Journal of the Society of Motion Picture Engineers ( Volume: 42, Issue: 1, January 1944)

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A Review of Hypo Testing Methods

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Publisher: SMPTE
Doc Type: Journal Article
Article Type: research-article
Abstract: The degree of washing of photographic films and prints is usually determined by estimating the hypo content of either (a) the photographic material, (b) the wash water, or (c) the drippings collected from the material. Various hypo testing methods are described including the use of either potassium permanganate, iodine, mercuric chloride, silver nitrate, or electrical conductivity measurements. It is shown that chemical or electrical measurements of the hypo content of wash water, or drippings from washed photographic materials, do not give an accurate indication of the quantity of residual hypo in the film or print but may be used for control purposes with continuous processing machines. Spot tests made on the surface of the material with iodine solutions, e. g., iodineazide-starch, are not easily reproducible with respect to the ratio of the volume of test solution to the area of the film or print to which it is applied. Bathing tests in which the film or print is immersed in the test solution, e. g., iodineazide-starch, are reproducible with respect to volume of reagent and the area treated but do not measure the total residual hypo in the material. Chemical and electrical conductivity measurements of hypo in the wash water, etc., the spot test methods and the. bathing tests may be used, however, for control purposes to indicate the degree of washing if they are first standardized by a testing method which determines the hypo content of the film or print quantitatively, that is, the total residual hypo. The total residual hypo in films may be determined quantitatively by use of the Crabtree-Ross mercuric chloride test and in prints by a silver nitrate test which involves the conversion of hypo to silver sulfide in situ and estimating the silver sulfide by (a) measurement of the transmission density of the silver sulfide stain, and then reading the corresponding residual hypo content from a standard curve, or (b) matching the silver sulfide stain produced by a drop of silver nitrate with a series of standard stains.
Publication Date: 1944-01-01
DOI: 10.5594/J08461
Link: https://doi.org/10.5594/J08461
Author(s): J. I. Crabtree, G. T. Eaton, L. E. Muehler

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J. I. Crabtree, G. T. Eaton, and L. E. Muehler; A Review of Hypo Testing Methods, Journal of the Society of Motion Picture Engineers ( Volume: 42, Issue: 1, January 1944); SMPTE, 1944. Available at https://doi.org/10.5594/J08461

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J. I. Crabtree, G. T. Eaton, and L. E. Muehler; A Review of Hypo Testing Methods, Journal of the Society of Motion Picture Engineers ( Volume: 42, Issue: 1, January 1944); SMPTE, 1944. Available at https://doi.org/10.5594/J08461

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<span class="citation">J. I. Crabtree, G. T. Eaton, and L. E. Muehler; <cite>A Review of Hypo Testing Methods</cite>, Journal of the Society of Motion Picture Engineers ( Volume: 42, Issue: 1, January 1944); SMPTE, 1944. Available at <a href="https://doi.org/10.5594/J08461" target="_blank" rel="noopener">https://doi.org/10.5594/J08461</a></span>

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J. I. Crabtree, G. T. Eaton, and L. E. Muehler; <cite id="bib-10-5594-j08461">A Review of Hypo Testing Methods</cite>, Journal of the Society of Motion Picture Engineers ( Volume: 42, Issue: 1, January 1944); SMPTE, 1944
<span class="doi">10.5594/J08461</span>
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