S.I. No. 161/1949:

STANDARD SPECIFICATION (KNOTTING) ORDER, 1949.

STANDARD SPECIFICATION (KNOTTING) 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 (Knotting) 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 16 : 1949.

SCHEDULE.

PART I.

KNOTTING.

PART II.

SPECIFICATION.

In this specification, the letters I.S., when followed by two sets of numbers, refer to the Irish Standard of which the first is the serial number and the second the year of its promulgation by the Minister for Industry and Commerce.

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 knotting required in the preparation of joinery to provide an impervious covering for knots and other resinous areas liable to stain superimposed paint.

DESCRIPTION.

2. The knotting shall be a uniform dispersion of lac or other suitable resin in a suitable solvent. It shall produce a film which is unaffected by the natural solvents present in resinous knots or by the solvents commonly used in paints and shall be of such consistency that it will work under the brush.

APPEARANCE.

3. Apart from the turbidity natural to lac solutions, the knotting shall be free from visible aggregates and foreign matter.

SOLID CONTENT.

4. The solid content of the knotting, when determined in the manner described in Appendix A, shall be not less than 30 per cent.

DRYING.

5. A film of the knotting, prepared in the manner described in Appendix B, shall be bright and free from tackiness after it has been dried for 30 minutes in a nearly vertical position at a temperature of 65° F. to 70° F.

BLEEDING.

6. When tested by the method described in Appendix C, the coat of white paint applied over the film of the knotting shall show no greater discolouration or become in any way inferior to the coat of white paint applied over the film of standard lac solution.

STAIN PREVENTION.

7. When tested by the method described in Appendix D, a film of the knotting shall prevent staining of the coat of white paint not less effectively than a film of the standard lac solution.

RESISTANCE TO PAINT SOLVENTS.

8. When tested by the method described in Appendix E, a film of the knotting shall show no greater softening or disturbance than a film of the standard lac solution.

STANDARD LAC SOLUTION.

9. The standard lac solution referred to in this specification shall be made by dispersing 4 lbs. of lac, conforming to B.S. 954 : 1941, in 1 gal. of industrial methylated spirits, 64 over proof, to form a uniform varnish, free from aggregate.

SAMPLING AND SIZE OF SAMPLES.

10. Representative samples, each measuring not less than 1 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.

APPENDIX A.

Method for the Determination of Solid Content.

Five grams of the knotting shall be weighed out in a flat-bottomed dish of convenient size and the dish and contents placed on a steam bath. When the volatile spirit is almost all removed, the dish shall be transferred to a suitable oven and maintained for two hours at a temperature of 98° C. to 102° C. It shall then be allowed to cool to air temperature in a desiccator and weighed. The residue shall be calculated as a percentage of the original weight of the knotting.

APPENDIX B.

Preparation of Film for Testing.

The film of the knotting shall be prepared by applying the knotting by brush to a strip of glass plate 6 in. by 4 in. at a spreading rate of not more than ½ oz. per sq. yd. at a temperature of 65° F. to 70° F. and allowing it to dry in a nearly vertical position for 30 minutes.

APPENDIX C.

Method of Testing Bleeding.

A film of the knotting shall be applied to a strip of glass as described in Appendix B and allowed to dry for 30 minutes. A film of standard lac solution shall be prepared in the same manner and at the same time.

A coat of white lead paint, conforming to B.S. 261 : 1936, shall then be applied to each film, the spreading rate on each film being the same. After drying for 16 hours at 65° F. to 70° F. the two painted films shall be stoved for 2 hours at 110° F. to 120° F. After standing for 7 days the two paint films shall be compared.

APPENDIX D.

Method of Testing Stain Prevention.

A film of the knotting shall be applied in the manner described in Appendix B to a bitumen surface and shall be allowed to dry for 30 minutes. A film of standard lac solution shall be applied in the same manner and at the same time to another bitumen surface. A coat of white lead paint, conforming to B.S. 261 : 1936, shall then be applied to each film at the same spreading rate. After drying for 16 hours at 65° F. to 70° F. the appearance of the two paint films shall be compared.

The bitumen surface for the test shall be obtained by casting in a mould, blown bitumen having a softening point of 230° F. to 250° F., and a penetration of 10 to 20.

APPENDIX E.

Method of Testing Resistance to Paint Solvents.

A film of the knotting shall be applied to a strip of glass as described in Appendix B. A film of the standard lac solution shall be applied in the same manner and at the same time.

After drying for 30 minutes, the two coated plates shall be suspended for 24 hours in a mixture of equal volumes of white spirit conforming to I.S. 11 : 1949 and of turpentine conforming to I.S. 12 : 1949.

The two films shall then be compared.

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

DANIEL MORRISSEY,

Minister for Industry and Commerce.