Sodium Perborate
Was the "Per" behind Persil and like the rest of "active" soap and later detergent powders used for washing sodium perborate is the "colour safe" bleach. That is the stuff requires temps of 140F or higher to really get going bleaching wise. Since few if anyone would be washing colours at boil wash temps, there you are then. Same thing with colour safe bleaches like the original "Clorox II"
With the development of oxygen bleach activators (TAED in Europe and NBOS in America) perborate or percarbonate bleaches became active at lower temps and thus the bleaching action started soon after temps reached >86F, therefore colours likely could be affected. Hence the need for detergent just for such items that di not contain bleaching agents.
Sodium perborate is in the cross hairs of EU regulators because of the damage borates cause to aquatic systems. If you notice many detergents on both sides of the pond have switched to sodium percarbonate. You'll also see many products making claims they are friendly to the environment as they do not contain borates.
Sodium percarbonte is known as the "cold water" oxygen bleach since unlike sodium perborate it does work in warm, cool or even cold water. It may take longer to achieve the desired results, but never the lass. In fact it could be argued activators aren't necessary with percarbonate bleaches, but there is a method to the madness.
In water activated (TAED) oxygen bleaches become Peracetic acid which is a more powerful bleach and antimicrobial than hydrogen peroxide. Peracetic acid is recognized in both the EU and North America as a powerful disinfectant. It is what brewers use to sanitize bottles before using them for beer. However the stuff is very unstable in pure form (it only comes as a liquid IIRC) and IIRC slightly dangerous. Activated oxygen bleach OTOH is far more stable for transport, shelf life, etc...
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