[HN Gopher] How to grow sodium chloride crystals at home
       ___________________________________________________________________
        
       How to grow sodium chloride crystals at home
        
       Author : kdavis
       Score  : 537 points
       Date   : 2021-11-17 16:54 UTC (6 hours ago)
        
 (HTM) web link (crystalverse.com)
 (TXT) w3m dump (crystalverse.com)
        
       | djrogers wrote:
       | These are beautiful. Seems that a possible solution to the
       | problem outlined at the end of the post (they are not quite
       | cubical, but flat) would be to gently flip them a few times
       | during the months they are growing.
        
       | mh-cx wrote:
       | I've never seen this before and wonder how stable/fragile are
       | those crystals? Are they very touch-sensitive or can you carry
       | them around easily in your pocket?
        
         | nojs wrote:
         | I've done this as a kid and they're not really fragile. You
         | could definitely carry it in your pocket.
        
       | dylan604 wrote:
       | "If it looks like picture 4 or 5, let it grow anyway. "
       | 
       | Anyone got a location on picture 5?
        
         | Kikawala wrote:
         | It should say "If it looks like picture 3 or 4, let it grow
         | anyway."
        
       | ulzeraj wrote:
       | I'm ashamed to confess that licking those pretty cubes was the
       | first thing that passed through my mind.
        
       | at_a_remove wrote:
       | I have often wondered what sorts of crystals that you can grow at
       | home that are relatively hard, sturdy, long-lasting.
        
       | jackallis wrote:
       | looks like a fun a project to work with kids
        
       | anorphirith wrote:
       | is that even legal ?
        
       | ffhhj wrote:
       | Is it possible to grow crystals in moulds to give them custom
       | shapes?
        
       | Borrible wrote:
       | https://en.m.wikipedia.org/wiki/Chemical_garden
        
       | fcatalan wrote:
       | My daughter has this as an school assignment, with some
       | implication that it is some sort of a contest, and we managed to
       | grow quite a few of similar quality to the seed crystals on the
       | site in 4 days, which was the original (poorly thought IMO)
       | deadline. The trouble is that no one else was able or cared to do
       | it so fast, so the deadline has been slipping for a couple weeks
       | now, with our best crystals going to school and back a few times,
       | getting scratches and broken bits instead of nicely growing
       | undisturbed. A bit discouraging. I'm now remembering how
       | frustrating was for me to take school related things too
       | seriously and discover you cared more than your teachers when I
       | was her age.
        
         | 5faulker wrote:
         | Could be a good self-sufficiency project too.
        
         | dekhn wrote:
         | We managed? When I was a kid I never got help from my parents
         | on these projects, and hated the kids who "won" because their
         | parent helped.
         | 
         | On the other hand, being the competitive person who excels in
         | science projects is often a very good predictor for being able
         | to handle the tedium of a scientific lab job.
        
           | JKCalhoun wrote:
           | I was enamored with "Things of Science" when I was a kid. So
           | much so I began collecting them off eBay, scanning the little
           | science booklet and sharing them for posterity.
           | 
           | As such I love DIY science like this.
           | 
           | Regarding crystals, I have scanned in and cleaned up two
           | projects relating to crystals:
           | 
           | http://underlandia.com/index.php/2017/09/24/things-of-
           | scienc...
           | 
           | http://underlandia.com/index.php/2020/08/21/things-of-
           | scienc...
        
             | zt9 wrote:
             | @JKCalhoun just got this account to say thank you for this
             | - I am home schooling with my kids this year and this is a
             | gem of a find.
        
             | germinalphrase wrote:
             | Thank you for sharing Things of Science!
        
           | detritus wrote:
           | My daughter's only 2 and a bit right now, but I can totally
           | envision an environment wherein I'm acting as an idiot sub-
           | lab assistant role, helping with the basics of her demands.
           | 
           | Of course, I'd not want to do her work for her, but more than
           | equally, I'd be quite happy to have a '5% We-encouraging' in
           | her vocabulary when it comes to her explaining herself. What
           | parent wouldn't, if they can?
        
