OIL ABSORPTION

Test procedure for determination of oil absorption of pigments and extender.

DEFINATION :

The oil adsorbtion of a pigments is definrd as the number of grams of linseed oil absorbed by 100 gms of the pigment.

APPARATUS AND REAGENTS :

1. Glass weighing bottle 50 ml.
2. Glass tube.
3. Marble Slab or ground glass plate.
4. Sharp edged steel spatula..
5. Alalytical balance.
6. Clear raw linseed Oil.

PROCEDURE :

1. Weigh accurately about 10 to 15 gms of the test sample (for low oil absorption samples 20 to 25 gms could be used while for pigments such as carbon black 2 gms would be enough).

2. Fill the weighing bottle with raw linseed oil and insert the glass tube in it and weigh the bottle.

3. Place the weighed test sample on the glass plate or the marble slab.

4. Add the linseed oil from the bottle drop by drop and after each addition thoroughly mix the oil and the pigment by rubbing with the spatula.

5. Continue the addition of the oil till exactly enough oil has incropated in to the pigment to produce a very stiff paste which does not brak or separate. Spread the paste on the marble slab and with the satula gently roll the paste. It should roll without separation. This is the end point.

6. Reweigh the bottle with linseed oil and the glass tube.

7. It is improtant to do the testing duplicate or even thrice.

8. It is necessary to have few practical trials to attain proper skill.

CALCULATION :

A = Wt. or the test sample.
B = Initial wt. of the bottle with linseed oil.
C = Wt. of the bottle with linseed oil after the test.