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Hair tests for perming and neutralising

You should always explain the importance of tests to your client so she is aware that you are checking to see whether the hair can withstand the chemical process you are going to carry out.

Elasticity test
This is to test the internal strength of the hair (the cortex). Hair that has been damaged due to chemical treatments may have lost much of its natural strength. This type of hair may stretch over two-thirds of its original length and may even break off. It is important to carry out this test before perming. Hair that is in good condition will stretch and then return to its original length.


Take one strand of hair and hold each end firmly between the thumb and forefinger of each hand and gently pull. If the hair stretches more than half of its original length then it is over elastic and may snap or break during chemical processing.

Porosity test
This tests the condition of the outer layer of the hair shaft – the cuticle. If the cuticle is damaged, it becomes porous. Perming chemicals added to porous hair will be absorbed unevenly and may produce uneven curl results. This is why special perm lotions for tinted and highlighted hair are used. They are weaker in strength and are less likely to over process the hair and give a poor result.


Take a strand of hair and hold it by the points (where the hair has been cut) between the thumb and forefinger of one hand. Run the forefinger and thumb of your other hand from the root (where the hair grows from) down to the point. If the hair feels rough and bumpy, the cuticle scales are raised and open and this is an indication of porous hair. If the hair feels smooth, the cuticle is flat and closed and the hair’s cuticle region is in good condition.

Incompatibility test
Some chemicals do not work well together (they are incompatible) and may have a bad reaction if one is used over the top of another. Some colours, for example, contain metallic salts, which are incompatible with other chemicals. You should carry out an incompatibility test before perming if you are unsure of the colouring products already on the hair or if the hair has a doubtful history.


• Mix together (preferably in a glass bowl) 40 ml of 20 volume hydrogen peroxide and 2 ml of alkaline perm lotion.
• Place a small cutting of hair in the solution and wait. If heat is given off, the lotion fizzes and the hair breaks, dissolves or changes colour, then this is a positive reaction and the hair should NOT be permed or coloured with a product containing hydrogen peroxide. The hair contains metallic salts.

Pre-perm test curl
When handling fragile, porous hair or hair with a doubtful history, it is advisable to
wind, process and neutralise one or more small sections of hair. The results will be a
guide to the best rod size, processing time and lotion strength to use. This test will
also give a good indication of the condition after the perming process and will
determine whether the hair is suitable for this treatment.

It is not always suitable or possible to carry out a test curl on the head, so a cutting of
hair may be taken and tested separately, but remember, there will be no scalp heat to
help the processing.

• Wind two or three rods of your chosen size in the hair.
• Apply perm lotion suitable for hair condition and leave to process for the
manufacturer’s specified time.
• Carry out a development test curl to see whether processing is sufficient. If so,
rinse, neutralise for the time specified by the manufacturer, remove rods and
evaluate curl result.

Development test curl
This test is carried out during the processing of the perm to check whether the
desired development has been reached. Always wear gloves to carry out this test.
• Hold perm rod and undo rubber fastener.
• Unwind the curler one and a half turns or until you see the start of the perm paper, holding firmly.
• Push the hair up and then in towards the scalp, allowing it to relax into an ‘S’ shape movement. Be careful not to pull the hair as it is in a very fragile state.
• When the size of the ‘S’ shape corresponds to the size of the curler, the processing is complete and the hair should be rinsed with warm water to avoid over processing and neutralised following manufacturer’s instructions.

Always take test curls on different areas of the head as one area may be ready before another and this would cause an uneven curl result. The temperature of the salon will make a difference. Perms will process quicker on warm days than on cold days.


Once you have carried out the necessary tests and you are satisfied with the results, continue with the service.

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