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.
