CALCULATIONS ON PAINT FORMULAS
1. Density
Density of paint is:
Total sum by weight of each ingredient in paint
Total sum by volume of each ingredient in paint
2. Solid content
Solid content by weight of paint is:
Total sum by weight of each solid ingredient in paint x 100%
Total sum by weight of each ingredient in paint
Solid content by volume of paint is:
Total sum by volume of each solid ingredient in paint x 100%
Total sum by volume of each ingredient in paint
3. Pigment Volume Concentration
PVC paint is:
Total sum by volume of all pigments + extenders in paint x 100%
Total sum by volume of each solid ingredient in paint
4. Critical Pigment Volume Concentration
The best way to determine the critical PVC of a paint is to measure the volume of the dry pigment/extender mix of a paint in a centrifuge and to calculate the CPVC as follows:
CPVC = (calculated volume pigment/extender mix / volume after centrifuge) x 100
or
CPVC = ( f x G x 100) / (dPi x Va)
f = ratio weight pigments and total weight solid content paint
G = weight of dry film
dPi = density of pigment/extender mix
Va = geometric volume of paintfilm (e.g. 250 micron wet filmthicknes x length x width)
A theoretical calculation which estimates the approximate CPVC is:
CPVC = (volume pigment+extender x 100) / (volume pigment+extender) + ((average o.a. pigment+extender) / 0,93)
5. Extender replacement
To calculate an extender replacement by weight by another extender and maintaining PVC:
E = A1 x D2
A2 x D1
E = factor to multiply with original extender weight to calculate weight substituting extender
A1 = OA of original extender
A2 = OA of substituting extender
D1 = density of original extender
D2 = density of substituting extender
6. Crosslinking percentage of two component products
· Epoxies
Equivalent weight epoxy component base paint is:
Weight base paint
Weight epoxy resin (1) + Weight epoxy resin (2) +
Eq.w.epoxy resin (1) Eq.w. epoxy resin(2)
Equivalent weight amine component harder is:
Weight harder
Weight amine (1) + Weight amine (2) +
Eq.w. amine (1) Eq.w.amine (2)
Crosslinking percentage = Weight harder x Eq.w. base component x 100%
Weight base x Eq.w. harder component
Polyurethanes
Equivalent weight polyol component base paint is:
Weight base paint
Weight polyol resin (1) + Weight polyol resin (2) +
Eq.w.polyol resin (1) Eq.w. polyol resin(2)
Equivalent weight isocyanate component harder is:
Weight harder
Weight isocyanate (1) + Weight isocyanate (2) +
Eq.w. isocyanate (1) Eq.w.isocyanate (2)
Crosslinking percentage =
Weight harder x Eq.w. base component x 100%
Weight base x Eq.w. harder component
7. Calculation the amount of amine to neutralize waterreducible resins
Equation: A = R (AN) E
56.100
Where:
A = weight of amine
R = weight of resin, non volatile
AN = acid number resin, non volatile
E = equivalent weight of amine
8. Starting point amounts of hydroxy / carboxy / amide containing resins in melamine / urea resins combinations in oven cured systems
Let:
x = hydroxyl number (mg of KOH to neutralize the organic acid required to esterify the hydroxyl groups present)
y = acid number (mg of KOH required to neutralize one gram of resin)
z = amide number (mg of KOH equivalent to reactivity of the amide groups presentby calculation)
Then: 56 grams (mol.wt. KOH) = gram mol. of resin to be crosslinked
x + y + z (mg)
Example: the equivalent weight of a melamine resin is 130
If a polyester resin has a hydroxy number of 60, an acid number of 5 and an amide number of 0, the grammol weight of the polyester is:
56 grams = 861,5 grams
60+5+0 mg
Or the starting levels for the binder may be polyester / melamine resin = 861,5 / 130
Or polyester / amino = 87 /13 by weight on solids
9.Volatile Organic Compounds (VOC’s with vapour pressure > 0,01 kPa at 20 C)
VOC = weight volatile organic material (g/l)
Volume paint (without water
VOC = 100 – NV% – water% x 1000 (g/l)
(100/density) – water%
For solvent based coatings the formula simplifies to:
VOC = (100 – NV%) x 10 x density (g/l)
10.Theoretical spreading rate paint at given filmthickness:
Volume solids = liters/m2
Film thickness in microns : 10
Volume solids = kg/m2
(Film thickness : 10) x density solids paint
Price per m2 at given film thickness:
Price per liter
Theoretical spreading rate in liters
Relation thickness steel construction and surface:

11. Required air quantities to stay below MAC levels:
∑ ( TLV per ingredient x weight %)
12.Required air quantities to stay below lowest explosion limits:
∑ ( LEL per ingredient x weight %)
13.General formulae for mixing liquids
A = C – B
B = C (a – c)
a – b
C = B (a – b)
a – c
Where:
A = weight of original liquid a = its content in % by weight
B – weight of diluent b = its content in % by weight
C = weight of prepared mixture c = its content in % by weight
For water as diluent, b = 0
14. HLB (hydrophylic – lipophylic – balance) of surfactants and their activity features
0 – 4 = defoaming
3 – 7 = emulsifying
7 – 15 = penetrating
7 – 20 = emulsifying
12 – 20 = detergency
15 – 20 = solubilising
15.Mixing rules by using mixturecross
How much of each solution has to be mixed to get a 62% solid solution of a 54% solids solution with a 92% solids solution?
30 parts by weight of 54% solid solution must be mixed with 8 parts by weight of 92% solid solution to yield a 62% solid solution.
92 – 62 = 30 pbw 54% solution
62 – 54 = 8 pbw 92% solution
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very good information. I would be helpful in project.
Great post, very helpful.
Require calculations of epoxy hardner vs epoxy resin and also calculation of PU hardner vs PU resin
superb!!!! post
What does o.a. mean?
O.A. = oil absorption of a pigment