Sorry for the confusion.. The last part of my comment refers to the way a spraying a coating of clear sealer over your finished artwork brightens up the acrylic colors.
As for using water with acrylics.. I never thin my acrylics with water, I always use a acrylic medium to thin them.
I do not know which type of acrylic paint you use, but, there are two types of tubed acrylics available.. Student and Artists... I would never use the Student type, they are usually very poor quality. If that is what you are using, then I would recommend changing to the Artist's type.
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