hempel a/s - Marsadom

CORPORATEHEMPEL PAINT SYSTEMS5 USEFUL DEFINITIONS6 HEMPEL PAINT SYSTEMSThere are several useful definitions and termsused in coating protection technology. Weprovide you here with few necessary termsthat you should be acquainted with whendealing with paints:Volume solidsThe volume solids (VS) figure expresses asa percentage the ratio of:Dry film thicknessWet film thicknessThe stated figure has been determined asthe ratio between dry and wet film thicknessof the coating applied in the indicated thicknessunder laboratory conditions, where no paintloss has been encountered.Theoretical Spreading RateThe theoretical spreading rate of the paintin a given dry film thickness on a completelysmooth surface is calculated as follows:Volume solids % x 10 = m 2 /litreDry film thickness (micron)Practical ConsumptionThe practical consumption is estimated bymultiplying the theoretical consumption witha relevant Consumption Factor (CF).The consumption factor or the practicalconsumption cannot be stated in theproduct Data Sheet because it dependson a number of external conditions suchas:a. Waviness of paint film:When paint is manually applied the film willshow some waviness on the surface. It willalso have an average thickness higher thanthe specified dry film thickness in order tofulfil the 80:20 rule for example. This meansthe paint consumption will be higher thanthe theoretically calculated amount if youwant to reach the minimum specified filmthickness.b. Size and shape of the surface:Complex and small-sized surfaces will leadto higher consumption through overspray,than the square, flat area which was usedto work out the theoretical calculation.c. Surface roughness of the substrate:When a substrate has a particularly roughsurface this creates a “dead volume” whichuses more paint than if the surface wassmooth and this will affect any theoreticalcalculations. In the case of shopprimers witha thin film, this has the effect of seeminglylarger surface causing higher consumptionas the paint film covers irregular surfacehollows.d. Physical losses:Factors such as residues in cans, pumps andhoses, discarded paint due to exceeded potlife, losses due to atmospheric conditions,insufficient skills of a painter etc. will allcontribute to a higher consumption.RECOMMENDED PAINT SYSTEMSFOR VARIOUS ATMOSPHERIC CORROSIVITY CATEGORIES& OTHER TYPES OF ENVIRONMENTS(in accordance with ISO 12944-5:2007)C1/C2 CORROSIVITY CATEGORYC3 CORROSIVITY CATEGORYC4 CORROSIVITY CATEGORYC5-I CORROSIVITY CATEGORYC5-M CORROSIVITY CATEGORYIMMERSED STRUCTURESHEAT RESISTANT STRUCTURES22For further definitions or explanations, please contact your localHempel representative.