These differences were only noticeable under bright light and on close inspection--indicative of the general irrelevance of the claims on detergent labels.
Using the detergent would leave a noticeable change, but only if you held the item under bright lights and looked at the garment.
mnli hypothesis: Using the detergent would leave a noticeable change, but only if you held the item under bright lights and looked at the garment. premise: These differences were only noticeable under bright light and on close inspection--indicative of the general irrelevance of the claims on detergent labels.