           | dctoedt wrote:
           | The sitcom _Modern Family_ had an episode in which kids had
           | to do an egg-drop project and were helped by their respective
           | parents.
           | 
           | https://www.wikiwand.com/en/Egg_Drop
        
           | fcatalan wrote:
           | When I was a kid I never got help from my parents either and
           | I now think that I would have benefited from a bit of closer
           | attention. I developed a huge spectrum of bad practices and
           | behaviours that I'm inclined to think I could have avoided at
           | least in part. I want to think there's some space between
           | doing their homework for them and not caring about the
           | minutiae of their education, and I want to be there.
        
             | koolba wrote:
             | > I want to think there's some space between doing their
             | homework for them and not caring about the minutiae of
             | their education, and I want to be there.
             | 
             | Even showing a lack of interest in their pointless projects
             | is a life lesson in priorities and individualism.
        
               | fcatalan wrote:
               | But the project isn't pointless!
               | 
               | For example, most of my help was to make sure she took 10
               | different containers and placed them in different
               | locations around the house to increase the probability of
               | getting a few decent crystals. I discussed redundance
               | with her in the context of explaining why some of her
               | friends were not getting results from their single try. I
               | think that these practical thought patterns are extremely
               | valuable, better than creating a miniature jaded adult...
        
               | cornell532 wrote:
               | You sound like a great parent doing right by your
               | daughter. She's lucky to have you.
               | 
               | The point of school is to learn to think + learn to face
               | adversity & failure....
        
               | wilkommen wrote:
               | You're doing good. Just cause someone else's childhood
               | sucked and they feel like they learned something from it
               | doesn't mean it's a good thing. You learn a lot more
               | about how to live well from being loved than you learn
               | from being ignored and neglected.
        
               | bawolff wrote:
               | > Even showing a lack of interest in their pointless
               | projects is a life lesson in priorities and
               | individualism.
               | 
               | If you teach your kid the lesson that life sucks and
               | trying is for suckers, don't be surprised when they
               | believe it and don't get anywhere in life because they
               | never try.
        
           | spaetzleesser wrote:
           | "When I was a kid I never got help from my parents on these
           | projects, and hated the kids who "won" because their parent
           | helped."
           | 
           | I wish my parents had shown interest in stuff like this and
           | supported me to some degree. It's not about doing the whole
           | project for the kids but showing interest is super helpful. I
           | often gave up on stuff because my dad would basically say
           | "what's this nonsense for?"
           | 
           | I noticed this when read books about Steve Wozniak and
           | Richard Feynman. Their dads showed interest and encouraged
           | them to explore the world and also challenged them from time
           | to time.
        
           | csa wrote:
           | > When I was a kid I never got help from my parents on these
           | projects, and hated the kids who "won" because their parent
           | helped.
           | 
           | These can be two different things:
           | 
           | 1. Constructive help from parents has (at least) two
           | components. First, it shows your child you care. This may
           | seems small, but it's not. Second, and I think this is what a
           | lot of HNers would appreciate, is to help your child to
           | develop good processes. There is a lot that goes into this,
           | and it can be parent-centered or child-centered, but having
           | your child reflect on process and (ideally) implement some
           | good processes can really set them up for later in life.
           | Imho, parents should have to write a short narrative about
           | what involvement they had in their child's project, if any.
           | This is required at some of the local schools where I live.
           | 
           | 2. Having the parents do the project for the child is just
           | silly. Most decent teachers can see through this (assuming
           | they care). Congrats to the adult parent for winning
           | elementary school or middle school as an adult. :-/
        
             | sokoloff wrote:
             | > Most decent teachers can see through this (assuming they
             | care).
             | 
             | I entered the science fair as a kindergartner with a poster
             | project explaining how (the output color-mixing of a) color
             | TV worked.
             | 
             | Principal accused my parents of doing it; they had no idea
             | what he was talking about and protested that I'd done it.
             | So he interviewed me about it and left convinced I'd done
             | it. ;)
        
         | Waterluvian wrote:
         | I know exactly how you feel. Very frustrating and sometimes
         | disenchanting to discover they don't really care.
         | 
         | But perhaps also a good life lesson because that happens all
         | the time. It's good to try and develop a healthy self-driven
         | passion. Oh, you don't care? That's fine because I do and I
         | learned a lot.
        
