Too soon for TCA Peel.
Anything stronger than 2 coats 8-9% should be done by a Specialist. Its way too soon to try another peel at day 4, esp. with 15%, even with our 8% we space the peels 14 days apart. Wait 7 days then retry with a single coat, pre acetone scrub- don't burn your self. CheersDr Davin lim Brisbane Australia.