Originally Posted by catray
Reading all the different colors that bleed makes me think. We live in an area that has alot of minerals in the water. We don't have a water softner except on our drinking water usage. Every part of the country has some problems even though the water you have is not tainted with mineral and such. Could that be part of the problem of one person having one color bleed and not another? Just a thought.
Yes.
The detergent used can also make a difference. Some detergents are so alkaline that they raise the pH of the wash water over 10, which is the point at which even fibre reactive dye molecules will become unattached from the receptor sites on the cotton fibres.
This is an unintended consequence of energy conservation efforts. Many washing machines made in the last 10-15 years no longer have a truly hot wash; they mix in cold water even when set to "hot" because it improves the energy rating assigned. Plus, many people keep their water heaters set at 120 degrees F, which is actually not really all that hot. Combine those two factors and many home washing machines don't really have a wash temp that gets much above barely warm.
Well, on the molecular level, soap and detergents work best in the range between 145 and 200 degrees F. That's way hotter than most domestic washing machines ever get. People don't like it when their clothes don't smell or look clean after going through the washing machine (which is pretty reasonable) so detergent manufacturers had to Do Something.
The use of phosphates in detergents have been restricted in this country because they act as fertilisers in the waterways. Hello algae blooms and mass fish kills! Unfortunately, the easiest way to improve cool and warm water performance of detergents is to add phosphates.
So, manufacturers resort to adding ingredients to make the detergent more alkaline. This isn't shady or necessarily bad; for instance, washing soda is a long used, tried and true way of boosting the power of detergents. But combining a super alkaline detergent with an alkaline water source and trouble with fabrics bleeding can result.
If I had more than a very, very occasional fabric that bled, I'd use my pH strips to check the pH of my water supply and whatever detergents and additives I was using to wash my fabric in and make choices accordingly.
All soaps and detergents are alkaline, it's the nature of the beast. If you add an acid, like vinegar, you also cut the washing power. This probably isn't a problem if you are washing lightly soiled fabric or prewashing new fabrics before use. It will be a problem if you have something that really needs to have dirt, oil or stains removed.
Strictly in my own opinion, I feel the best course is to use a detergent that is as close to neutral as possible. The three products I know of that are closest to neutral pH are Orvus (and the knockoffs like Horvus), Synthrapol and Dharma Professional Textile Detergent.
Finally, a note about colour catchers: they not only catch dye, they also catch tiny bits of lint. Sometimes the colour change observed after washing a brand new fabric is actually due to lint, particularly if it is a fabric with a very soft, almost velvety texture. Cotton fabric woven with mercerised threads are smoother and more lustrous with deeper colours but they're also more expensive. Cotton fabric woven with unmercerised threads has an ever so slightly more velvety texture, with no lustre and they also shed more lint.