# Use By Date- Salt **URL:** \ **Category:** Factual Questions\ **Created:** [February 7, 2008, 12:23pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663 "2008-02-07T12:23:34Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Cicero](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cicero/32/3594_2.png) [@Cicero](https://boards.straightdope.com/u/Cicero)\ **Post date:** [February 7, 2008, 12:23pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/1 "2008-02-07T12:23:34Z")
This could easily go in MPSIMS. But I have a bottle of rock salt (with attached grinder) which has a use by date of 2002. As far as I know salt is a naturally occuring substance which cn sit in the sea (or Siberian mines) for thousands of years. Why a use by date? ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [February 7, 2008, 12:26pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/2 "2008-02-07T12:26:57Z")
Because it’s a “food product” as defined by whatever law covers these things, and food products have to have use-by dates. AFAIK, the longest shelf life a food can legally have is 3 years, regardless of how many millennia it has been lying around before being put in a packet. In other words, ignore it and enjoy your lovely salt. ---
**Author:** ![A.R.Cane](https://avatars.discourse-cdn.com/v4/letter/a/ee7513/32.png) [@A.R.Cane](https://boards.straightdope.com/u/A.R.Cane)\ **Post date:** [February 7, 2008, 12:40pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/3 "2008-02-07T12:40:00Z")
> [@](#): > > \> “Sell By” Date > A calendar date on the packaging of a food product that indicates the last day the product can be sold. > > > [@](#): > > > > \> “Use By” Date > > This is the last date a consumer is recommended to use a product while it is at peak quality. This date is recommended for best flavor or quality. It is not a “sell by” or food safety date. (Also see “Best If Used By,” Expiration, and “Sell By” Dates.) > > The “sell by” date tells the retailer how long to display a product. It guides the rotation of shelf stock and allows time for the product to be stored and used at home. The date is quality driven, not a food safety concern. (Also see “Best If Used By,” Expiration, and “Use By” Dates.) From here: [http://www.cfsan.fda.gov/~dms/a2z-uvw.html](http://www.cfsan.fda.gov/~dms/a2z-uvw.html) ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [February 7, 2008, 1:13pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/4 "2008-02-07T13:13:14Z")
I have a similar story. An auto mechanic once told me the copper wires in my car would need to be replaced “because they’re old.” I asked if they were faulty or broken, and he said, “No, they’re just old. Haven’t been replaced since the car was made.” I said, “Are you saying that _the copper itself_ is old?” “Yep.” Never mind that copper is an element, formed in the heart of a star billions of years ago, that coalesced into the earth’s crust 4.5 billion years ago. The problem is, this car is _ten years old._ Sailboat ---
**Author:** ![Desultourist](https://avatars.discourse-cdn.com/v4/letter/d/bbe5ce/32.png) [@Desultourist](https://boards.straightdope.com/u/Desultourist)\ **Post date:** [February 7, 2008, 2:48pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/5 "2008-02-07T14:48:49Z")
Without a date, customers could reasonably expect that a product doesn’t degrade over time. Salt remains salt, but it collects moisture from the air. (It’s a different case with copper, of course. The common lesser Car Mechanic possesses a basilisk-like gaze that causes any material to instantly degrade when they set their eyes upon it. This curse can only be lifted by paying the priests of the nearest car temple to cast a spell of Greater Restoration.) So when the salt has gotten soggy years after its purchase (or when the grinder clogs up or rusts because of it), someone might get the idea to sue the manufacturer for selling them an inferior food product. (Or for false advertising, when it was clearly promised that “when it rains it pours”, for example.) With a date, their behinds are covered. ---
**Author:** ![OtakuLoki](https://avatars.discourse-cdn.com/v4/letter/o/ac8455/32.png) [@OtakuLoki](https://boards.straightdope.com/u/OtakuLoki)\ **Post date:** [February 7, 2008, 3:06pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/6 "2008-02-07T15:06:43Z")
It’s not just food products that have unusual expiration dates: most reagent grade chemicals also come with an expiration date. For many of the chemicals this is a reasonable concern - atmospheric exposure, or simple age, may make the chemical non-reactive, or hydrated, or otherwise degraded. But, it’s still a bit shocking to see an expiration date on sodium chloride. ---
**Author:** ![iwakura43](https://avatars.discourse-cdn.com/v4/letter/i/9de0a6/32.png) [@iwakura43](https://boards.straightdope.com/u/iwakura43)\ **Post date:** [February 7, 2008, 3:37pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/7 "2008-02-07T15:37:31Z")
[QUOTE=Colophon] AFAIK, the longest shelf life a food can legally have is 3 years, regardless of how many millennia it has been lying around before being put in a packet. [/QUOTE] FWIW I have beer with an expiration date five years after the purchase date. ---
