NaillyTop coat is the clear final layer sealed over colour and art — and it is where more of a manicure's character lives than most people realise. Durability lives there: the top coat takes the scratches, the dishwater and the keyboard so the colour underneath does not. Finish lives there too: the same red becomes classic under gloss and velvet under a matte top coat, and chrome or glazed powders are locked in place by the seal above them.
In gel systems the top coat cures glass-hard and lasts the life of the set; a quick layer of ordinary clear top coat later in a set's life is also a legitimate field dressing for a small chip. If a design decision feels invisible, it is probably a top coat decision — and it is worth making out loud at the salon.