S.I. No. 159/1949:

STANDARD SPECIFICATION (LINSEED OIL FOR PAINTS) ORDER, 1949.

STANDARD SPECIFICATION (LINSEED OIL FOR PAINTS) ORDER, 1949.

I, DANIEL MORRISSEY, Minister for Industry and Commerce, in exercise of the power conferred on me by subsection (3) of section 20 of the Industrial Research and Standards Act, 1946 (No. 25 of 1946), hereby order as follows :

1. This Order may be cited as the Standard Specification (Linseed Oil for Paints) Order, 1949.

2.--(1) The specification set forth in Part II of the Schedule to this Order is hereby declared to be the standard specification for the commodity described in Part I of the said Schedule.

(2) The said standard specification may be cited as Irish Standard 14 : 1949.

SCHEDULE.

PART I.

LINSEED OIL FOR PAINTS.

PART II.

SPECIFICATION.

In this specification, the letters B.S., when followed by two sets of numbers, refer to the British Standard of which the first is the serial number and the second is the year of its publication by the British Standards Institution.

SCOPE.

1. This specification applies to linseed oil of the following types :

(a) raw linseed oil obtained from linseed by expression or solvent extraction,

(b) refined linseed oil consisting of non-acid refined linseed oil or acid refined linseed oil, and

(c) boiled linseed oil consisting of linseed oil which has been boiled.

DESCRIPTION.

2. Linseed oil shall be free from admixture with other oils or fats.

Linseed oil when kept at a temperature of 15° C./20° C. for 24 hours shall be free from insoluble matter.

COLOUR.

3.--(a) Raw linseed oil when filtered shall be not darker than the agreed sample.

In the absence of an agreed sample raw linseed oil shall be not darker than a freshly made solution of 0·08 grams of iodine and 0·8 grams of pure potassium iodide, free from iodate, in 100 millilitres of water.

(b) Refined linseed oil shall be not darker than a freshly made solution of 0·02 grams of iodine and 0·2 grams of pure potassium iodide, free from iodate, in 100 millilitres of water.

(c) Boiled linseed oil when filtered shall be not darker than the agreed sample.

For the purpose of comparison of colour the linseed oil and the iodine solution, or agreed sample, shall be placed in similar glass tubes 1 centimetre in diameter and 10 centimetres long, and viewed transversely by transmitted light.

SPECIFIC GRAVITY.

4.--(a) Raw linseed oil. The specific gravity of raw linseed oil at 15·5° C./15·5° C. shall be not lower than 0·930 and not higher than 0·938.

(b) Refined linseed oil. The specific gravity of refined linseed oil at 15·5° C./15·5° C. shall be not lower than 0·930 and not higher than 0·935.

(c) Boiled linseed oil. The specific gravity of boiled linseed oil at 15·5° C./15·5° C. shall be not lower than 0·935 and not higher than 0·945, and shall be within plus or minus 0·002 of the specific gravity of the agreed sample.

REFRACTIVE INDEX OF RAW LINSEED OIL AND OF REFINED LINSEED OIL.

5.--(a) Raw linseed oil. The refractive index of raw linseed oil for the D line at 20° C. shall be not lower than 1·4800 and not higher than 1·4835.

(b) Refined linseed oil. The refractive index of refined linseed oil for the D line at 20° C. shall be not lower than 1·4808 and not higher than 1·4824.

For the purpose of this clause the refractive index may be determined at any temperature from 15° C. to 25° C. and the refractive index at 20° C. calculated from the result so obtained by subtracting 0·00037 therefrom for each degree centigrade by which the temperature is lower than 20° C., or by adding 0·00037 for each degree centigrade by which the temperature is higher than 20° C.

IODINE VALUE OF RAW LINSEED OIL AND OF REFINED LINSEED OIL.

6. The iodine value of raw linseed oil and refined linseed oil when determined by the method described in Appendix A shall be not lower than 170.

SAPONIFICATION VALUE OF RAW LINSEED OIL AND OF REFINED LINSEED OIL.

7. The saponification value of linseed oil when determined by the method described in Appendix B shall be not lower than :

188 for raw linseed oil and

189 for refined linseed oil.

ACIDITY.

8. The linseed oil shall be free from mineral acids and added organic acids. The acidity of each type of linseed oil when determined by the method described in Appendix C shall not exceed the amount set out below :

(a) Raw linseed oil :

the equivalent of 6 milligrams of potassium hydroxide per gram of linseed oil or 3·0 per cent. of free fatty acids calculated as oleic acid.

(b) Refined linseed oil :

(i) Non-acid refined linseed oil: the equivalent of 4 milligrams of potassium hydroxide per gram of linseed oil or 2·0 per cent. of free fatty acids calculated as oleic acid.

(ii) Acid refined linseed oil: the equivalent of 9 milligrams of potassium hydroxide per gram of linseed oil or 4·5 per cent. of free fatty acids calculated as oleic acid.

