Sugar Baby will only deposit visible colour on hair that is light enough to reflect the pink pigment — typically level 9–10 or lighter. Previously permanently coloured hair that sits at a darker level (6–8) may pick up a barely noticeable warm sheen in direct sunlight, but you won't see a pastel pink tone. Highlighted or balayaged sections that reach level 9+ will take the colour, creating a subtle pink accent on those strands while the darker base remains unchanged. This can be a nice low-commitment way to add dimension without bleaching further.
Staining prevention is practical, not optional. Direct dyes transfer via moisture: sweat, rain, damp pillowcases, wet hair against a collar. After the initial rinse and dry, the risk drops dramatically, but for the first 24–48 hours take precautions. Sleep on a dark or old pillowcase, avoid light-coloured hats or scarves while hair is damp, and keep a microfibre towel handy for post-gym sweat. If pigment does get on skin, remove it quickly with an oil-based cleanser or micellar water — water alone often smears it. On fabric, rinse immediately in cold water and treat with a stain remover before washing; heat from a dryer can set the stain permanently.