Paint formulation guidelines

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 water-reducible 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 present-by 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 gram-mol 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:

Thickness of steel in mm 1 2 3 4 5 6 7 8 9 10 15 25 50
Surface in m / tonne steel 254 127 85 63 51 42 36 32 28 25 17 10,1 5,1

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 mixture-cross

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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6 Responses to Paint formulation guidelines

  1. Hildegard says:

    Excellent post. I was checking continuously this blog and I’m impressed! Very useful information specially the last part 🙂 I care for such info much. I was looking for this particular info for a long time. Thank you and good luck.

  2. Muralidhar K says:

    Very good info….

  3. Renu says:

    very good information. I would be helpful in project.

  4. Noble-guide Business Consult says:

    Great post, very helpful.

  5. MilanDas says:

    Require calculations of epoxy hardner vs epoxy resin and also calculation of PU hardner vs PU resin

  6. Elumalai says:

    superb!!!! post

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