Why is a patch test required before every use, and how do I do it properly?

Even if you have used this or similar dyes before without issues, sensitization can develop at any time. The patch test detects a delayed contact allergy (type IV hypersensitivity) that may not appear on first exposure. Mix a pea-sized amount of color cream with an equal amount of developer. Apply a small dab (about 1 cm diameter) on the inner forearm or behind the ear — areas with thin skin similar to the eye area. Leave uncovered and do not wash for 48 hours.

Watch for redness, itching, swelling, burning, blistering, or any skin change at the test site. Also monitor for systemic signs like eye swelling, nasal congestion, or difficulty breathing. If any reaction occurs, wash the area immediately and do not use the product. A negative test does not guarantee zero risk, but it significantly reduces the chance of a severe reaction during full application. Keep the test mixture covered if you plan to use the same batch, but do not store mixed dye — prepare fresh for the actual application.