Site work instructions

Section 6 - Colour

SW 6.01 Good Working Practice When Using Colour

Before application, ensure that all materials are from the same batch. (See Clause SW 2.26). If mixed batch tins are purchased they should be 'boxed' to avoid potential colour variation. 'Boxing' requires the mixing together of the different batches in a larger container to ensure consistency of colour. Colour variation can occur when purchasing a colour for a project from a variety of sources rather than from one source and/or location. The risk of colour variation, can be reduced by taking the following action:

  • Avoid using a mixture of ready mixed colour and in store tinted colour.
  • Avoid using a variety of batch numbers whether ready mixed or in store tinted. For the purpose of in store tinted colour a batch is considered to be materials tinted on one machine at the same time.
  • Purchase sufficient material for the project at one time from the same source of supply tinted on the same tinting machine. Where this is not appropriate due to storage restrictions, the supplying merchant may be able to store sufficient quantities in store for call off when required.

It is good working practice to hold back sufficient original material to 'touch up' any areas of damage to the paint film prior to completion. With some paints and / or colours, especially products with mid or high sheen and / or deep colours, it may be necessary to recoat the whole area to avoid noticeable differences in film appearance for example under acute lighting conditions.

SW 6.02 Selection of Colours and Finishes/Trial Areas/Additional Coats

All colours and finishes to be selected and approved by the client or client's agent. Provision must be made for the execution of patterns or trial areas on site if required. In general, the quantity of finishing coats specified are based on ‘as existing' colours and finish types. Allowance must be made for any deviation from the standard specification. Additional coats may need to be applied should the client or client's agent select colours as described in Clause SW 6.04. ICI Paints will not accept responsibility for the cost of the application of additional coats when the originator of the documentation (for example an ICI Paints Representative) has not been informed of the colour schedule prior to origination of the project documentation.

SW 6.03 Specified - 'As Existing' Colour

Many specifications are written on the basis of the finish colour being 'As Existing'. Provision must be made by the successful Contactor, with the Client, to confirm and agree the 'actual' colours to be applied before application. Should a change of colour be instructed, then agreement must be reached by all parties as to the possible need for additional coats and the cost significance of such action. (See all other Clauses on Colour for further guidance.)

SW 6.04 Special Processes Colours

When any colour is to be used on rough surfaces, or where a marked change of colour is to be made, an amended process may be required and the finishing system for that surface amended to include the additional coats necessary. The finishing system for a surface that is to be significantly lighter than the previous colour (e.g. from Black to White) may also need to be amended to include the application of further coats of finish or the use of different colours or products as undercoats prior to finishing. Some strong colours, such as Poppy and Monarch in the revised BS4800 range, NCS colours with a colour intensity of 60 or more and also some Colour Palette colours as detailed below, cannot be made with the same hiding power as ordinary colours if they are to have satisfactory durability and purity of colour and therefore may require extra coats to be applied to achieve full opacity. These strong colours, known as 'Special Process Colours' are identified as such in colour cards from the supplying stockists or the Trade Technical Advice Centre (see below) with specific instruction on how many coats to apply to achieve full opacity. Some of this information will also be given on the can labels. This may involve the application of further coats of finish or the use of different colours or products as undercoats prior to finishing.
Refer to BS 6150: 2006 Code of Practice for Painting of Buildings Appendix B: Paint Colours (or as amended). See relevant colour card for further guidance.

Colour Guidance

  • NCS: All colours with a colour intensity of 60 or more. e.g. (1060-Y10R).
  • Colour Palette: BB, RB, BG colours with chroma value >350.
  • Colour Palette: YY, YR, GY colours with chroma value >450.
  • Colour Palette: RR, GG colours with chroma value >400.
    e.g. (45YY 71/664).

See also