**Author:** ![Keeve](https://avatars.discourse-cdn.com/v4/letter/k/f07891/32.png) [@Keeve](https://boards.straightdope.com/u/Keeve)\ **Post date:** [February 7, 2008, 3:55pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/8 "2008-02-07T15:55:31Z")
[QUOTE=Desultourist] The common lesser Car Mechanic possesses a basilisk-like gaze that causes any material to instantly degrade when they set their eyes upon it. This curse can only be lifted by paying the priests of the nearest car temple to cast a spell of Greater Restoration.). [/QUOTE] Interesting. My experience, and that of many of my fellow Computer Mechanics is quite the opposite. Whenever one of my clients complains of a misbehaving pc, I stand over his/her shoulder and ask, “Show me what’s wrong.” But the pc sees me, and immediately decides to behave. Result is a wasted service call. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [February 7, 2008, 4:22pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/9 "2008-02-07T16:22:34Z")
[QUOTE=Sailboat] I have a similar story. An auto mechanic once told me the copper wires in my car would need to be replaced “because they’re old.” [/QUOTE] I’ll wager he was referring to your ignition wires, and not all of the regular wiring in the car. Ignition wires do go bad with age as the insulation degrades, and ten years is a good long life for those things. ---
**Author:** ![mnemosyne](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mnemosyne](https://boards.straightdope.com/u/mnemosyne)\ **Post date:** [February 7, 2008, 10:56pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/10 "2008-02-07T22:56:36Z")
[QUOTE=OtakuLoki] But, it’s still a bit shocking to see an expiration date on sodium chloride. [/QUOTE] [hijack] This made me think of something that happened at my former job. The Health and Safety Committee decided (long overdue) to have all the pharmaceutical products (raw materials, APIs) and reagents listed by category (1= less toxic, 4= most toxic), so that employees could know what they were dealing with and the company could enforce proper PPE, etc. A very good idea, particularly with the drugs (I mean, I saw some new female chemists handle testosterone API without any PPE other than lab coats!) Anyways, as you can imagine, this took forever, and so to play it safe until the available data was analysed and complied and the chemical was categorised, H&S decided to declare all unknowns to be treated as Category 4. Sounds good for the API for a new drug product, still in development. Looks incredibly silly when you look at the list and see: Sodium Chloride: 4 Potassium Phosphate: 4 HPLC Grade Water: 4 [/hijack] ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [February 7, 2008, 11:40pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/11 "2008-02-07T23:40:13Z")
[QUOTE=Colophon] Because it’s a “food product” as defined by whatever law covers these things, and food products have to have use-by dates. AFAIK, the longest shelf life a food can legally have is 3 years, regardless of how many millennia it has been lying around before being put in a packet. In other words, ignore it and enjoy your lovely salt. [/QUOTE] Provide a citation to a law or regulation that requires this, please. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [February 7, 2008, 11:44pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/12 "2008-02-07T23:44:17Z")
[QUOTE=mnemosyne] Looks incredibly silly when you look at the list and see: Sodium Chloride: 4 Potassium Phosphate: 4 HPLC Grade Water: 4 [/QUOTE] Well, that ultra-pure water is a pretty strong solvent. It can dissolve solid rock (over decades or centuries) and people almost always die from full-body immersive contact for more than about four minutes, so it deserves that ‘4’ rating. 😛 ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [February 8, 2008, 12:24am UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/13 "2008-02-08T00:24:53Z")
[QUOTE=Sailboat] I have a similar story. An auto mechanic once told me the copper wires in my car would need to be replaced “because they’re old.” [/QUOTE] Spark plug wires DO wear out. Most modern plug wires are not copper core, they are a reistive material, often conductive plastic. If the core is copper, then it is only the insulation that breaks down over time and exposure to oil, heat, road **salt** (HA, thought I was off topic didn’t ya!) etc. Replacing plug wires at 10 years is not an unreasonable preventive maintainance measure. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [February 8, 2008, 2:02am UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/14 "2008-02-08T02:02:39Z")
Salt will never “go bad”, but it could cake up, I suppose. ---
**Author:** ![j666](https://avatars.discourse-cdn.com/v4/letter/j/9de0a6/32.png) [@j666](https://boards.straightdope.com/u/j666)\ **Post date:** [February 8, 2008, 2:04am UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/15 "2008-02-08T02:04:09Z")
[QUOTE=mnemosyne] [hijack] The Health and Safety Committee decided (long overdue) to have all the pharmaceutical products (raw materials, APIs) and reagents listed by category (1= less toxic, 4= most toxic), … Anyways, **as you can imagine, this took forever** , and so to play it safe until the available data was analysed and complied and the chemical was categorised, H&S decided to declare all unknowns to be treated as Category 4. Sodium Chloride: 4 Potassium Phosphate: 4 HPLC Grade Water: 4 [/hijack] [/QUOTE] Actually, no, I don’t get this. There was a Master List of all reagents, and MSDSs on file. Those MSDSs had **NFPA** ratings; the hard copies should have had the rating high-lighted. The reagents should have been classified in ascending order of the Health Rating. What did management decide to do? Classify them in alphabetical order? Oh, for the OP: the manufacturer’s probably based the ‘Use by’ date on stability data for the container. ---
