#### Introduction

Most coatings consist of a binder matrix filled with solid particles, being pigments and/or fillers. The particles must be dispersed, stabilized and distributed in the paint. During film formation, when the wet paint transforms into a dry coating, the particles should stay uniformly distributed in the system.

#### Pigment Volume Concentration

The properties of a coating are governed by, amongst others, the **loading** of the system with solid particles. Some coatings contain a high amount of solid particles and other coatings, like clear coats, are free of particles. Particle loading is quantified by the Pigment Volume Concentration (**PVC**) of the system. The PVC of a system is defined as the volume percentage of solid particles in the system after film formation:

*Vp : total volume of all pigments in the system.*

*Vf : total volume of all*

**fillers**in the system.*Vb : volume of the non-volatile part of the*

**binders**in the system.#### Definition of Pigment Volume Concentration

The definition implies that the PVC of a system is calculated by leaving the volatile components, like water and solvents, out. The **volumes** of the non-volatile components should be used, implying that the weights of the solids must be transferred into volumes by using the density of each of the components.

A system of high PVC has a high loading and a system of low PVC contains a low amount of particles:

#### An example

Consider a white, gloss paint based on alkyd resin (EU) and titanium dioxide (EU) (TiO2):

For the ease of calculation we forget about the additives. The total volume of solid particles in 100 grams of this system can be calculated by dividing the weight of TiO2, 25.20 grams, by its density. This gives: **Vp = 6.00 cm3**. The paint does not contain filler: **Vf = 0**.

Now we have to calculate the non-volatile part of the binder. We know the following:

- The alkyd resin is dissolved in organic solvent, de-aromated white spirit D-40, having a density of 0.80 g/cm3.
- We must use the non-volatile part of the binder in the PVC calculation.
- The density of the alkyd solution is 1.00 g/cm3; this is not the density of the alkyd resin.

The 54.67 grams of alkyd solution contains 32.80 grams of alkyd resin and 21.87 grams of D-40. From the density of D-40, it follows that the alkyd solution contains 27.34 cm3 of solvent. The rest of the volume of the alkyd solution is the non-volatile alkyd resin: **Vb = 27.33 cm3**. From this analysis it follows that the density of the alkyd resin is 1.20 g/cm3.

By inserting the volume of the solid particles and the volume of the non-volatile part of the binder in the equation, it follows that the PVC of this system is **18.0%**.

#### Follow-up

To learn more about Pigment Volume Concentration, read “Effect of Pigment Volume Concentration on Coatings Properties – Part II” by expert Ron Lewarchik.

*The views, opinions and technical analyses presented here are those of the author, and are not necessarily those of UL, ULProspector.com or Knowledge.ULProspector.com. While the editors of this site make every effort to verify the accuracy of its content, we assume no responsibility for errors made by the author, editorial staff or any other contributor. All content is subject to copyright and may not be reproduced without prior authorization from Prospector.*

Dear Jochum,

thank you for this article. I think you have explained pvc very well and you took suitable examples of paint. When can I await the part II. This article is very suitable for the education of young people in the field of organic coatings.

Best regards

Ulrich christ

In principal, the aforementioned method to calculate the density of alkyd resin is not strictly correct. It implies an assumption that the volume of binder solution is the simple addition of solid binder volume and the solvent volume, which is most likely not true for a polymer solution. The best way to get the binder density is to directly measure it with a binder dry film.

Lanhui, you are correct in that it is best to use the measured density of the pure alkyd resin itself. However, most often this density is not known by the paint producer. For PVC calculations it is accurate enough to use the density of the resin solution and the density of the pure solvent and calculate the density of the pure resin from those two densities. This is only an approximation and it is best to indeed use the density of the pure resin, when available. For paint producers it is difficult to determine the density of a pure resin via a ‘binder dry film’.

Jochum

how can calculate the volume of non volatile for binder?

for example : i use 120 kg St/Ac in the formula density 1.02

applied the part of binder 60/1.02 or 60/1.02 -1

which one is correct?

In order to calculate the volume of the non-volatile part of a binder, a few things must be known:

1. Percentage of solid resin in the binder. Most often this is given in weight-%.

2. Density of the solid binder.

Often, ‘2’ is not known. In this case a fair approximation can be made. To show this, I use the example as given by Mohamed and I presume the following:

– It is a St/Ac dispersion based on water.

– The solid content is 60 weight-%.

The dispersion has a density of 1.02 g/ml and water has a density of 1.00 g/ml.

Let’s take 100 grams of the dispersion; this is 98.04 ml (using density of 1.02 g/ml).

40 weight-% is water; the volume of water is 40.00 ml (using density of 1.00 g/ml).

So, the remaining 60 grams of the dispersion is the non-volatile part of the binder and it occupies the remaining volume: 58.04 ml. This gives us the density of the non-volatile part of the binder = 1.03 g/ml.

Now, the purists know that the above is not true from physical point of view because we are allowed to add up weights but not volumes. However, in coating practice it turns out that this approximation does not lead to big errors.

Thank you sir

last several days I was trying to get the best way to understand the PVC of paint

Today I am extremely happy to learn about the pigment and binder relationship

thanks ones again

best regards

bl bhusal

Many thanks for your this article. I wish to digress a little from the subject. Perhaps you can help with my challenge. Here is my question, suppose I know the volume of resin solids, how do I calculate the quantity(volume) of resin (St/Ac)?

Dear Sir,

Could you please help me to calculate the % PVC paint formulation below:

Paint Recipe 100 gram density

PUD Binder 37.00 1.03

Acrylic Binder 20.00 1.1268

Biocide 0.15 1.04

Disperser Agent 0.10 1.1

Filler 28.18 2.7

Additive 0.13 1.069

Pigment White 12.00 1.80

co solvent 1.50 1.037

additive 0.30 1.04

defoamer 0.30 0.92

Additive 0.35 1.04

The thing that complicate, there are pigment white inside formulation which is has formulation as below:

Pigment White 100 gr density

solvent 15.35 0.99

water 27.51 1

co solvent 8.16 1.037

Titan dioxide 33.00 1.2

Filler 15.98 2.7

I get confused when try to calculate each pigment volume.

Based on that information could you help me to calculate the PVC of paint complete with calculation and please send your reply yo my email. Thank you so much for your kindly help

Dear Sir,

Could you please help me with a method to measure the ratio pigment/binder in the lab please,

It depends on the properties of the pigment and binders. For instance, if the pigment is quite thermal stable, such as TiO2, you can use TGA to get the ratio pigment/binder easily. Or, simply measure the weights before and after completely burning away the binders in a high temperature oven. Or, if the filler has some special characters, such as PTFE, you can use DSC to quantify the PTFE%.

Respected sir,

I have a question regarding true pigments and extenders.

Q-1) how we can differentiate true pigments and extenders visualy ?

for example tio2 and talc

Q-2) as qc chemist we are at customer end for the wrong supply of hardner i.e. for polyurathe coating. not sure either it is aliphatic or aromatic then how we can solve this problem at custmer end?