Whites turning yellow

Discussion in 'Chemistry' started by paulfr, Oct 7, 2009.

  1. paulfr Registered Senior Member

    Messages:
    227
    I live in Thailand and cannot figure out why my whites and
    underwear keep turning yellow.

    This is very frustrating.

    I assume it is the wash.
    We use non bleach detergent.
    Underwear from Land's End says material is cotton/baumwolle,
    not 100% cotton.

    The water, type of detergent, the material ...... what ?

    And how can I keep my whites white ?

    Thanks
     
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  3. John99 Banned Banned

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    22,046
    'We use non bleach detergent.'

    that is the problem.
     
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  5. paulfr Registered Senior Member

    Messages:
    227
    But the clothing tag instructions say

    "Do not use clorine bleach"

    Are there other kinds of bleach ?


    And I would like to understand the chemistry here.
    Is the yellow salts or oxides or what.
    And why do they get that way ?

    Curious about the Chemistry around the house
    in addition to the frustration of my clothes
    not looking right.
     
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  7. nietzschefan Thread Killer Valued Senior Member

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    7,721
    Are the labels in Engrish now too?
     
  8. paulfr Registered Senior Member

    Messages:
    227
    Well I bought this underwear from Land's End because
    Thailand does not have the large sizes that many Farang [Westerners]
    need. So yes the labels are in English.

    English is taught [only one hour per week] in all the Thai schools in recognition
    that it is the lingua franca of world business. But the resulting fluency is very low.
    The International schools, however, are all English in both teaching and among
    the student to student conversations. Many parents here, who can afford the costs
    [10-20K$/yr], want their children fluent in English.

    So what is the chemical compound that accounts for the yellow in whites
    after several washings ? And how does one avoid it ?
     
  9. Trippy ALEA IACTA EST Staff Member

    Messages:
    10,890
    My recollection is that the yellowing of white material occurs because sunlight breaks down the molecules that absorb the blue/ultra violet end of the spectrum.

    The break down occurs by virtue of the fact that the photons at this end of the spectrum are of high energy, and the molecules absorb them, if they didn't, then the whites wouldn't be white.

    My recollection is that there is no way to avoid this breakdown (apart from manufacturing 'sturdier' dies), however it is possible to conceal it by consistently washing in powders that contain stilbene's, or related compounds. These compounds are called 'Flourescent Whitening Agents' and are one of the key indicators of faecal contamination of water. Essentially, they make 'whites whiter, and brights brighter' by absorbing in the UV end of the spectrum, and re-emitting the light (flourescing) in the blue end of the visible spectrum. The increased flux of light at the blue end of the spectrum counters the yellow, making the material appear white. It works on other colours as well, because all colours (except, obviously Blue-indigo-violet) must absorb some, or all of the blue end of the spectrum (and the UV), and so all dyes must fade with time by the breakdown of certain (or parts of) the dye molecules, and the stilbenes counteract this.

    In short, there is no way to avoid the breakdown, but the yellowing can be avoided, or at least slowed by using laundry powders that contain FWA's, which are usually advertised as making whites whiter and brights bighter.

    It should be noted that AFAIR this process is irreversible, so switching laundry powder brands, and washing yellowed whites in it several times probably won't lessen the yellowing.
     
  10. Grim_Reaper I Am Death Destroyer of Worlds Registered Senior Member

    Messages:
    1,349
    It could be what is stated above or just too much curry as well eat a lot of curry it leaks out when you sweat turning your clothes Yellow Or you are washing your clothes in sulfer water or the river you are washing in is very very dirty.
     
  11. spidergoat Valued Senior Member

    Messages:
    51,726
    "baumwolle" is German for cotton.
     
  12. candy Registered Senior Member

    Messages:
    734
    If you want your whites white use a bluing rinse and hang them to dry in full sun. Avoid using a clothes dryer as much as possible to lessen yellowing.
     
  13. spidergoat Valued Senior Member

    Messages:
    51,726
    Don't wear white.
     
  14. John99 Banned Banned

    Messages:
    22,046
    you can also try seawater.

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