity: it has no ions, just pure H2O. It just won't evaporate as fast.

    • +2 votes

      No don't dilute it. Use it as is and if any thing dilute it to 70% max for personal use and to clean bacteria. Isopropyl alcohol is used straight to clean PCBs and other components on the regular. The more it is diluted the more chance you have of shorting stuff out. That being said i have used 70% for a few different things and it was fine but it can leave spots while 99% isopropyl alcohol should dry spot free.

  • +4 votes

    Why you want to do that when you at home? Stop wasting alcohol


      Because phone particularly gets put down on a whole bunch of different surfaces, gets touched a lot (as is evident but complete coverage in finger prints. Its a contact point that transfers thereafter to just about every other surface as we continuously use our phones throughout the day.

      I also have people in my house who still have to work who then touch door knobs which i will then also touch, followed by my phone.

      • +2 votes

        So everyone in your house hold wearing gloves, glasses and masks as well? 🙄 And changing them so often ?


          No that's obviously extreme on one end of the spectrum.

          Do you disagree that phones/mouse/keyboards are breeding grounds for bacteria?

          I think taking 5 seconds to wipe them down every now in then is far from the extremes you're referencing.

          • +1 vote

            @ptenkae: Yes but I would still clean it once a month still.

            Wash my hands each time sneezed or after toilet visit, after or before eating food etc with soap.

            Only use alcohol based hand sanitizer on the run. Or shopping etc.


            @ptenkae: Sure, your kb/m are breeding grounds for bacteria so wipe them down if they are filthy (visible dirt on the surface) but not because of cov19. You'll be contaminating them as soon as you use them again and that's why it's a waste. Best bet is to wash your hands either with soap or maybe with a couple drops of the diluted alcohol IMMEDIATELY after leaving the desk.


    (70%) might be okay, however usually we use 99% IPA, which has to be ordered from chemical suppliers (and is considered hazardous since it's quite flammable). It's usually okay to clean with water, so provided the water was pure and was allowed to dry before power was applied it might be okay to use water+IPA and a soft brush.

    Another concern is what exactly is in the remaining 30%. If it is drug-store (pharmacy) "rubbing alcohol" it may contain other additives that can leave a residue which could affect the operation of electronics. Most of the stuff available from local pharmacies here leaves a nasty white residue, and I would not suggest using it.

  • +7 votes

    Dilute it to 70% with some distilled water and you have sanitiser.

    The sweet spot of how effective it is peaks around 70%~.
    99% concentration is less effective than 70%.

  • +2 votes

    At the prices some people want for that stuff these days, consider selling it to fund your early retirement

    On a more serious note, high concentration alcohol can damage the oleophobic coating on smartphone screens so be careful with the smart phone at least. Put on some kind of screen protector first before using alcohol on it or use another chemical that won't damage the coating


      Good point, have a screen protector which i believe also has its own olephobic coating. Will make a note to not hit the crevices not covered with the alcohol.


    You'll probably strip the lettering/protective layering from cheap keyboards, and other devices.

    I still have 3x 5L containers from the 2008 deal (kept in a temp controlled server room 16c), and have been pondering what to do with it:


    Isopropyl alcohol at 99% is used to clean electronic components, because it evaporates leaving no residue.
    99% “alcohol” is just metho without the nasty tasting stuff added.
    It could react with some plastics, I guess, like the oleophobic coating mentioned above.

    I’m much less worried about surface exposure than from someone else coughing out billions of fresh virus particles. If you aren’t a health care worker in an unsafe environment, its hard to see how your electronics could be contaminated.

    Wash your hands probably remains the best bet.

    If you really must, I would not follow advice to water it down. Water and electronics aren’t a good combination.

  • +2 votes

    Ironically, purer is not better and 99% isopropyl alcohol is considered less effective than 60-70% isopropyl alcohol, so you should dilute it down to that range for it to work best as a disinfectant.

    The extra water content reduces the evaporation time, increasing contact time with pathogens. High concentrations also cause immediate coagulation of proteins, and this might cause a protective layer that prevents other proteins from being coagulated further.

    Bear in mind though, if you're really protective of you device/keyboard/mouse, isopropyl alcohol doesn't play nice with some plastics, rubbers and paints; it might make your keyboard keys fade faster, or make the plastic more brittle. Also, it can wear out the oleophobic coating of your phone screen and potentially the antireflective coating of the camera as well. Personally though, as someone who works in a hospital, I wipe down my phone with isopropyl alcohol every day and haven't had a major issue so far; and we wipe down the keyboards of our hospital computers regularly too.


    I use a mild hand or dish soap solution. Only use a few drops of either to a litre of water.

    You can actually fully submerge electronics in water + surfactant if it's really dirty. Obviously completely dry it before use again.


    For those saying not to clean electronics I think it's good practice but mainly for your phone that you bring around with you when you go out. E.g. after a grocery run you probably touched a trolley handle and then touched your phone. So once you get back wash your hands and wash your phone! I don't really use fancy stuff though, since I have a case I mainly wipe down the case with sanitiser or soapy water. Phones these days are water resistant so it should be fine with a bit of a water. Probably would need to be careful if you have screen cracks though.


    I've been using Isowipes to clean computers and all sorts of things for many years.


    Whatever you do don’t use spay and wipe. Leaves this white streaky layer and hard to get rid of


    Lucky enough to have a bottle of 99% alcohol at home

    Is that methyl alcohol?
    Is that ethyl alcohol?
    Is that isopropyl alcohol?

    One is toxic. One is for drinking ;-] . One is for cleaning.

    Don't get mixed.


      I doubt average Joe will get his hands on methanol. That's the stuff that makes you blind when you drink it.

      Methylated spirits is just ethanol + denaturing agent. It will probably disinfect but will leave the denaturing residue allover, so not suitable.

      For disinfecting you can use either ethanol or isopropyl alchol, but needs to be diluted to minimum 60% to be effective.


    is there still anywhere in australia with stock of isopropyl alcohol? i'm struggling to find anything and haven't found anything in supermarkets for the last 3 weeks. unsure how often things are stocked at my local supermarkets. there is never any cleaning products or soap.

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