Reducing colour variation

ICI Paints produces the highest quality paints for professionals backed up by the highest quality support. As part of this service, they offer invaluable advice to contractors about colour to help them achieve a perfect job, from tender to completion, each and every time.

Our eyes and colour variation

The human eye can differentiate between 10 million colours, and the way buildings are lit can alter that perceived colour. However, although humans have been making and using colours for thousands of years, fundamental issues still arise.

Current paint technology still means we live in a world of variables and while they may be very small, they can still be significant. For example, manufactured pigments differ from batch to batch; tinting machines produce slightly different strength colours each time and other raw materials will vary every time a paint is made. This is why, historically, the paint industry has always experienced batch-to-batch variation on ready mixed paints.

Over the last 20 years, the UK trade market has moved away from ready-mixed to predominately tinted paint. Whilst this gives merchants and end users greater advantages, it also introduces more colour variation.

That said, there are 5 simple rules that can minimise the impact of the colour variation:

1. Use a single batch for a job or a discrete area, i.e. a paint that is tinted from the same tinting machine at the same time. Do not use paint from different batches on the same surface or surfaces close together. If possible, purchase paint for the whole job at one time. If storage is limited, your merchant may be able to help.
2. If you have mixed batches of coloured paint then they should be ‘boxed’: mixing all the paints in a large container ensures colour consistency. If this is impossible, use the different batches in areas where the colour cannot be directly compared.
3. Use either ready-mixed or tinted paint; do not use both on the same job.
4. Check the colour of each batch before you use it. ICI Paints' colours are available in the fanbooks and colour cards or you can request an A8 Colour Palette sample. The project specifier should also supply a sample for you to check against. Another option is to ask your client to agree that the colour (and quality of the paintwork) is in line with the specification by signing-off a small test area at the beginning of the contract. Please bear in mind that the appearance of a colour can depend on the type of lighting. Therefore check the colour in the actual lighting conditions that will be used. The client may not ask for this so painting contractors need to be proactive in requesting this check. If you come across a problem, contact ICI Paints before you use the paint. Or, if you are already using the product, no more should be applied*.
5. 'Touching up' should only be attempted using paint from the original job using the same application methods. Therefore, paint should be reserved specially for this purpose. It is recommended that touching up is carried out up to a break in the wall or surface. With particular colours, usually deeper shades, and higher sheen finishes it may be necessary to recoat the whole area to avoid noticeable differences in appearance.

To help your staff, a summary of this advice can be found on the lids of all tinted paint cans.

* from BS 6150 : 2006 - Code of practice for painting of buildings.