Calculations : Paint
Abbreviations
WFT = Wet Film Thickness
DFT = Dry Film Thickness
% VS = Percent Volume Solids
LF = Loss Factor
DV = Dead Volume
Formula for determining the DFT
Formula: DFT = WFT x % VS
100
Example:
WFT = 250 m
% VS = 50 %
250 x 50
DFT = = 125 m
100
3
Formula for determining the WFT
DFT x 100 %
Formula : WFT =
% VS
Example:
DFT = 100 m
% VS = 65 %
WFT = 100 x 100 % = 154 m
65 %
Formula for determining the
WFT after thinning (Method 1)
Formula: WFT = DFT x (100 % + % thinner)
% VS
Example:
DFT = 100 m
% VS = 65 %
Added thinner = 20 %
WFT = 100 x (100 % + 20 %) =185 m
65 %
Formula for determining the
WFT after thinning (Method 2).
DFT = 100 microns
% VS = 65 %
Added thinner = 20 %
Volume of paint = 1 litre New % VS:
65 = 54 %
Volume of thinner = 0,2 litre
1,2
New volume = 1,2 litre
WFT = 100 % x 100 microns = 185 m
54 %
Theoretical spreading rate
% VS x 10
Formula: = m2/litre
DFT
DFT = 100 microns
% VS = 65
10 = Factor
Spreading rate: 65 x 10
100
= 6,5m2/litre
Consumption of paint, no loss (1 of 2)
To be painted: Tank, area of 500 m2
Paint DFT % VS
Epoxy mastic 200 microns 85 %
Polyurethane topcoat 50 “ 50 %
Area (m2) x DFT
Consumption = = litre
10 x % VS
Consumption of paint, no loss (1 of 2)
To be painted: Tank, area of 500 m2
Formula: Area, m2 x DFT
10 x % VS
Epoxy mastic 500 x 200 = 117,7 litre
10 x 85
Polyurethane topcoat 500 x 50 = 50,0 litre
10 x 50
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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 Efficiency
Epoxy mastic 500 x 200 = 196 litre
10 x 85 x 0,6
Polyurethane topcoat 500 x 50 = 83 litre
10 x 50 x 0,6
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
Total Dead volume, litre = Area (m2) x DV x 100
% VS x Eff
Dead volume increases the
volume of paint required
Smooth (polished) steel surface
Even film thickness
Steel
Specified thickness
Uneven steel surface
Paint will fill the valleys Dead volume
Steel
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 (Efficiency) = 167 litre
Not 100 litre + 40 % extra = 140 litre
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
500 x 0,04 x 100
Litre dead volume = = 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 (PU)
10 x 50 x 0,6
Consumption of Paint with loss
To be painted: Tank, area of 1500 m2 , 30 % loss
Dicat dengan:
Jotamastic 87 Dft :200 Mic Volume solid 87%
Hardtop As Dft : 50 Mic Volume solid 50%
Consumption of Paint with loss
To be painted: Tank, area of 1500 m2 , 30 % loss
Cari quantity
Jotamastic 87 = litre
Hardtop AS = litre
Paint School
16
Consumption of Paint with loss
To be painted: Tank, area of 1500 m2 , 30 % loss
Formula: Area, m2 x DFT
10 x % VS x Efficiency
Jotamastic 87 1500 x 200 = 492.61 litre
10 x 87 x 0,7
Hardtop AS 1500 x 50 =214.29 litre
10 x 50 x 0,7
