Colouring the hair is an expensive proposition and the most popular options are permanent colours, as they last for a much longer time. Products like temporary or semi-permanent colours are available as a part of a consumer range, which are available in drug stores or grocery shops.

Salons and professionals use a professional range of products, which can't be bought in stores but are part of a 'service'. Though the same brands or product manufacturers make the consumer range and the professional range. The basic difference between the two is that the number of shades available in the professional range would be as much as five times from the consumer range. It's a much wider choice. Secondly, the consumer range is made in such a way that it is fail-safe. If you go wrong like when you keep the colour on for too long or the application method is not right, it will not cause any damage to the hair.

Temporary colours

These colours come in the form of a mousse, hair spray, or even mascara. They're usually water-based, and are applied to pre-shampooed wet hair. They work by coating the outside or the cuticle layer of the hair. The colour washes out in one or two shampoos. Most of these products are available in chemist shops, grocery shops and supermarkets.

Semi-permanent colours
Semi permanent colours leave the hair shiny. However, they need to be constantly touched up, which make them a more expensive proposition in the long run. These colourants last for up to eight shampoos. And are single solution products that don't require mixing. They enrich or darken hair colour, and can't make it lighter. These colours penetrate the cuticle and coat the outer edge of the cortex. The colour fades gradually, and is ideal for people, who just want to try a different hair colour for a change. It's also good for covering grey hair. Some semi-permanent colours penetrate deeper into the cortex and last longer.

Permanent colours
These colourants can be used to lighten or darken hair. People usually refer to them as bleaches (which I incidentally think is best used for toilets and not hair). Hair lightening is a better and a more precise way of explaining it. Lightening the hair a couple of shades involves a double-step process where you lighten the hair first to the level that you like to colour your hair to and then use the chosen hair colour on it.

Hair lightening products are also used to first decolour dark coloured hair, and then correct the hair colour. Permanent colours generally are a mix of two products (the colour + the developer). In this process, the cortex absorbs the colour in about 30 minutes, after which the oxygen in the developer swells the pigment in the colourant, and holds them in. The root may need retouching every six weeks. When retouching, make sure to colour only the new hair. If the new colour overlaps previously treated hair there will be a build-up of colour, which will make the hair more porous.

Vegetable colours
These colours are basically sourced from plant and vegetable sources. Amla, katha, henna, indigo, chamomile (yellow) and lemon are some of the sources for these colours. These natural colours work the same way as semi-permanent colourants. They stain the outside of the hair, however, results are variable. They also leave behind a residue that makes further colouring with permanent tints or bleaches inadvisable.

Hair tends to dry after you colour it, and needs special conditioning treatments at least once a month to help prolong the colour.

Colour also tends to fade on account of chlorinated water, weather and perspiration, you need to use special products that come with UV filters to counteract the fading and damage. Always rinse your hair thoroughly if you take a swim in chlorinated water. Use shampoos that have anti-oxidising properties, which prevent hair colour from fading. Conditioners with sealing properties also help retain the colour for a longer time. They tightly close the cuticles and restore the hair back to its normal ph (between 4.5 and 5.5) levels.