S.I. No. 43/1950 - Standard Specification (Varnish) Order 1950.

S.I. No. 43 of 1950.

STANDARD SPECIFICATION (VARNISH) ORDER 1950.

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 (Varnish) Order, 1950.

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 10: 1950.

SCHEDULE.

PART I.

VARNISH.

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.

DESCRIPTION.

1. The varnish covered by this specification shall be clear, transparent and suitable for use as indicated below, and when dry shall give a uniform and glossy coating free from runs and specks. It shall be one of the following distinguished in respect of type and colour, and specified as :

A. interior oil varnish :—suitable for use on interior work.

A-1. Extra pale.

A-2. Pale.

A-3. Ordinary.

B. exterior oil varnish :—suitable for use on exterior work.

B-1. Extra pale.

B-2. Pale.

B-3. Ordinary.

C. flatting or rubbing oil varnish :—suitable for use as an undercoat or flatting varnish.

C-1. Pale.

C-2. Ordinary.

D. extra hard-drying varnish :—suitable for use where a hard, non-softening finish is required.

D-1. Pale.

D-2. Ordinary.

COLOUR.

2. For varnish of the types A-1, A-2, B-1, B-2, C-1, and D-1, the material shall not be darker in colour than the appropriate standard solution as described below, when compared in similar glass tubes 1 cm. (0·39 in.) in diameter and about 10 cm. (approximately 4 in.) long, by viewing them transversely by transmitted light.

For varnish of the types A-3, B-3, C-2, and D-2 no limiting standard of colour is specified except that the material shall be transparent when viewed transversely by transmitted light in a glass tube of the dimensions specified above.

Standard Solutions : The standard solutions for colour comparison are made as follows:—

(i) For Varnish of the Types A-1 and B-1 : a freshly made solution of iodine (0·10 g.) and pure potassium iodide, free from iodate, (1 g.), in water (100 ml.).

(ii) For Varnish of the Types A-2 and B-2 : a freshly made solution of iodine (0·25 g.) crystallised nickel sulphate (6·8 g. : NiSO₄.7H₂O.) and pure potassium iodide, free from iodate, (3 g.), in water (100 ml.).

(iii) For Varnish of the Types C-1 and D-1 : a freshly made solution of iodine (0·15 g.) and pure potassium iodide, free from iodate, (1·5 g.), in water (100 ml.).

Readings on the Lovibond Scale corresponding to the standard solutions specified above are given in Appendix A.

DRYING TIME.

3. Varnish of the types A-1, A-2, A-3, C-1, C-2, D-1 and D-2 shall become " surface dry " in not more than six hours and " hard dry " in not more than 18 hours when tested by the method described in Appendix B.

Varnish of the types B-1, B-2, and B-3 shall become " surface dry " in not more than 8 hours and " hard dry " in not more than 18 hours when tested by the method described in Appendix B.

For the purpose of this clause the terms " surface dry " and " hard dry " shall have the meanings given in Note 1 and Note 2 respectively of Appendix B.

VOLATILE MATTER.

4. The loss in weight on heating the material in the manner described in Appendix C shall not exceed 50 per cent.

VISCOSITY.

5. The viscosity of the material shall not be more than 5·5 poise at 15°C. or less than 1·8 poise at 25°C.

For the purpose of this specification the methods for the determination of viscosity given in B.S. 188 :1937 "Method for the Determination of the Viscosity of Liquids in Absolute (C.G.S.) Units " shall apply.

Where an approximation of the viscosity is required the method of Appendix H may be used.

Note 1.—The term " poise " which is the unit of viscosity in the metric system, is defined as the viscosity of a fluid in which I dyne is the tangential force on 1 sq. cm. of either of two parallel planes separated by 1 cm., one of which moves in its own plane with a velocity relative to the other of 1 cm. per sec., turbulence being absent. The viscosity of distilled water at 20°C. is 0·01005 poise or approximately 1 centipoise.

WEBBING.

6. The material shall not " web " or wrinkle when tested in the manner described in Appendix D.

FLEXIBILITY AND ADHESION—TYPES A and B.

7. A film of the material prepared and tested in the manner described in Appendix E shall not become visibly damaged or detached.

FLATTING AND RUBBING PROPERTIES—TYPE C.

8. A film of the material prepared and tested in the manner described in Appendix F shall be such that it is suitable for flatting or rubbing down, and it shall not "sweat up ", that is, change in appearance when compared with a freshly flatted surface, during the period of test.

HARDNESS OF FILM—TYPE D.

9. A film of the material prepared and tested in the manner described in Appendix G shall satisfy the conditions as to hardness therein specified.

