I want to make homemade "milk of magnesia" as a suspension containing only magnesium hydroxide and water.
I see that I can purchase a bag of magnesium hydroxide powder. Can I use this to make a suspension or is there a multi-step process?
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2$\begingroup$ I guess the first question to ask is why you want to make it at home. The store stuff is dirt cheap... $\endgroup$ – Zhe Jun 15 '17 at 17:24
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$\begingroup$ One gallon (about 4L) of milk of magnesia is about [26 USD. ](google.com/…). 500 g (17.6 oz) of Mg(OH)2 is about [17 USD ](google.com/…). Since milk of magnesia is 8% by mass, that gallon only has 290 g of Mg(OH)2 in it. The materials are cheaper to make it yourself, but the time and effort might be worth more than 10 USD. $\endgroup$ – Ben Norris Jun 15 '17 at 18:32
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2$\begingroup$ If you plan to ingest it, there may be safety issues involved. Rule 1 of amateur chemistry is don't eat anything you make... $\endgroup$ – Zhe Jun 15 '17 at 18:40
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$\begingroup$ There are some good reasons to make Milk of Magnesia at home. One, I can't presently purchase it the stores (Covid-19 shortage I guess), I use it in a deodorant recipe so I'm not ingesting it and by making it myself I am not shipping water, saving on plastic and I know what is in the concoction. Thank you for helping me. $\endgroup$ – Brenda McFarlane Jul 18 at 20:38
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Milk of magnesia is typically just a suspension of about $\pu{8\%}$ wt/v (i.e. $\pu{8g / 100 mL}$) magnesium hydroxide in water. To get a good suspension you will want to have very fine magnesium hydroxide. Ideally, it should feel like flour when rubbed between you fingers. Regardless, there will be some settling and you will need to shake it thoroughly prior to each usage. No other preparation should be necessary.
