Demineralized water or not?

@Perry, I've read the article you wrote about differences between types of water on UL Prospector.

"Demineralized water
This water is sent through an ion exchange process and is pretty much the same as deionized water. From a formulation standpoint, there is no difference."

Do I understand that I can just as well use demineralized water for homecrafting?
I used to buy distilled/deionized water, but demineralized water is so much cheaper and easier obtainable here.

Thanks in advance!

Comments

  • PerryPerry Administrator, Professional Chemist
    Yes, you pretty much won't notice a difference if using it in your formulations.
  • Perry said:
    Yes, you pretty much won't notice a difference if using it in your formulations.
    Thank you so much Perry!

    If you don't mind me asking, what is your personal view on heating & holding the water phase?
  • PerryPerry Administrator, Professional Chemist
    edited April 2020
    If you use a proper preservative there is no reason to heat and hold.  Although, if you are making an emulsion then of course, you would want to heat the system up, hold at high temperature with mixing, then cool. But that doesn't have anything to do with "purifying" the water.

    If someone is heating and holding the water phase to reduce the viable microbial content then they shouldn't be using that water or raw material source.

    Why do you (or people who follow the advice) heat & hold?
  • Ok, but demineralized water isn’t sterile. And although I understand cosmetics isn’t required to be sterile DIY materials are compromised from day 1. Aristoflex AVC we can buy from lotioncrafter isn’t the same one Chanel uses. It was bought in a large drum and then opened and closed million times so that I can get my 50g which will last me a year. Bacteria in, dust in, random particles in. Even parabens might not be enough when all your materials are compromised and I think it must be taken into consideration. I buy distilled ultra pure with 0 ppm and I still boil right before I formulate. Once the bottle is open spores are in.
  • PharmaPharma Member, Pharmacist
    Only distilled (sometimes termed double distilled) water for injection purposes is sterile (and pyrogen free) until you open/break the bottle/vial.
    Demineralised water may contain a few more trace minerals and heavy metals but addition of a chelate takes care of that.
    Heat and hold or rather bring to a rolling boil removes air and CO2 dissolved in water. This may result in more stable emulsions (on a scientific 'scale'). Alas, once you start mixing and stirring in solids, you automatically reintroduce these.
    Also, many solids such as @ngarayeva001's Aristoflex are likely more contaminated than water. One could, if germophobia is strong enough, sterile filter water and oil phase separately through hydrophilic and lipophilic 0.2 um membranes and work under aseptic conditions... Or go and add a preservative.
  • PerryPerry Administrator, Professional Chemist
    If it is no problem to do, then it probably isn't hurting anything to do it. However, I'm not sure it's helping much. You could do a simple experiment to see if it has any impact on microbial growth.
  • Well most home crafters can’t send it to be tested for CFU. I read microbial plates sold by repackagers aren’t particularly accurate either. Is there any other option? I boil water but I just thought of it as a logical thing to do. I don’t know if it’s true and if someone can confirm this is a correct approach I would be grateful.
  • Perry said:
    If you use a proper preservative there is no reason to heat and hold.  Although, if you are making an emulsion then of course, you would want to heat the system up, hold at high temperature with mixing, then cool. But that doesn't have anything to do with "purifying" the water.

    If someone is heating and holding the water phase to reduce the viable microbial content then they shouldn't be using that water or raw material source.

    Why do you (or people who follow the advice) heat & hold?
    Thanks for your personal view, Perry! Much obliged!

    I never heat & hold, but this advice is mentioned on the Making Skincare site
    https://makingskincare.com/how-to-make-a-lotioncream-part-1-equipment-and-ingredients/
    Ok, but demineralized water isn’t sterile. (...)
    Neither is distilled water, unless it's the water for injection type that @Pharma mentions, which has had extra treatments (e.g. a filtration step to remove pyrogens etc.)
    I do understand however why you heat & hold and buy 'extra pure' water. I remember that you wrote a while ago that you had persistant/tenacious fungi problems, even with parabens. That would've made me very cautious as well. 
    Isn't there something you might have overlooked during the preparation of those formulas? If you could find that out, it might save you a lot of money regarding energy and expensive water.

    Well most home crafters can’t send it to be tested for CFU. I read microbial plates sold by repackagers aren’t particularly accurate either. (...)
    Where did you get that information, regarding the microbial plates?
    I remember a microbiologist somewhere wrote that only plates are not enough, you need an MCT as well, but that doesn't mean that the plates/slide sticks aren't accurate. The MCT goes hand in hand with slide tests.
    The problem with those slides/plates can be that expiry dates are short, I've had several times unused plates that got contaminated during transport and problems with condensation (the reason why the primary packaging around the plates at my work are also sterilized).
    I have never used slides or plates from repackers like Lotioncrafter, so I have no experience with those. Maybe it's worth a try?

  • It's from another formulation group and  I hope the author won't mind me quoting this. He is a PhD and an author of Cosmetic Microbiology. Since I am absolutely not an expert in microbiology, I have to rely on what a professional says. Although there are bacteria that tolerate high temperatures and most spores obviously tolerate high temperatures, those are not typical in skincare.
    I have an opinion on materials and which rheology modifier would work better with electrolytes, but with this, I am blind and don't even have means of checking whether I am right until I grow colonies of mould. So I use distilled water, I boil it before formulating, I use both phenonip and germall powder at a max amount (and EDTA), I bath all my equipment in 80% ethanol, try to avoid bug food and hope for the best.


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