Evaluation of Powders

EVALUATION OF POWDERS

Evaluation is carried out in order to know the quality of the finished product. General tests include determination of contents in the formulation along with the stability test. This is carried out to know whether the product remains stable for prolonged period of time (i.e.1 shelf life). Other tests are also carried out. They are:

1.           Shade Test

2.           Colour Dispersion Test

3.           Pay-off Test

4.      Pressure Test

5.           Breakage Test

6.           Flow Property Test

7.           Particle Size Determination

8.           Abrasive Character

9.           Moisture Content

1.          Shade Test:

In this test, the variations of colour shade is determined and controlled. It is carried out by spreading the powder sample on a white paper and appearance is observed which is compared with the standard one. Another method involves, applying powder sample and standard one with the help of puff on the skin and then comparing it. The puff used to perform this test is also used for the final product. Evaluation of colour is carried out by using artificial light.

2.          Colour Dispersion Test:

In this test, a sample of powder is spread on a white paper and with the help of magnifying glass., segregation or bleeding of the colour is observed. the colour should be properly distributed in the powder base of the formulation.

3.          Pay-off Test:

This test is carried out to check the adhesive property of powders with the puff. This test is mainly carried out on compact powders.

4.          Pressure Test:

For compaction purpose in compact powders, pressure required. Uniform pressure should be applied to avoid formation of air pockets, which will lead to either breaking or cracking of compact powders. This is because low pressure will make the compact powder soft, whereas high pressure will lead to formation of hard cake.

With the help of penetrometer, uniformity of hardness of the cake is checked. This is done by taking the reading at different points on compact powder and then comparing them.

5.          Breakage Test:

In this test, compact powders are allowed to fall on a wooden surface from a height of about 8-10 inches. This is carried out several times and then checking is done to see whether any breakage has occurred on compact powder. If the compact powder remains unbroken, then it shows the resistance to travel and normal handling by the users.

6.          Flow Property Test:

This test is carried out maim} on body powders to determine their flow property (from the container upon usage). This intern helps in easy application of powder to skin. In this method, angle of repose of powder is measured by allowing the powder product to fall on a plate through a funnel. Then the height and the radius of heap formed is measured, and even the time taken for the powder to fall is noted.

7.          Particle Size Determination:

With the help of microscope, sieve analysis or by utilizing other techniques and instrument, particle size of powder product is determined.

8.            Abrasive Character:

Abrasive character of powder can be determined by, rubbing, the powder on a smooth surface of the skin. Then with the help of a microscope, the effects of powder are studied.

9.           Moisture Content:

Moisture content present in the powder can be determined by using following formula.

Moisture Content % = Weight of water in sample × 5

                                                    Weight of dry sample

This is usually carried out by using various suitable analytical methods. These methods are also suitable for determining limits for colour.