       | seanalltogether wrote:
       | More discussion from original poster.
       | https://www.reddit.com/r/mildlyinteresting/comments/qvxyjg/a...
        
       | philipkglass wrote:
       | Calcium tartrate is a great high speed introduction to crystal
       | growing because it is very forgiving and "magical." You can get
       | ~millimeter size crystals in seconds. Then once you're hooked you
       | can try growing crystals that require more patience/technique. If
       | you ever saw the demonstration of lead (II) iodide precipitating
       | from solution [1], this demonstration looks similar except that
       | the crystals are sparkly and colorless instead of sparkly and
       | golden.
       | 
       | You'll need potassium hydrogen tartrate (cream of tartar), sodium
       | hydrogen carbonate (baking soda), and calcium chloride (sold as
       | DampRid or Pickle Crisp).
       | 
       | Add a spoon full of baking soda and a spoon full of cream of
       | tartar to a glass of distilled water. They should fizz together
       | as the baking soda neutralizes the acidity of the cream of
       | tartar, releasing CO2. This is what you want, since the mixed
       | neutral salt of tartaric acid is more soluble in water. Stir and
       | wait for the fizzing to die down, then gradually stir in small
       | portions of more cream of tartar until the additions stop
       | dissolving. Let the solids settle in the glass.
       | 
       | Meanwhile, dissolve a spoon full of calcium chloride in a second
       | glass of water. It should dissolve readily with a bit of
       | stirring.
       | 
       | Once residual solids have settled in glass one, decant the clear
       | liquid into another glass.
       | 
       | Now pour the clear decanted liquid into the calcium chloride
       | solution with stirring. Within seconds, you should see sparkling
       | needles rain out of the solution. These are your crystals. The
       | transition is especially striking in direct sunlight. The
       | crystals can be saved and seem to remain stable in air regardless
       | of ambient humidity.
       | 
       | I unfortunately have not seen this demonstration written down
       | elsewhere so I can't offer a citation. I came to it by personal
       | experience when I was on a crystal growing kick as a kid. (Though
       | it may well have been written down somewhere that I have never
       | come across.)
       | 
       | [1] Like in this video:
       | https://www.youtube.com/watch?v=AO67MnZaAvQ
        
         | BuildTheRobots wrote:
         | Do you know how safe the resulting crystals are to handle?
        
           | philipkglass wrote:
           | I believe that they are safe to handle. None of the compounds
           | or elements involved are toxic at moderate doses even if
           | ingested. I personally handled these crystals with bare hands
           | many times.
        
         | huhtenberg wrote:
         | Potassium bitartrate is also a great introduction to crystals.
         | 
         | Get a bottle of good red wine, 2010 or thereabouts. Uncork and
         | drink it. Now look at the bottom of the last glass, if you
         | still can, and - voila - potassium bitartrate.
         | 
         | If you don't find any, don't despair and try another bottle.
        
         | drran wrote:
         | Search for <<Rochelle salt piezoelectric crystals>>.
        
       | invalidusernam3 wrote:
       | Assuming these are edible when complete? I could imagine these
       | for fancy dinner parties where each diner gets a crystal and a
       | small cheese grater
        
         | stingrae wrote:
         | I don't think a cheese grater would work? A hammer would be the
         | tool I would go for.
        
         | darkwizard42 wrote:
         | Seems like it is edible given the only ingredients to start
         | were salt and water. I don't know about the durability though.
         | Do these break easily or are they very dense?
         | 
         | Guess we gotta grow some!
        
       | jrockway wrote:
       | Welp, this is a silly project that I have no choice but to try.
       | Looks straightforward and rewarding with a nifty end result.
       | 
       | This is a content-less comment but... great article, thank you
       | for submitting.
        
