IS 388 : 2024/ISO 423 : 1994 Hydroquinone, Photographic Grade - Specification
NATIONAL FOREWORD
This Indian Standard (Fourth Revision) which is identical to ISO 423 : 1994 'Photography - Processing chemicals - Specifications for hydroquinone' issued by the International Organization for Standardization (ISO), was adopted by the Bureau of Indian Standards on the recommendation of the Electroplating Chemicals and Photographic Materials Sectional Committee and approval of the Chemical Division Council.
This standard was first issued in 1952 as a tentative standard and subsequently revised in 1963, incorporating modifications in the requirements for hydroquinone content, melting point and iron content. Changes were also made in the methods of sampling and test. The second revision of this standard was brought out in 1972 modifying the requirements for description and solubility in dilute acetic acid. The third revision of this standard was brought out in 1999 modifying the requirement for heavy metals along with the test method, the requirement for 'sulphated ash' was substituted by 'residue on ignition' and the relevant test method was also incorporated. An alternate method for hydroquinone determination was also incorporated.
Now this standard is being revised by adopting ISO 423 : 1994 on dual number basis.
The text of the ISO standard has been approved as suitable for publication as an Indian Standard without deviations. Certain conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following:
a) Wherever the words 'International Standard' appear referring to this standard, they should..be read as 'Indian Standard'; and
b) Comma (,) has been used as a decimal marker, while in Indian Standards the current.. practice is to use a point (.) as the decimal marker.