Always seek professional advice before colouring Human Hair.
Temporary or semi permanent colour can be used on human hair but care must always be taken where the weft is machined, as bleach products or even water can eventually rot the cotton thread with which it is sewn.
Wefts are made with cotton thread as it is the best thing to hold the hair in place and prevent the hair from slipping and working its way out of the weft. When the thread is wet it stretches slightly so therefore makes the weft very vulnerable and hair loss can occur at this stage. Never comb a weft when it is wet. Just detangle it with your fingers. Always hold the top of the weft securely.
It is a lot easier to make a colour darker than it is to lighten. To lighten a darker colour means you have to first bleach it and then colour it. Such a treatment does not guarantee 100% transformation into the colour you need with a very high risk that the bleach could turn it into orange.
With temporary colour or some semi permanent colours you can only add colour but you can not lighten the shade with it. This means that with colours 1B, 2, 4 etc you cannot make them lighter.
It is always easier to add colour than it is to lift it out to lighten the shade of very dark hair. The natural red pigment which comes through when bleached is hard to lift and dark hair can become orange. Another bleaching process would be required but the hair can loose its natural lustre and become hard and brittle like straw.
The permanent colouring of human hair can be a very tricky process and should always only be attempted by a professional hairdresser, who is experienced in the art of colouring. Even then the hair itself determines the final colour result.
A strand test should therefore always be done before attempting any type of colour, to asses the final result and reaction of the product on the hair.
In the case of bleaching or permanent tinting, if the hair becomes brittle and breaks easily then the colour should not be applied. If the hair looks like cotton wool, the chemicals have burnt it and again it should not be applied.
Human hair can vary vastly in strength and texture from one head to another and from one nation to another. Outside influences can affect hair such as ultra violet exposure from the sun’s rays. Over exposure from sea and wind and many, many more things such as ill health, diet good or bad, or the taking of any medication, even a simple aspirin.
Some people have very strong hair that will withstand lots of chemical processes that occur in permanent hair colouring. Whilst others have much finer hair which is therefore more fragile and much weaker. This type of hair can be very porous and absorbs colour very quickly but can become damaged with some chemical processes.
Whilst the very strong hair is more resistant to the chemical processes performed in bleaching to lift out and lighten the natural hair colour it is also more difficult to lighten. To add colour or permanently tint the same strong human hair, it takes much stronger chemicals first to lift the natural colour and then add the desired tone of the permanent shade.
The above is a fair and frank expert opinion based on decades of experience in this line of business. They are the issues and concerns we have and would like to highlight them to you at the outset.