       | legohead wrote:
       | There's also "salt pyramids" [1] which are desired in Culinary
       | field for their look and texture. Be pretty cool if there was a
       | way to grow a transparent salt-pyramid.
       | 
       | [1] https://www.youtube.com/watch?v=FVEZuzEHwQk
        
         | jedimastert wrote:
         | I'm glad you linked to the Adam Ragusea video, you saved me the
         | trouble of finding it.
         | 
         | I really like Adam's videos, he does a ton of research, and has
         | a very descriptivist approach to cooking in general
        
         | hansjorg wrote:
         | There's a section about pyramids in the article:
         | https://crystalverse.com/sodium-chloride-crystals/#saltpyram...
        
       | thunderbong wrote:
       | What a fantastic article! I didn't know it was possible to grow
       | crystals like that from salt. Have to try this!
        
       | alhirzel wrote:
       | NaCl is a lensing material in the LWIR bands, this could lead to
       | very cool applications for cheap thermal cameras
        
         | teeray wrote:
         | I'm intrigued, but no nothing about lensing materials or the
         | LWIR band. Care to expand or link to a good resource for
         | learning more?
        
           | alhirzel wrote:
           | FLIR has a good handbook on some of the physics: https://www.
           | flirmedia.com/MMC/THG/Brochures/T559243/T559243_...
           | 
           | The rest is light transport, e.g. lensing via index of
           | refraction: https://courses.lumenlearning.com/boundless-
           | physics/chapter/...
           | 
           | Here's a cool article on a piece of an old spectrometer:
           | https://utsic.utoronto.ca/spectroscopy-beyond-the-visible-
           | sp...
           | 
           | More information from a distributor of optics:
           | https://www.knightoptical.com/stock/default/windows-and-
           | diff...
        
       | rbobby wrote:
       | > it will probably double in size in a week and reach 1x1 cm in a
       | month
       | 
       | TIL it takes a long time to grow a perfect salt crystal of any
       | size.
        
       | avian wrote:
       | > Indeed, table salt is often used in kids' experiments to
       | demonstrate crystallization. It's a simple activity, but the
       | results are disappointing.
       | 
       | I remember this was one of the things I tried countless times as
       | a kid. It never worked - the books showed these nice, clear
       | crystals but all I ever got was a crust of dried salt and maybe
       | one tiny crystal a few mm across.
       | 
       | I'm sure most of those "science for kids" book authors never
       | tried a single one of their experiments.
        
         | jareklupinski wrote:
         | i tried a similar 'experiment' once with sugar to make rock
         | candy, failed the first attempt
         | 
         | my grandma saw and told me to use the rest of the string and
         | sugar I had, enough for 12 more tries, and do them at once but
         | in different areas of the house
         | 
         | only two actually grew but i learned the value of spreading
         | risk and unknown unknowns ( much later, on reflection :) )
        
           | dylan604 wrote:
           | Did this as a kid as well. When I got to high school
           | chemistry, we did an experiment on super saturation of the
           | sugar. Much better results, much faster!
        
             | sumtechguy wrote:
             | hehe I did that super saturation thing as a kid. one of the
             | instructions was pour until saturation happens. It didnt. I
             | ended up with 5 pounds of rock candy.
        
               | dylan604 wrote:
               | Did you do the version where you let the super saturated
               | solution cool down slowly, and then drop a single grain
               | of sugar into it?
        
             | dekhn wrote:
             | When I wanted crystals for microscopy, I made a mother
             | liquor by pouring an enormous amount of sugar in a tiny
             | amount of water (beyond saturation) and then just let the
             | solvent evaporate in a heated chamber.
             | 
             | Made big rocks. https://en.wikipedia.org/wiki/Mother_liquor
        
               | dylan604 wrote:
               | Never heard that term before. Not sure I understand the
               | point though. After you supersaturate and then form
               | crystals, the mother liquor is just the left over content
               | that didn't make it into the crystals. What is the
               | purpose of using those remnants?
        
               | dekhn wrote:
               | mainly to get more crystals and as a growth medium for
               | existing crystals.
        
