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How to carry out a skin test

How to carry out a skin test

Postby chris the limey » 22 Oct 2010 02:48 pm

Para dyes are toxic dyes in that they can produce para poisoning in some clients. This para poisoning is known as allergic dermatitis. The symptoms are unpleasant, with itching and a blotchy appearance on the skin of the face and neck. In severe cases, the face becomes so grotesquely swollen that the eyes cannot be opened and the mouth and lips swell to such an extent that swallowing and speaking become difficult. The skin may erupt and 'weep' over the whole of the body. These symptoms are often accompanied by a violent headache, shivering and a high temperature and it may be many months before a full recovery is made.
It is important, therefore, that the skin is tested for a reaction before each application of a para dye, as even a client who has had regular para dyes can still develop an allergic reaction (often called 'becoming sensitised'). A skin test should be carried out 24-48 hours prior to the tint application and although this may often be inconvenient, to both the client and the hairdresser, it is very much a case of 'better safe than sorry'.

Method of applying a skin test

1 Clean a small area, either behind the ear or in the crook of the arm, with surgical spirit.
2 Mix a small amount of a dark shade of the tint to be used (the darker shades
contain more para compound and are, therefore, more likely to produce a reaction) with hydrogen peroxide (as in the manufacturer's instructions).
3 Apply the tint to the clean area, about the size of a one pence piece, and leave it to dry.
4 To protect the area, cover with cotton wool and leave to dry.
5 Leave for 24--48 hours without disturbing.
6 If no irritation occurs, the test is negative and it is safe to proceed with the tint.
7 If irritation does occur, the test is positive and it is dangerous to proceed with the tint.
NB A skin test can also be called a patch test, allergy test, hypersensitivity test, predisposition test, idiosyncrasy test or Sabourand-Rousseau test.
chris the limey
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