I think washing detergent for white fabric can contain bleach, so the clothes will stay white and won’t become grey. If this is the case, it’ll gradually fade any colors of colored fabric.
And the other way around it won’t keep the white perfectly white.
Dunno about the bleach part, that might be in some as well, but typically white fabric detergent contains optical brightener that counters the typical yellow tint of worn garments by emitting extra blue light (and your eyes perceive the full presence of the spectrum as white). That’s also why this whitening effect will fade off if you then use detergent that doesn’t contain brighteners: you are washing out those blue light particles once again.
optical brightener
AKA blue dye.
The process is also called “bluing” and existed way before they made up a scientific “you have to buy this product, you can’t do this at home” name.
Well that unlocked a memory. I was on a road trip around California and stopped off in a small town to do my laundry. An elderly gent was already in the laundromat and the washing machine window showed bright, bright blue. He said he recalled that his late wife used to use blueing tablets to get the sheets etc white. “I couldn’t find any at the store, but these toilet cleaning tablets are blue, so figured I’d try them.”
This is what my late mother used: https://www.retonthenet.co.uk/vintage-washing-laundry-reckitts-bag-blue-reckitt--coleman-hull-dolly-bag-1960s-nos-dolly-blue-5487-p.asp
Optical brighteners aren’t the same thing as blue dye, even though they have the same role. Optical brighteners absorb high wavelength (UV) light and re-emit it as blue light. This helps prevent the new particles from overpowering or covering the existing dye. Blue dye would just paint the clothing more blue, which usually isn’t what you want.
So in this case it isn’t just marketing bla bla for some old thing, it’s actually a new(er) thing that replaced the old thing.
Honestly I’m more in the “buy durable fabrics and treat them well but if they acquire a tint or lose color over time so what” camp. Good linen shirts for instance will still look great after a long time, never mind any fading. For some stuff it can even enhance the optics like the famed worn out jeans look.
Washing white stuff with regular or color detergent is mostly fine, washing dark stuff with detergent for white stuff is not fine.
Stuff formulated for whites specifically CAN contain things like bleach that can fade colors faster. Its not going to do it in 1 wash but cumulatively over time.
If it isn’t specifically for coloured clothes, it contains optical brighteners, which fluoresce under UV light (like the sun) to make whites appear whiter. That’s fine for light colours, but it makes blacks look greyish and dull.
I have literally never separated my clothes, and I’ve never had anything get messed up.
New stuff should definitely be washed on it’s own a couple of times, before being mixed in. New stuff can easily give off enough color to make a white shirt pink for example when washed with a red thing.
Just because you’ve been lucky or maybe have a lot of same colors where it doesn’t matter doesn’t mean it’s a general rule to go by.
Ah right, makes sense. In that case it probably fine to just mix it up. But if you want old whites to pop a bit more, using a detergent for white stuff works well.
Personally I use a special detergent for blacks and darks and also the dark program on the washing machine. I’ve found it greatly increases the life of black and dark stuff. I almost exclusively wear black and dark blues and want to use clothes as long as possible.
No? Why would it only happen in non-cold water?
When the clothes are first colored they use too much dye, because using too little ruins a batch of clothes whilst using too much is only bad for the environment but good for making money. The surplus of dye can’t adhere to the fabric, so the first couple of times you wear/use and or wash the clothes the extra dye comes off.
I had a set of dark green bed sheets give off blue dye onto my white matrass cover. I didn’t wash them together, but the extra dye still came off in use. Obviously water will help the dye become mobile a lot, but it isn’t necessary. I’m not sure if the temperature has any effect at all.
Aside from new clothes bleeding dye, there’s definitely a difference in whites, even if you can only see it in comparison to other whites.
Actually, I think at that point it’s the dryer, scattering fine colored lint across the white shirts, making them appear duller, greyer
