LIPSTICK EVALUATION TESTS

VARIOUS EVALUATION TEST FOR LIPSTICK

Link for video demonstration of this topic 👇👇

https://youtu.be/59ywhxa9-HE

Various Evaluation methods are:

1. Melting point determination
2. Breaking load point test
3. Determination of thixotropic character
4. Microbiological tests
5. Test for rancidity
6. Test for the Application Force
7. Storage Stability
8. Stability to Oxidation
9. Determination of Surface Characteristic
10. Determination of Colour dispersion

1. Melting Point Determination Test: 

The determination of melting point is done in order to determine the storage characteristics of the product. The melting point of lipstick base should be between 60 to 65°C in order to avoid the sensation of friction or dryness during application. The method of determination is known as capillary tube method: 

(a) In this method, about 50 mg of lipstick is taken and is inserted into a glass capillary tube open at both ends. The capillary tube is ice cooled for about few hrs until it sets and then placed in a beaker containing hot water and a magnetic stirrer. The temperature at which material starts moving through the capillary is said to be the melting point temperature. 

(d) Another important parameter is the drop point which determines the temperature at which the product starts oozing out the oil and becomes flattened out. 

The melting point  determines the safe handling and storage of finished product. 

2. Breaking Load Point Test: 

This test is done in order to determine the strength and hardness of the lipstick. In this method, the lipstick is placed in horizontal position I inch from the base and weights with increasing loads are attached to it. the weight at which the lipstick starts breaking, known as the breaking load point. The test shall be carried out in specific condition and at about 25 ° C temperatures. 

3. Determination of thixotropic character: 

This is a test for determining the uniformity in viscosity of base. The instrument used for the determination of thixotropic character is known as the penetrometer. 

4. Microbiological tests: 

The test is carried out in order to determine the extent of contamination either from the raw materials or mould. The test involves the plating of known mass of sample on two different culture media for the growth of microorganism and incubating them for a specific period of time. The extent of contamination can be estimated by counting the number of colonies. 

5. Test for rancidity: 

The oxidation of oil such as castor oil and many other ingredients may result in bad odour and taste and also result in a sticky product. The test for rancidity can be done by using hydrogen peroxide and determining its peroxide number.

 6. Test for the Application Force: 

This is a test to determine the force to be applied during application. In this method, two lipsticks are cut to obtain flat surfaces which are placed one above other. A smooth paper is placed between them which is attached to a dynamometer to determine force required to pull the paper indicates the force application. 

7. Storage Stability: 

This test is done in order to determine the stability of product during storage. 

8. Stability to Oxidation:

The oxidation characteristics of the finished product are determined in order to check the stability of the product to oxidation. The extent of oxidation can be determined by peroxide number of product after exposure or substance to oxygen for a specific period of time. 

9. Determination of Surface Characteristics: 

The study of surface property of the product is carried out in order to check the formation crystal on the surface or the contamination by microorganism or formation of wrinkles and the exudation of liquid. 

10. Determination of Colour dispersion: 

The test is done in order to determine the uniform dispersion of color particle. The size of the particle is determined by the microscopic studies and it should not be more than 50µ.