           | spike021 wrote:
           | We did a rock candy experiment in 6th grade and probably
           | attempted it a few separate times, specifically because we
           | kept having issues. I think at least one batch got moldy.
           | But, if I'm remembering correctly (this is over a decade
           | ago), we may have been placing the dishes near where sunlight
           | hit, so that could've been part of it.
        
         | carlos_rpn wrote:
         | Could it be the requirement for "Uniodized table salt"? I don't
         | think I'd be able to find it around here, and I can't think of
         | any good reason someone would have it on hand either.
        
           | smeyer wrote:
           | Have you actually checked your grocery store? Mine sells both
           | iodized and uniodized table salt, in addition to the kosher
           | salt idea that folks have mentioned. I know the OP said that
           | they worried about anti-caking agents in kosher salt and I'm
           | no expert, but I thought they didn't usually have them.
        
           | JoeDaDude wrote:
           | 'twould appear that non-iodized salt is used in cheese
           | making, so maybe salt labeled as cheese making salt might
           | work.
        
           | robocat wrote:
           | Perhaps get a 20kg / 40lb bag of pool salt for $20.
           | 
           | I'm not sure about purity or anti-caking, although some
           | brands are advertised as high purity. You can even get it
           | delivered in the US: https://www.amazon.com/s?k=pool+salt
           | 
           | Perhaps look at the 20kg bags of food salt sold at
           | wholesalers, which might not be iodised. I recall seeing one
           | at a Chinese store, but I'm in New Zealand, so I'm unsure
           | about the US.
        
           | btilly wrote:
           | The article says that iodized table salt doesn't work, and
           | isn't optimistic about kosher salt either.
        
           | nitrogen wrote:
           | If you can get "kosher salt," IIRC that should be non-
           | iodized.
        
           | derobert wrote:
           | If you look for canning / pickling salt, that should be free
           | of both iodine and anti-caking agents.
        
           | outworlder wrote:
           | What about dishwasher salt? It's usually 100% sodium
           | chloride.
        
             | jldugger wrote:
             | I dont think anyone in the US sells that tho.
        
               | unwind wrote:
               | What? Why not?
               | 
               | A quick check of Amazon.com [1] turned up a bunch of US-
               | looking products, at least.
               | 
               | [1]: https://www.amazon.com/s?k=dishwasher+salt&crid=X602
               | 5PAVFBMS...
        
               | jldugger wrote:
               | The only brand I even recognize is Finish, and they're a
               | UK firm, not American. Technology Connections mentions[1]
               | it's a European thing: "I have never ever encountered
               | one, and I don't think I've ever seen dishwasher salt
               | sold in a store."
               | 
               | [1]: https://www.youtube.com/watch?v=Ll6-eGDpimU&t=2098s
        
               | outworlder wrote:
               | > The only brand I even recognize is Finish, and they're
               | a UK firm, not American
               | 
               | Plenty of non-american firms sell products in the US.
               | Like... I don't know, Nestle?
               | 
               | I watched the same Technology Connections video. He does
               | mention Bosch dishwashers by name. Those are available in
               | the US. It's just that people barely bother understanding
               | how dishwashers work, let alone _very infrequently_
               | refilling the salt. Heck, people drive without checking
               | tire pressures, dishwasher salt has no hope.
               | 
               | Not surprising that most stores don't bother. It lasts
               | forever too.
        
             | jsmith45 wrote:
             | Dishwasher salt is not actually widely available in the US,
             | since we we generally don't have dishwashers with built in
             | water softeners that need the salt.
             | 
             | Most places either have soft water from their water supply,
             | or people install a whole house water softener, if their
             | water is hard enough to cause problems with mineralizing on
             | dishes.
             | 
             | The salt for the whole house water softener would probably
             | work, but the bags are pretty huge.
        
