General notes on film thickness and spreading capacity

Volume solids

As the name implies the volume solids is the volume of the solid portion of the paint expressed as a % of the total volume of wet paint.

It can be determined practically (see BS3900 Part A10) or be calculated from the specific gravity of the individual components working from the % weight formula for the paint. The two methods may not give identical results.

The figures quoted in the Dulux Trade Product Information Sheets are calculated figures. Due to differences in specific gravities of pigments colours within a product line will vary. The specific colour to which the figure applies is quoted. Despite strict control on raw materials and paint manufacture a +2% tolerance around the quoted figure can be expected.

Theoretical spreading rate capacity

The theoretical spreading capacity (or coverage) in m²/ litre for any given film thickness can be worked out using the formula:

Volume Solids x 10

Dry film thickness in micro-metres