I think biological soap powders are wonderful but not on clothes if you have sensitive skin like mine.
I use them in the kitchen for burnt bakeware especially glass or ceramic ovenware. They work wonders!!!
I always have some supermarket brand biological powder in the cupboard. All I do is put a quarter of a mug full of biological powder into the baked ovenware, fill with hot water and leave it overnight.
In the morning, pour away the water; give it a very gentle scrub; rinse thoroughly in hot water and it should have returned to its former glory.
You can also use the same method for tea stains in mugs etc. Just bear in mind that you will need a smaller amount since the mugs are smaller.
However, a word of caution….. if you have expensive ovenware, I would go easy on the biological powder. For example, I wouldn’t use biological powder on my Le Creuset saucepans and bakeware. I simply dare not!
I have also used biological powder which I made into a thick paste with water to rub over communion wine stains on the Mhinisteir’s Cassock Alb!