As Housekeeping and Professional Laundry Manuals
Pointed out years ago about the over use of bluing (or use of at all) to counter yellowed article after laundering with soap; if the wash was properly done in the first place bluing (nor OBAs for that matter) are necessary.
Yes, cotton textiles yellow with age and bluing/OBAs can help mitigate this to an extent. However much of the yellowing you see with white laundry comes from bad practices such as but not limited to:
Allowing items to become soiled then not sent to the wash at once.
Use of soaps, soda and or other alkaline substances in the wash but failing to rinse properly to remove all residue.
Failure to remove all traces of soap before using certain types of bluing.
The yellowing some of you are seeing after using soap for the wash is no different than what housewives/laundries faced years ago; residue of soap and or alkali reacting to the application of heat from irons or today heated dryers. In addition certain types of bluing contain iron like minerals and will react with soap residue. The result when heated (again by irons or dryers) is yellowing or brown/rust colored marks.
It cannot be stressed enough; if you are using soap for laundering you need hot or warm water for the wash and the same (though hot is better) for at least the first, second or even third rinse, followed by a final cold.
As have said often one of the reasons wash was boiled after using soap in the wash was to liberate any reside before the textile fibers closed in a cool or cold rinse. When washing machines came along (along with indoor plumbing one assumes) it was found several rinses in hot water did the same as boiling. If you did, want or could not boil it was often recommended to either plunge your soapy wash into scalding water or pour the same over. In any event the working theory was clear, the soap had to come out of textiles.
In addition to being hot or boiling these rinse waters had to have soft water. If you rinse soap laden laundry in hard water it will cause the formation of lime curds (scum) that will cling to the fabric.
Anyone who cares to look this up simply search Google books for housekeeping and laundry manuals going back to the early 1900's or even middle to late 1800's.
Those of you blessed to have learned or at least observed someone from the "Old Country" using the old ways of doing laundry with soap know what one is saying.
Or you just could ask "Norge" *LOL*
http://https//books.google.com/book...SJ4qq4DQ&ved=0CFEQ6AEwCDgK#v=onepage&q&f=true