SMOOTHNESS OF EXTENDER

This test is simple to perform. SMOOTHNESS is mainly compared to understand contamination, impurities and coares particles. It is just a qualitative method to detect impurities and variation.

PROCEDURE :

Take a pinch of extender sample between the fingers and rub the fingers. Judge the smoothness. Similarily do for the master sample. Judge the difference.

NOTE :
For more accurate method do the same operation with one fingure on a glass plate or tile.

BULKY DENSITY APPARATUS REQUIRED : 1. Glass cylinder graduated 50 ml. 2. Thin piece of rubber sheet. PROCEDURE : Place rubber sheet on working table. Weigh exactly the clean dry glass cylinder. Add into the cylinder the sample powder in small lots and after adding tap the bottom of cylinder on rubber sheet and futher powder. This way keep adding powder and tapping the cylinder till the powder level comes to 50 ml. marking. This way we get a stiff well knit packing of powder inside the cylinder. Now weigh the cylinder again and note. CALCULATION : B = WT. OF CYLINDER AND SAMPLE. A = WT. OF EMPTY CYLINDER. BULK DENSITY (KGS/LTR) = (B-C) 50

WHITENESS OF EXTENDER

This a test covers the methods to compare the whitness of an extender against approved and previously stored master sample. This is a quick and easy method to approve or reject the supplies based on its colour immediately on receipt.

APPARATUS AND REAGENTS :

1. 4" x 4" clean glass plate.

2. Spatula.

3. Mineral turpentine

4. Previously approved master sample.

PROCEDURE :

Place asmall amount of the extender sample on the glass plate. Carfully flatten the sample using a spatula. Now keep the master sample near the test sample. Flatten the master sample. Do it carfully so that the samples inspite of being close do not mix up or touch each other. Carefully wet both samples adding mineral turpentine drop by drop and observe the colour of sample from the back of plate mineral turpentine helps to hold the powder on the glass plate. Observe the colour of both samples and report.

note to report the difference in tone between sample and master as comparable, cleaner, yelloer, reddish etc.

PH VALUE

Test Methods for determining the PH Value of 5% slurry of pigments and extenders.

APPARATUS REQUIRED :

1. Erlenmeyer flask. (Glass Stoppered) 125 ml.

2. Glass beaker 100 ml.

3. PH meter.

4. Distilled Water.

PROCEDURE :

Weight accurately 5 gms of the test sample and transfer in the erlenmeyer flask. Add a 100 ml. of the distilled water into the flask, stopper the flask and mix its contents thoroughly by shaking for about a minute. Keep the flask aside for one hour caliberate the PH meter in accordance with the manufacturers instructions. Transfer an appropriate amount of the clear aqueous solution from the flask into the beaker. Keep beneath the cell of the PH meter and note the PH value and report.

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.

SIEVE RESIDUE

This method covers the best procedure for the determination of fesidue on sieve for water insoluble pigments and extenders.

APPARATUS AND REAGENTS :

1. Sieve of the reqired specification.
2. Soft camel hair brush.
3. Evaporating dish 250 ml.
4. Beaker 250 ml.
5. Glass rod.
6. Oven.
7. Ethanol.

PROCEDURE :

1. Weigh accurately to the nearest mgs about 15 to 20 gms of the test sample. 25 gms should used for heavier pigments/extenders.

2. Transfer the sample into a 250 ml beaker. (Add few drops of ethanol or any suitable wetting agent for organic pigments)

3. Add 100 to 150 ml of water into the beaker and slowly stir with the help of a glass rod, till the sample in thoroughly wetted.

4. Transfer the contents of the beaker into the specified sieve and hold the sieve under tap water. Such that the tap water flows at a low pressure.

5. Gently brush the contents with brush till washings flowing out the sieve and hold the sieve done not contain any sample particles. Generally it takes about 5 to 10 mns for the completion of the above procedure.

6. Collect the residue life in the sieve carfully into a previously weighed clean evaporating dish. Take care to transfer the particles adhering to the brush.

7. Dry the dish along with the residue in an oven at 120^o C.

8. Test to be done in duplicate.

CALCULATION :

A = Wt. of the test sample.
B = Wt. of empty evaporating dish.
C = Wt. of evaporating dish and the residue.
C-B = Wt. of the residue.

WATER SOLUBLE MATTER

This method covers the determination of water soluble matter in pigments and extenders.

APPARATUS AND REAGENTS :

1. Beaker 250 ml.
2. Gas burner.
3. Glass rod.
4. Whatman filter paper No.5.
5. Evaporating dish 250 ml.
6. Desiccator.
7. Distilled water.

PROCEDURE :

1. Weigh accurately to the nearest mgs. 15 to 20 gms of the test sample.

2. Transfer the weighed sample into a clean 250 ml beaker.

3. Add 100 ml of distilled water.

4. Mix the contents thoroughly with the help of a glass rod. (Practicularly for organic pigments before adding water it is better to wet the pigment with few drops of alcohol or any suitable wetting agent).

5. Gently boil the beaker and its contents and filter using whatman filter paper No.5.

6. Collect the filterate in a clean dry previously weighed evaporating dish.

7. Evaporate the water carefully and when dry cool in desiccator and reweigh the evaporating dish.

8. Test to be done in duplicate.

CALCULATION :

A = Wt. of empty evaporating dish.
B = Wt. or the test sample.
C = Wt. of evaporating dish with the water solubles.
C-A = Wt. of the water soluble matter.

MOISTURE CONTENT

This method covers the procedure for the determination of moisture content in pigments and extenders and is applicable for samples which do not decompose below 110deg.C..

APPARATUS AND REAGENTS :

1. Glass petri-dish : Approx. dia 70-80 mm ht. 20-30
2. Oven.
3. Analytical balance.
4. Desiccator.

PROCEDURE :

1. Weigh the clean and dry glass petri dish.

2. Add about 5gms of the test sample accurately weighed to the nearest mgs in the dish. The should be spread uniformly in the dish.

3. Keep the dish in the oven maintained at 105 deg.C. to 110 deg.C. for 1 hour.

4. Remove the dish from the oven and cool it in a desiccator.

5. Reweigh the dish with the sample.

6. Test to be done in duplicate.

CALCULATION :

A = Wt. of the petri-dish.
B = Wt. of petri-dish and sample before drying.
C = Wt. of petri-dish and sample after drying.
B-A = Wt. of sample before drying.
C-A = Wt. of sample after drying.