               | outworlder wrote:
               | > Dishwasher salt is not actually widely available in the
               | US
               | 
               | I am in the Bay Area. I bought some off Amazon no
               | problem. It came from the US too.
               | 
               | > since we we generally don't have dishwashers with built
               | in water softeners that need the salt.
               | 
               | Landlord installed a Bosch dishwasher, which has a water
               | softener. The water is pretty hard (I can see by the
               | shower faucet, and confirmed on the utility website). I'm
               | assuming he didn't bother to import the dishwasher from
               | Europe so it must be available in the US.
        
         | nitrogen wrote:
         | _I 'm sure most of those "science for kids" book authors never
         | tried a single one of their experiments. _
         | 
         | They should at least recommend distilled water because tap
         | water impurities vary greatly from place to place.
        
       | leoc wrote:
       | Parents! Are your teens getting into "salt"? Know the signs.
        
       | ttoinou wrote:
       | Looks really good. My three chemicals for crystal growing are
       | 
       | ADP
       | 
       | https://en.wikipedia.org/wiki/Ammonium_dihydrogen_phosphate
       | 
       | and MKP
       | 
       | https://en.wikipedia.org/wiki/Monopotassium_phosphate
       | 
       | and Alum
       | 
       | https://en.wikipedia.org/wiki/Potassium_alum
       | 
       | but probably table salt is cheaper..
        
         | mellavora wrote:
         | Careful using Xerox scans to create your posts...
        
         | isoprophlex wrote:
         | Those monopotassium phosphate crystals look gorgeous! Any tips
         | for places to buy that salt?
        
           | ttoinou wrote:
           | 6 years ago on eBay 2 kg for 30 USD from UK to continental
           | Europe. 2 months ago on Amazon 5 Kg for 43 USD delivered in
           | Europe. It's a fertilizer so it's not supposed to be
           | expensive
        
       | k__ wrote:
       | At school we had a sodium crystal that was around 15cm in
       | diameter.
       | 
       | A teacher said, they found it in the woods.
        
       | isoprophlex wrote:
       | When I was an organic chemist, growing crystals was of paramount
       | importance for certain structure determinations using X-ray
       | crystallography (to answer "did I really prepare what I think I
       | prepared?")
       | 
       | With sensitive compounds, sometimes you can't just let things
       | evaporate. Also as the article states, weather conditions might
       | mess you up. IMO the coolest trick we had to solve this was
       | osmosis of an anti-solvent into a saturated solution.
       | 
       | A small sealed container with a saturated solution of your
       | compound/salt is punctured, and put in a bigger sealed container
       | containing a worse but miscible solvent for the compound under
       | study. Slow diffusion into the inner container causes very
       | reproducible crystal growth, as long as you can control the
       | temperature.
        
         | gwerbret wrote:
         | > growing crystals was of paramount importance for certain
         | structure determinations using X-ray crystallography (to answer
         | "did I really prepare what I think I prepared?")
         | 
         | Ahh, X-ray crystallography, a.k.a. the field of modern
         | (bio)chemistry that most closely resembles medieval alchemy.
         | 
         | The excellent 2009 documentary "Naturally Obsessed" [0] is
         | about how difficult, time-consuming, and frankly irrational it
         | can be to successfully crystallize certain proteins and protein
         | complexes. The film is about how some PhD students spend the
         | entire five-ish years of their degree programs trying (and
         | mostly failing) to find the secret recipes (protein
         | purity/additive ingredients/temperature/humidity/phase of the
         | moon) that will allow their proteins to crystallize, and thus
         | granting them data with which to populate their dissertations.
         | 
         | Why irrational? In one case, the secret ingredient is pickle
         | juice.
         | 
         | [0]: https://www.thirteen.org/naturally-obsessed/
        
         | voldacar wrote:
         | That's really clever. How long did this process usually take,
         | what size crystals were you going for? And were these crystals
         | ever visually interesting, or do most organic compounds just
         | form colorless little prisms or cubes?
        