**Author:** ![asterion](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@asterion](https://boards.straightdope.com/u/asterion)\ **Post date:** [February 8, 2008, 2:30am UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/16 "2008-02-08T02:30:19Z")
[QUOTE=mnemosyne] [hijack] This made me think of something that happened at my former job. The Health and Safety Committee decided (long overdue) to have all the pharmaceutical products (raw materials, APIs) and reagents listed by category (1= less toxic, 4= most toxic), so that employees could know what they were dealing with and the company could enforce proper PPE, etc. A very good idea, particularly with the drugs (I mean, I saw some new female chemists handle testosterone API without any PPE other than lab coats!) Anyways, as you can imagine, this took forever, and so to play it safe until the available data was analysed and complied and the chemical was categorised, H&S decided to declare all unknowns to be treated as Category 4. Sounds good for the API for a new drug product, still in development. Looks incredibly silly when you look at the list and see: Sodium Chloride: 4 Potassium Phosphate: 4 HPLC Grade Water: 4 [/hijack] [/QUOTE] Another story of safety people coming up with ideas that they don’t fully think through: Another lab had bought some food-grade sodium chloride. (Not sure why, I assume it was cheap and they just needed brine for aqueous workups.) Anyway, you generally don’t go through that much salt even if you are doing a lot of workups. So of course this bottle of salt had an expiration date on it. Safety apparently threw a fit and demanded that the bottle be discarded because it was past the expiration date. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [February 8, 2008, 3:06am UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/17 "2008-02-08T03:06:31Z")
" if the salt has lost its savour, wherewith shall it be seasoned? " I’m informed that it really does happen. In those salt mines, the salt exposed to the air loses its flavour, cut it away and you’ll find salty salt underneath. cite: [http://www.bartleby.com/81/14806.html](http://www.bartleby.com/81/14806.html) So, once you extract that salt and grind it up into powder it begins to degrade. I’m sure QED or Collibri wil be along soon to explain the science behind it. ---
**Author:** ![A.R.Cane](https://avatars.discourse-cdn.com/v4/letter/a/ee7513/32.png) [@A.R.Cane](https://boards.straightdope.com/u/A.R.Cane)\ **Post date:** [February 8, 2008, 5:41am UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/18 "2008-02-08T05:41:56Z")
I think I may have found the answer. Most table salt contains potassium iodide, which will degrade under some circumstances, include long time storage. Since the FDA bases shelf life on quality (not safety) it makes sense. Here’s a cite: [http://www.saltinstitute.org/iodide.html](http://www.saltinstitute.org/iodide.html) ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [February 8, 2008, 2:19pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/19 "2008-02-08T14:19:52Z")
[QUOTE=Peter Morris] " if the salt has lost its savour, wherewith shall it be seasoned? " I’m informed that it really does happen. In those salt mines, the salt exposed to the air loses its flavour, cut it away and you’ll find salty salt underneath. cite: [Authors - Collection at Bartleby.com](http://www.bartleby.com/81/14806.html) So, once you extract that salt and grind it up into powder it begins to degrade. I’m sure QED or Collibri wil be along soon to explain the science behind it. [/QUOTE] I’ve never heard of this personally, and as far as I know as long as salt remains salt it will continue to taste salty. Sodium chloride is pretty stable. Regarding the quote, the only thing I can think of is that the deposit in question actually mainly consisted of some other compound, and the sodium chloride was washed out of it. If it were or almost pure sodium chloride, it would simply dissolve, not remain in place and “lose its savour.” ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [February 8, 2008, 2:24pm UTC](https://boards.straightdope.com/t/use-by-date-salt/436663/20 "2008-02-08T14:24:20Z")
[QUOTE=Colibri] Regarding the quote, the only thing I can think of is that the deposit in question actually mainly consisted of some other compound, and the sodium chloride was washed out of it. If it were or almost pure sodium chloride, it would simply dissolve, not remain in place and “lose its savour.” [/QUOTE] Some things can wash the savour from salt while it remains in situ: underground rivers, for one. [Next page](https://boards.straightdope.com/t/use-by-date-salt/436663.md?page=2)