Calculations
Paint School
JPS-E / Calculat / ‹#›
Calculations : Paint
Abbreviations
WFT = Wet Film Thickness
DFT = Dry Film Thickness
% VS = Percent Volume Solids
LF = Loss Factor
DV = Dead Volume
Paint School
JPS-E / Calculat / ‹#›
Formula for Determining the DFT
WFT = 250 microns
% VS = 50 %
DFT = WFT x % VS
100
DFT = 250 x 50 = 125 microns
100
Paint School
JPS-E / Calculat / ‹#›
Formula for Determining the WFT
DFT = 100 microns
% VS = 65 %
WFT = DFT x 100 %
% VS
WFT = 100 x 100 % = 154 microns
65 %
Paint School
JPS-E / Calculat / ‹#›
Formula for Determining the WFT
after thinning (Method 1)
DFT = 100 microns
% VS = 65 %
Added thinner = 20 %
WFT = DFT x (100 % + % thinner)
% VS
WFT = 100 x (100 % + 20 %) =185 microns
65 %
Paint School
JPS-E / Calculat / ‹#›
Formula for Determining the WFT
after thinning (Method 2).
DFT = 100 microns
% VS = 65 %
Added thinner = 20 %
65
Volume of paint = 1 litre New % VS: = 54 %
1,2
Volume of thinner = 0,2 litre
New volume = 1,2 litre
100 % x 100 microns
WFT = = 185 microns
54 %
Paint School
JPS-E / Calculat / ‹#›
Theoretical spreading rate
DFT = 100 microns
% VS = 65
10 = Factor
% VS x 10
DFT
= m2/litre
65 x 10
100 = 6,5m2/litre
Paint School
JPS-E / Calculat / ‹#›
Consumption of Paint
To be painted: Tank, area of 500 m2
Paint DFT % VS
Epoxy mastic 200 microns 85 %
Polyurethane topcoat 50 “ 50 %
Consumption = Area (m2) x DFT = litre
10 x % VS
Paint School
JPS-E / Calculat / ‹#›
Consumption of Paint with no loss
To be painted: Tank, area of 500 m2
Formula: Area, m2 x DFT
10 x % VS
500 x 200
Epoxy mastic 10 x 85
= 117,7 litre
Polyurethane topcoat 500 x 50 = 50,0 litre
10 x 50
Paint School
JPS-E / Calculat / ‹#›
Consumption of Paint with loss
To be painted: Tank, area of 500 m2 , 40 % loss
40 % loss implies that only 60 % will remain on the surface.
The correction factor, Loss factor, will be 0.6
Formula: Area, m2 x DFT
10 x % VS x loss factor
500 x 200
Epoxy mastic = 196 litre
10 x 85 x 0,6
Polyurethane topcoat 500 x 50 = 83 litre
10 x 50 x 0,6
Paint School
JPS-E / Calculat / ‹#›
Consumption of Paint with Loss
including Dead Volume (1 of 2)
A certain roughness will give a certain dead volume
Roughness, microns Dead volume, l/ m2
30 0.02
45 0.03
60 0.04
75 0.05
90 0.06
105 0.07
Area (m2) x DV x 100
Total Dead volume, litre = % VS x LF
Paint School
JPS-E / Calculat / ‹#›
Consumption of Paint with Loss
including Dead Volume (2 of 2)
Tank area 500 m2, 40 % loss, surface roughness 60 microns
DFT % VS
Epoxy mastic 200 85
Polyurethane topcoat 50 50
Litre dead volume = 500 x 0,04 x 100 = 39 litre (EM)
85 x 0,6
Epoxy mastic (EM) 500 x 200 = 196 litre (EM
10 x 85 x 0,6
Polyurethane topcoat 500 x 50 = 83 litre (EM)
10 x 50 x 0,6
Paint School
JPS-E / Calculat / ‹#›
How Much Paint Should We Order ?
Calculation of Paint Consumption With Loss
A loss of 40 % means that only 60 %
will be applied on the surface
Example: 100 litre is needed, loss is 40 %
We have to order
100 x 100 100
60 = 0,6 (loss factor) = 167 litre
Not 100 litre + 40 % extra = 140 litre
Paint School
JPS-E / Calculat / ‹#›
