This product is sold and described as an anti-dandruff mask, so visible flakes are one of the issues it is meant to address alongside oiliness. The key ingredients for this are tar and ichthyol. Tar is used in hair and scalp cosmetics to help reduce the look of excess oil and visible flaking. Ichthyol has soothing properties and appears in products aimed at scalp balance. The Sebo-stop complex is focused on oily scalp concerns and weakened-looking hair, helping to improve the condition of the scalp surface and support the hair along its length.
The intended effect is that less visible oil and buildup at the roots can make flakes less obvious, while the hair stays lighter and easier to manage without harsh stripping. The mask is not meant to replace a medical treatment. If you have persistent, worsening, or painful flaking, or if the skin is red or very uncomfortable, speak to a specialist instead of assuming a cosmetic mask is enough.
As with any active scalp cosmetic, results can vary from person to person. Using the mask as part of a regular washing routine gives it a fair chance to work, but a single use is unlikely to change the scalp noticeably.