Short answer
UK salons must perform a skin test, also called a patch test, at least 48 hours before colouring services to identify reactions to chemicals like PPD. Insurers require these tests to maintain valid public liability insurance, and you must follow manufacturer guidelines and keep accurate, dated records for every client.
Manufacturer guidelines and insurance rules
There's no single UK statute that dictates how and when to patch test, but you have a legal duty of care to protect your clients. In practice, the rules are set by your colour manufacturer and your insurance company. If you don't follow the manufacturer's instructions for the specific colour brand you use, your public liability insurance is invalid.
Most manufacturers require a new patch test if the client is new to your salon, if they haven't had a colour service with you in the last twelve months, or if their health has changed. This includes getting a new tattoo, semi-permanent makeup, or experiencing a severe allergic reaction to any other substance. Always check your specific policy terms with your insurer and consult your product's manufacturer guidelines to ensure you're fully covered.
The 48-hour rule and pre-screening
A skin test must be completed at least 48 hours before the colour appointment. Allergic reactions to paraphenylene diamine (PPD), the chemical found in most permanent hair dyes, are delayed hypersensitivity reactions. Because it's a delayed reaction, starting a colour service before the 48-hour window has passed puts your client at risk, as a reaction won't show up immediately.
Alongside the physical test, you should run a pre-screening health check before every colour service. This is a short list of questions about their skin health and recent changes. If a client answers yes to having a sensitive or damaged scalp, or if they have had any new black henna tattoos since their last colour, you must halt the service and run a new skin test.
Keeping digital records for proof
If a client has an adverse reaction to a hair dye, the first thing your insurer asks for is your record of their patch test. Under insurance audits, "we always patch test" is not a valid defence. If you can't produce a dated record showing the client's consent and the test date, you don't have a defence.
Paper records are easy to lose, and notes in the margin of last year's paper diary end up in the bin. A proper record needs the client's name, the date of the test, the product used, and the stylist's confirmation of a clear result. Luminate helps you track and manage skin tests by flagging overdue tests on your calendar and linking completed digital records directly to each customer profile.
What this means for your salon
To protect your business and your clients, you must establish a clear testing policy that matches your insurer's terms and your brand's guidelines. Never cut corners on the 48-hour waiting period, and make sure every single test is recorded digitally so you can produce proof instantly if an insurer asks.