SAMPLING AND SIZE OF SAMPLES.

10. 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, and shall be packed in clean, dry, airtight, non-absorbent containers made of material on which the sample has no action. The containers shall be of such size that they are nearly filled by the sample. Each sample container so filled shall be sealed and shall be marked with the date of sampling and with sufficient information to identify the sample.

APPENDIX A.

Readings on the Lovibond Scale Corresponding to the Standard Solutions Specified for Colour.

The following units on the Lovibond Scale which correspond to the standard solutions specified for colour comparison are given for the convenience of those users who have a Lovibond instrument :

(a) For Varnish of the Types A-1 and B-1 : a combination of 5·1 red and 49·1 yellow units with two colourless glasses in front of the material.

(b) For Varnish of the Types A-2 and B-2 : a combination of 11·7 red and 76·0 yellow units.

(c) For Varnish of the Types C and D : a combination of 9·3 red and 65 yellow units with three colourless glasses in front of the material.

APPENDIX B.

Method for the Determination of Drying Time.

One coat of the varnish shall be applied to a previously cleaned tinplate strip 15 cm. x 5 cm. (about 6 in. x 2 in.) and 0·030 cm. (0·012 in.) in thickness in the manner described in Appendix D, paragraph (c), and in such quantity as to produce a uniform film weighing, when dry, approximately 25·5 g. per sq. metre (¾ oz. per sq. yd.). The panel shall then be allowed to dry in a horizontal position in a well ventilated room at 16°C. to 20°C. so as to expose the film to diffused daylight for at least six hours during the drying period, but care shall be taken to protect it from exposure to direct sunlight.

Note 1.—For the purpose of this test the term " surface dry " implies a condition such that clean, dry, silver sand (graded so as to pass a No. 52 British Standard Test Sieve, conforming to B.S. 410 :1943, but to be retained on a No. 100 British Standard Test Sieve), which has been sprinkled on to the surface of the varnish film and allowed to remain there for about one minute, can be removed by means of a camel hair brush without injury to the varnish film.

The term " hard dry " implies a condition such that after slight rubbing down a second coat of the varnish can be satisfactorily applied.

Note 2.—The period of 18 hours is adopted for convenience in carrying out the " hard dry " test in order to secure in winter time the specified exposure of the varnish film to daylight. By arrangement between the purchaser and vendor an alternative time period may be substituted.

APPENDIX C.

Method for the Determination of Volatile Matter.

The material (1·0 g. to 2·0 g.) shall be weighed into a flat-bottomed, circular, metal dish about 7·6 cm. (3 in.) in diameter. The dish and contents shall then be heated in a suitable oven at 105°C. to 110°C. for 3 hours, allowed to cool to air temperature and re-weighed.

APPENDIX D.

Method of Test for Webbing.

Glass-plates (e.g., microscope slides) shall be coated on one side with the material to be tested and drained vertically for half-an-hour. The plates shall then be placed upon strips of cardboard of the same size on the shelf of a suitable oven and maintained at a temperature of about 38°C. until the film is dry.

A suitable oven is a copper air oven 15 cm. x 15 cm. x 15 cm. (6 in x 6 in. x 6 in.) having a hole of 2·5 cm. to 3 cm. (1·0 in. to 1·25 in.) in diameter in the middle of its floor and containing a perforated copper shelf placed centrally. At the top of the oven are two tubulures about 1·3 cm. (0·5 in.) in diameter, one of which is left open while the other is furnished with a cork through which a thermometer passes so that its bulb reaches the central shelf.

A small burner, 0·4 cm. (0·16 in.) in internal diameter, burning coal gas and giving a luminous flame 1·3 cm. (0·5 in.) high is placed underneath the hole in the oven floor at such a distance that the tip of the flame is about 8·25 cm. (3·25 in.) below the plane of the floor. By this means a temperature of about 38°C. will be maintained at the shelf of the oven, when the outside temperature is about 14°C.

APPENDIX E.

Method of Test for Flexibility—Types A and B.

One coat of the varnish shall be applied on a previously cleaned tinplate strip 15 cm. x 5 cm. (about 6 in. x 2 in.) and 0·030 cm. (0·012 in.) in thickness, in the manner described in paragraph (c) below, and in such quantity as to produce a uniform film weighing, when dry, approximately 25·5 g. per sq. metre (¾ oz. per sq. yd.).

As certain qualities of tinplate are liable to show surface crack on bending, a blank determination should also be made.

