Hair colour formulas: how to record them so the colour always comes out the same

“I want exactly the same as last time.” The most common phrase in a salon, and the most dangerous when last time was two months ago, a colleague did it and the formula was on a scrap of paper next to the basin. A colour that wasn’t recorded doesn’t get repeated — it gets reinvented.

What a complete formula includes

• Brand and range — one manufacturer’s 7.1 is not another’s 7.1.
• Shade or mix of shades with quantities: e.g. 30 g 7.1 + 10 g 8.0.
• Developer: volume or percentage (20 vol / 6%) and mixing ratio (1:1, 1:1.5).
• Processing time and whether heat was used.
• Where it was applied: roots only, roots and lengths, highlights, balayage.

The starting point matters as much as the formula

The same formula gives a different result on a natural level 6 and on a level 6 with leftover old colour. Record the natural base, percentage of grey, condition of the hair and previous chemical treatments — colour removal, straightening, perms. These explain why a colour “grabbed” differently.

Result and photo

One line on how it turned out — “slightly warm on the lengths, next time +5 g 7.1” — and before and after photos in the same light. The photo shows a colleague what the client means by “the same”, and settles any argument over whether the colour “was lighter last time”.

Skin tests and reactions

Colour manufacturers recommend a skin sensitivity test before every oxidative colour, especially for new clients or after a long gap. Record when it was done and the result, and any reaction — itching, redness, sensitivity to a product — somewhere prominent on the record card, not buried in the notes.

When to write the formula down

While the colour is processing — not at the end of the day. Your gloves are stained and the pen is out of reach, which is why dictation is the most realistic option: you say the formula out loud and it goes straight onto the client’s record.

In HairPro every colour is logged on the record card with its date — shade, developer, ratio and time — together with photos, and you can dictate it while the colour is processing. Next time you’ll find it before the client has even sat down.

Conclusion

Brand, shades in grams, developer, ratio, time, starting point, photo and skin test. With these, “the same as last time” stops being a gamble and becomes a promise the whole salon can keep.