(c) Boiled linseed oil :

the equivalent of 8 milligrams of potassium hydroxide per gram of linseed oil or 4·0 per cent. of free fatty acids calculated as oleic acid.

DRYING TIME.

9. A film of linseed oil prepared by the method described in Appendix D shall become surface dry at a temperature and humidity agreed to between the purchaser and vendor, in not more than four days for raw linseed oil and refined linseed oil, and twenty-four hours for boiled linseed oil.

For the purposes of this clause the term " surface dry " shall mean a condition such that clean dry silver sand sprinkled on to the surface of the linseed oil film and kept there for one minute, can be removed by means of a camel hair brush without injury to the linseed oil film. The sand used shall be graded so as to pass a No. 52 British Standard Test Sieve conforming to B.S. 410 : 1943, and to be retained on a No. 100 British Standard Test Sieve conforming to B.S. 410 : 1943.

UNSAPONIFIABLE MATTER.

10. Raw linseed oil and refined linseed oil when tested by the method described in Appendix E shall not contain more than 2 per cent. of unsaponifiable matter.

Boiled linseed oil when tested by the method described in Appendix E shall not contain more than 2·5 per cent. of unsaponifiable matter.

ROSIN IN BOILED LINSEED OIL.

11. Boiled linseed oil shall contain not more than one per cent. of rosin.

SAMPLING AND SIZE OF SAMPLE.

12. Representative samples, each measuring not less than one imperial pint, shall be taken in triplicate from one or more original and previously unopened containers, or from the bulk during filling. They shall be packed in clean, dry air-tight non-absorbent containers made of material on which the sample has no action. The containers shall be of a size such that they are nearly filled by the sample. Each container so filled shall be sealed and shall be marked with the date of sampling, and with sufficient information to identify the sample.

AGREED SAMPLE.

13. Except where otherwise agreed between purchaser and vendor the agreed sample referred to in this specification shall comply in all respects with the requirements of this specification. It shall measure not less than one imperial pint and shall be packed in the manner described in Clause 12.

APPENDIX A.

Method for the determination of Iodine value.

Weigh accurately 0·20 g. to 0·25 g. of the linseed oil and dissolve in 10 ml. of carbon tetrachloride which shall be inert to Wijs solution in a clean, dry, narrow-mouthed bottle such as an iodine flask of about 500 ml. capacity, provided with a glass stopper. Add 50 ml. of Wijs solution prepared by one of the methods described below and seal the bottle with the stopper moistened with the minimum quantity of a 10 per cent. solution of pure potassium iodide free from iodate.

Keep the bottle in a dark place for one hour at a temperature of 15° C. to 20° C. Add 20 ml. of a 10 per cent. solution of pure potassium iodide free from iodate and then add 150 to 200 ml. of distilled water. Titrate, with starch as indicator, the free iodine in the solution with standardised sodium thiosulphate solution of approximately N/10 strength. Make a blank determination upon the same quantities of reagents, at the same time and under the same conditions

The iodine value is

x is the volume in ml. of N/10 thiosulphate solution required for the blank, and

y is the volume in ml. of N/10 thiosulphate solution required when the linseed oil is used, and

W is the weight in grams of linseed oil taken.

PREPARATION OF WIJS SOLUTION.

The glacial acetic acid used in the preparation of the solution shall comply with B.S. 576 : 1934 and further, when 10 ml. of concentrated sulphuric acid (sp. gr. 1·84) containing 0·05 ml. of saturated potassium dichromate solution are added to 10 ml. of the acetic acid, the mixture shall show no immediate formation of green colour.

Method 1.--Dissolve 8 g. of iodine trichloride in approximately 450 ml. of glacial acetic acid. Dissolve 9 g. of iodine in a further 450 ml. of glacial acetic acid, and, if necessary, heat gently to effect solution. Add gradually the solution of iodine in glacial acetic acid to the solution of iodine trichloride until the colour has changed to a reddish brown ; then add a further 50 ml. of the iodine solution and dilute the mixture with glacial acetic acid until 10 ml. of the mixture is approximately equivalent to 20 ml. of N/10 sodium thiosulphate solution when the halogen content is determined by titration in the presence of an excess of potassium iodide and water. Heat the Wijs solution thus prepared to 100° C. for 20 minutes and allow to cool. During the preparation of the solution access of water vapour shall be prevented.

Method 2.--Dissolve 12·7 g. of iodine free from iodate in 1 litre of glacial acetic acid heating gently to effect solution. Cool the solution so obtained and determine the halogen content by titrating 10 ml. with standardised sodium thiosulphate solution of approximately N/10 strength in the presence of an excess of potassium iodide and water. Pass a stream of dry chlorine into the iodine solution until the halogen content as determined by further titration in the presence of an excess of potassium iodide and water, has been approximately, but not more than, doubled.

