Evaluation of Nail Lacquers

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Chapter: Textbook of Cosmetic Formulation : Nail Lacquers

The various methods required for the evaluation of nail polishes are as follows.


EVALUATION OF NAIL LACQUERS

 

The various methods required for the evaluation of nail polishes are as follows.

 

1.             Test For Non-Volatile Content:

 

The test is done in order to check the quantity of the non-volatile content in the preparation. The method is known as dish method and involves a simple process described below:

 

The sample is spread on a flat plate as a circle 8 cms in diameter.

 

 

The quantity is weighed and kept in an oven at a temperature o 105 for l hr.

 

 

The quantity of substance remaining on the plate is weighed arid this constitutes the non-volatile content.

 

2.    Rate Of Drying:

 

The test is done in order to check the rate of evaporation of the preparation. It involves a simple process in which the film is applied with an applicator on to a completely non-porous surface. It is kept at 25°C and 50% RH and the time required to dry is noted by touching it with finger. When no matter is adhered to the finger tip, then the product is said to be completely dried.

 

3.             Colour Of The Product:

 

The colour of the product is tested by comparing it with, a standard colour. This can be done by applying the standard colour on one nail and the prepared product on the adjacent nail. From this comparison, the contrast in the colours can then be easily noted.

 

4.            Test For Smoothness Of The Film:

 

The smoothness is the most important characteristic of the film. The surface property can be studied by the microscopic analysis. The film should not contain any foreign matter or particles of the coating material. It should also be free from the orange peel effect when seen under microscope.

 

5.              Estimation Of Gloss:

 

The gloss of the product can be determined by the use of an instrument that works on the principle of reflection of light.

 

6.          Test For Hardness Of The Film:

 

The test is done in order to measure the extent of hardness of the substance.

It is done by spreading the film on a glass plate and then drying it for 48 hrs at 25°C.

It is then further dried at 70°C for 2hrs.

It is then cooled at 25°C for 48 hrs.

The hardness is then checked by applying mechanical force externally.

 

7.          Test For Adhesive Property:

 

This is done in order to measure the extent of adhesion of the film with adhering material. This is done by the following method.

 

The film is spread on metal surface and allowed to settle for some time.

 

The adhesion character is then determined by measuring the mechanical force applied externally to remove the film.

 

8.           Test For Resistance To Abrasion:

 

This is done by applying mechanical abrasive forces externally on the film surface. The surface characteristic of the film before and after the application of abrasive force are then studied.

 

9.           Test For Resistance To Water Permeability:

 

This is a measure of resistance of the film towards absorption of water. This is done as follows.

A continuous film is spread on the surface of a metal plate.

The plate is then immersed in water.

The weight of the film before and after the immersio n into water is noted.

An increase in the weight is calculated. The lesser the increase in weight, the greater is the water resistance.

 

10.         Test Application Property:

 

It is a measure of ease of application of the product. It is carried out more reliably by applying on nails. The degree of evenness and smoothness of brushing and the presence of any air bubbles are checked out.

 

11.         Test for Viscosity:

 

It is the most important parameter that determines the evenness of application.

The viscosity can be measured by using Brookfield‘s viscometer.

It can be easily carried out by checking the flow of product from the applicator and comparing it with standard product.

 

12.                      Test For Stability:

 

It is it measure of long lasting ability of the product. It can be done by using the acceleration stability test.

 

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