The panel shall then be allowed to dry in a horizontal position for 24 hours at 16°C. to 20°C. protected from dust, and shall thereafter be heated for two hours in an oven at 95°C. to 98°C.

(a) With Interior Oil Varnish the panel shall be removed from the oven at the end of this time, and kept at room temperature for one hour. Then, with the varnish film outside, it shall be bent double, at a distance of 7·6 cm. (3 in.) from either end, over a rod 0·952 cm. (0·375 in.) in diameter, care being taken that the temperature of the specimen and the rod during this operation does not exceed 16°C.

The time occupied for the actual bending shall not exceed one second. A suitable apparatus for carrying out the test is shown in Fig. 1.

(b) With Exterior Oil Varnish the panel shall be removed from the oven at the end of this time, and shall be placed in an ice chest and allowed to remain at 0°C. for two hours. This can be conveniently carried out by fixing the panels to the inner sides of a metal box, which is then placed in contact with the ice. The specimen, whilst still in the ice chest, shall then be bent double, at a distance of 7·6 cm. (3 in.) from either end, over a rod 0·635 cm. (0·25 in.) in diameter, care being taken that the temperature of the specimen and rod during this operation does not exceed 0°C.

The time occupied for the actual bending shall not exceed one second. A suitable apparatus for carrying out the test is shown in Fig. 1.

(c) Method of obtaining uniform film.—The tinplate strip after being cleaned with cotton-wool moistened with benzene shall be weighed. The sample of varnish shall then be rapidly but carefully brushed on to one side of the strip and rapidly re-weighed. By means of the brush, varnish shall be added to or removed from the film until the weight of the wet film, as determined by rapid trial weighings, is such as will produce a dry film of the weight required.

Example : If the sample of varnish contains 45 per cent. of non-volatile matter the amount to be brushed on to one side of the 15 cm x 5 cm. tinplate, as determined by trial weighings of the wet film, would be :

If the non-volatile matter present in the sample varies from 45 per cent., the weight of the wet film required may be calculated accordingly.

The weight of the dried film shall be ascertained and can be accepted as satisfactory for the test if the weight per unit area does not vary by more than 10 per cent. from 25·5 g. per sq. metre.

APPENDIX F.

Method of Test for Flatting or Rubbing Properties—Type C.

A film of the varnish shall be obtained and dried for a period of 18 hours in the manner described in Appendix B. It shall then be rubbed with fine pumice powder (graded so as to pass a No. 240 British Standard Test Sieve conforming to B.S. 410 : 1943) and water, using a felt pad, with long, even, firm strokes, to and fro, in varying directions but not in circles. A smooth dull surface shall result from this treatment even where dust particles have become embedded in the film. No spots shall appear in those places in which the pumice powder has been ground into the film and become attached.

After the rubbing down operation, the panel shall be kept for 24 hours at 16°C. to 20°C. during which period the film shall not " sweat up ", that is, change in appearance, when compared with a freshly flatted surface.

APPENDIX G.

Method of Test for Hardness of Film—Type D.

One coat of the varnish shall be applied to a previously cleaned tinplate strip 15 cm. x 5 cm. (about 6 in. x 2 in.) and 0·030 cm. (0·012 in.) in thickness, in the manner described in Appendix E, paragraph (c), in such quantity as to produce a uniform film weighing, when dry, approximately 25·5 g. per sq. metre (¾ oz. per sq. yd.).

The panel shall then be allowed to dry in a horizontal position for 3 days at 16°C. to 20°C.

The film shall be considered satisfactory at the end of this period if

(a) pressure exerted between the thumb and finger does not move the film or leave any mark which remains noticeable after the spot is lightly polished.

(b) the film does not powder when rapidly rubbed with the finger.

APPENDIX H.

Determination of Viscosity by Bubble Tube Method.

For practical purposes only, it is convenient to estimate the approximate viscosity of a sample under test by comparison with other liquids which may be standard glycerine solutions as described below, or oils of known viscosity.

The comparison may be made by comparing the time of travel of an air bubble in suitable tubes containing the liquids under strictly similar conditions. The tubes may conveniently be 10 mm. in diameter so long as the variation in internal diameter is not greater than 0·1 mm. The tubes may be placed vertically or inclined at an angle so that the bubble rises more slowly.

Note.—Diluted glycerine of density 1·2467 at 15°C. has a viscosity of 5·5 poise at 15°C.

Diluted glycerine of density 1·2403 at 15°C. has a viscosity of 1·8 poise at 25°C.

GIVEN under my Official Seal this 20th day of February, 1950.

DANIEL MORRISSEY,

Minister for Industry and Commerce.