           | isoprophlex wrote:
           | "Sadly" (not for me back then) a crystal 1 mm on a side is
           | more than plenty for structural elucidation. They were only
           | ever pretty to me because
           | 
           | A) you sometimes spend weeks working on the materials that go
           | into the solution, seeing them feels like a "my god finally"
           | kinda thing
           | 
           | B) under a microscope crystals are especially beautiful, even
           | small crystals. We had a microscope set up in an inert
           | atmosphere for sensitive compounds, see eg.
           | 
           | https://www.jacomex.com/wp-
           | content/uploads/2019/08/microscop...
           | 
           | About timing: this could take anywhere from days to months...
           | really dependent on how fast you can go without making ugly
           | intergrown xtals, on how well you select solvents, etc.
           | Experimental science can be cruel.
        
         | andrewla wrote:
         | Neat -- turns out that for sodium chloride there is extensive
         | literature on this. Ethanol is apparently effective as an anti-
         | solvent, but various dimethylisopropylamine compounds appear to
         | be more effective and are used in industrial settings.
         | 
         | Interested now to try this experiment but with ethanol to
         | better control the crystal formation.
        
           | isoprophlex wrote:
           | Wonderful! I was tempted to do some searching on ethanol,
           | acetone, any volatile things that are generally available...
           | good to know ethanol is effective.
           | 
           | Will be a fun xmas experiment to do!
        
       | dekhn wrote:
       | Crystallography, the study of crystals and the structures of
       | their constituents, is fascinating. I work in a field where
       | making crystals like this is so tough that people spend millions
       | of dollars on robots and reagents that just sit around trying
       | every possible combination of temperature, concentration, and
       | other parameters, just to make crystals with high enough quality
       | to do structure determination.
       | 
       | Some crystals just never form. I know folks who spent 7 years
       | trying to get their protein to crystallize and left grad school
       | with a masters degree instead of a PhD because they failed, no
       | fault of their own.
        
       | Turing_Machine wrote:
       | I used to enjoy growing crystals when I was a kid. It's a good
       | indoor activity for the winter.
       | 
       | Plain white sugar is also interesting. Alum (used to make
       | pickles, can often be found in the herb and spice aisle at the
       | store) makes neat crystals.
       | 
       | If your kids are old enough to be trusted not to eat the
       | experiments, copper sulfate (used to kill roots that are growing
       | into sewer lines) makes beautiful crystals. It can be found at
       | Home Depot-type stores.
       | 
       | Edit: I see this author has a link to another article on growing
       | copper sulfate crystals down at the bottom of this article.
       | Recommended!
        
         | jrumbut wrote:
         | I was trying very hard to remember what the other two "classic
         | fun-for-kids crystal growing" chemicals were and it was eating
         | me alive.
         | 
         | Thank you for the answer, I still remember my alum crystals for
         | the grade school science fair.
        
           | Jiro wrote:
           | I tried Epsom salts as a kid, since there was some around the
           | house. They were a lot easier to grow than table salt.
        
             | Turing_Machine wrote:
             | Epsom salts! Yes! Another good one.
        
           | mountain_peak wrote:
           | Alum crystals in a disposable pie pan on a hot water radiator
           | turned out brilliantly in my youth.
           | 
           | Fast-forward many years, and my daughter wasn't having much
           | luck with salt, sugar, or even copper sulfate (that one
           | looked like a melted smurf).
           | 
           | I remembered my alum crystals, which she tried, and lo and
           | behold...nothing! Desperate (on the night before the
           | assignment was due), I remembered someone mentioning that you
           | can make crystals with mothball flakes. We picked a bag of
           | flakes up and heated them up in a dish, and were able to make
           | long, beautiful crystals on the bottom of a cold glass over
           | the heated solution.
           | 
           | The only problem was that as soon as we moved the glass away
           | from the solution, the crystals evaporated, so she took a
           | picture of the crystals as they were forming and received
           | full marks. A happy ending, but the house smelled of
           | mothballs for a few days!
        
         | outworlder wrote:
         | > If your kids are old enough to be trusted not to eat the
         | experiments, copper sulfate (used to kill roots that are
         | growing into sewer lines) makes beautiful crystals. It can be
         | found at Home Depot-type stores.
         | 
         | I had a chemistry set as a kid, it had copper sulfate. The only
         | crystals I've managed to grow :)
        
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