Heat the Wijs solution thus prepared to 100° C. for 20 minutes and allow to cool. During the preparation of the solution access of water vapour shall be prevented.

APPENDIX B.

Method for the determination of Saponification value.

Weigh accurately about 2 g. of the linseed oil into a flask and boil for half-an-hour under a reflux condenser with 25 ml. of alcoholic potassium hydroxide of approximately N/2 strength. While the solution is still hot determine the excess of alkali by titration with hydrochloric acid of N/2 strength, using 0·5 ml. of a 1·0 per cent. alcoholic solution of pure phenolphthalein as indicator.

Make a blank determination of the same quantity of potassium hydroxide solution at the same time under the same conditions.

The saponification value is

x is the volume in ml. of N/2 acid required for the blank, and

y is the volume in ml. of N/2 required when the linseed oil is used, and

W is the weight in grams of linseed oil taken.

APPENDIX C.

Method for the determination of Acidity.

Dissolve 10 g. of the linseed oil in 25 ml. of neutral benzene and slowly add to the solution, with constant shaking, 50 ml. of neutralised alcohol. Titrate the mixture so obtained with N/10 sodium or potassium hydroxide using, as indicator, 0·5 ml. of a 1·0 per cent. alcoholic solution of phenolphthalein.

The acidity expressed as the equivalent of milligrams of potassium hydroxide per gram of linseed oil is x x 0·561, and the acidity expressed as the percentage of free fatty acids calculated as oleic acid is x x 0·282, where x is the volume in ml. of N/10 alkali required for the test.

APPENDIX D.

Method for the determination of Drying Time.

Brush the oil on to the ground surface of a ground-glass panel about 10 cm. square. Place the panel in a vertical position in a well ventilated room so that the surface of the panel is illuminated by diffused daylight for at least six hours of each day of the drying period. During the drying period the temperature of the room shall be between 15° C. and 20° C. and shall be above the dew point.

APPENDIX E.

Method for the determination of Unsaponifiable matter.

Weigh accurately 2·0 g. to 2·5 g. of linseed oil into a 250 ml. flask and add 25 ml. of alcoholic potassium hydroxide of strength approximately, but not weaker than, N/2. The alkali solution shall not be darker than a straw colour. Attach the flask and contents to a reflux condenser and heat on a steam bath for one hour, with occasional swirling to ensure complete saponification.

Remove the flask from the bath, detach the condenser and transfer the contents of the flask to a 250 ml. separating funnel washing in with 50 ml. of water in all. Rinse the flask with 50 ml. of ethyl ether (sp. gr. 0·720 to 0·724), and pour the ether into the funnel. Stopper the funnel and shake vigorously while the contents are still slightly warm and allow the funnel to stand until the two layers of liquid separate and clarify. Draw off the aqueous alcoholic layer into the flask used for the saponification and pour the ethereal layer from the top of the funnel into a second 250 ml. separating funnel containing 20 ml. of water. Extract twice more in the same way the aqueous alcoholic soap solution, each time with 50 ml. of ether and combine the three extracts in the second funnel. If the extracts contain solid suspended matter pass them through a small dry fat-free filter into the second separating funnel, washing the filter subsequently with ether.

Rotate the extracts gently in the second funnel, with 20 ml. of water and, after allowing to separate, run off the wash water.

If the presence of metallic soaps in the linseed oil be suspected, combine the ether extracts in a second dry funnel, without adding the 20 ml. of water. Shake the extracts therein with 5 drops of concentrated hydrochloric acid. Whether metallic soaps are present or not wash the ethereal solution twice with 20 ml. of water shaking vigorously each time. Then successively wash with 20 ml. of N/2 aqueous potassium hydroxide, 20 ml. of water, 20 ml. of N/2 aqueous potassium hydroxide, and at least twice more with 20 ml. of water. Continue washing until the wash water no longer turns pink on addition of phenolphthalein solution.

Transfer the ethereal solution to a weighed flask and evaporate to small bulk. Add 2 ml. to 3 ml. of acetone and completely remove the solvent from the flask by means of a gentle current of air, the flask being almost entirely immersed in boiling water and rotated at an oblique angle. Dry the flask and contents to constant weight at a temperature not exceeding 80° C.

Dissolve the contents in 10 ml. of freshly boiled and neutralised 95 per cent. alcohol and titrate with N/10 alcoholic sodium hydroxide solution, using as indicator, phenolphthalein.

If the titration so obtained does not exceed 0·1 ml. calculate the proportion of unsaponifiable matter in the linseed oil from the weight of the residue obtained, by dividing this by the weight of linseed oil taken and multiplying by 100, but if the titration exceeds 0·1 ml. the test shall be repeated from the beginning.

GIVEN under my Official Seal this 23rd day of December, 1949.

DANIEL MORRISSEY,

Minister for Industry and Commerce.