Hairdresser Conducted Tests

Prior to undergoing chemical procedures your hair should be examined and exposed to certain test procedures – Is it?

Hairdressers owe their clients a duty of care. As such they are expected to conduct routine tests where available to establish the ability of the skin or hair-shafts to withstand the intended chemical / physical procedure and provide a useful guide to colour attainability.


All forms of chemical hair colorants create irreversible changes and minor damage to the delicate micro-structure of the hair-shaft. This vulnerability may dramatically increase with length, the degree of weathering and any previous chemical processing. All prospective chemical colouring should therefore be approached with caution and preceded with routine tests to skin and hair to establish levels of reactivity, vulnerability and colour effectiveness.


An allergic reaction can potentially follow any exposure to a hair dye or any other product containing:
The reaction can vary from mild itching to severe skin inflammation with oedema and potentially toxaemia.  Such reactions have been known to occur suddenly in individuals with long histories of trouble-free exposure to hair dyes. As potential vulnerability exists in everyone and at any time, the product manufacturers recommend that an allergic reaction test should precede each and every application.  This test involves exposing the skin (at sensitive regions) to the dye for a period of 48 hours prior to the application. Any evidence of erythema, pruritis or oedema during that time will be indicative of an allergic reaction and demand the abandonment of the procedure.


Each should be preceded by compatibility testing (strands testing) – a process designed to establish the compatibility of the products to be used with the individual’s hair. The procedure involves subjecting small groups of the individual’s full-length hair-shafts to the full process in advance. Any unexpected response will provide the opportunity to cancel the procedure.


Realistic visual / manual examination by the hairdresser to note the general status of the scalp and hair and any obvious areas of vulnerability to the intended procedure.

Elasticity, recoil and severance testing may be conducted by stretching single hair-shafts.  This is performed by grasping the hair-shaft firmly between the nails of the thumb and forefinger of one hand as an anchor point whilst allowing the other hand also gripping the hair-shaft similarly to slide along it in the opposite direction causing a significant drag effect to gently stretch it.  Any undue severance could be a reason for reconsidering the procedure. The hair which remains intact will when released exhibit a degree of the recoil. A low level of recoil will suggest poor elasticity which may influence a decision to proceed with certain chemical processing. 

Contact Reaction Testing (to determine the skin’s reaction to bleach).

This ‘Patch Test’ provides a valuable assessment of contact reaction vulnerability to colouring / decolouring products containing hydrogen peroxide which can potentially cause burns / blistering.  Vulnerability to bleaching compounds can vary in any individual from day to day.  Reaction would be influenced by the absence or presence of levels of natural skin grease (a barrier) potentially influenced by grooming products used, the potency of the chemicals to be applied and the period of exposure to them. Testing of the skin’s reaction should be conducted on the actual day prior to the intended procedure and be monitored throughout the exposure time given.