Journal of the Society of Motion Picture Engineers ( Volume: 43, Issue: 6, December 1944)

[ACTIVE]

Calcium Scums and Sludges in Photography

Metadata

Publisher: SMPTE
Doc Type: Journal Article
Article Type: research-article
Abstract: Calcium salts may be introduced into photographic processing solutions from (a) the water supply, (b) the emulsion, or both, and these salts combine with some of the developer constituents to form insoluble compounds which may appear as (1) a sludge suspended in the developer or accumulated on the filters, (2) a scum on the film, or (3) a scale on rollers, sprockets, racks, and the walls of tanks. The control of the water supply will reduce the quantity of these precipitates and the scum may be removed by suitable acid rinse or acid fixing baths, but calcium-sequestering agents are often used for more complete control. When selecting these agents, their calcium-sequestering power, stability, photographic effect, and their effect when carried over into the fixing bath must be considered, and on the basis of these requirements, sodium tetraphosphate was found the most suitable.† Appropriate quantities of sodium tetraphosphate added to the developer were found to (1) prevent sludge formation in mixing, storing, or use of the developer, (2) prevent the formation of scum on the film when in the developer, and (3) greatly diminish the rate at which incrustations accumulate on the tank walls, sprockets, and mechanical parts. If developers are stored at high temperatures, the polyphosphates present tend to hydrolyze to the simple phosphates which, when carried over into the fixing bath, may precipitate as aluminum phosphate. This hydrolysis does not occur on storage of the dry solids and only very slowly below 85 F when in solution. Solutions stored at high temperatures or for prolonged periods may be protected by the addition of sodium citrate which extends the life of the tetraphosphate solution and prevents precipitation in the fixing bath if hydrolysis has occurred.
Publication Date: 1944-12-01
DOI: 10.5594/J07990
Link: https://doi.org/10.5594/J07990
Author(s): R. W. Henn, J. I. Crabtree

Source Data (JSON)

Full registry record with provenance metadata. Open directly: /api/doc/10.5594-J07990.json

Reference this Doc

Plain text (ISO 690 compliant)

Preview:

R. W. Henn and J. I. Crabtree; Calcium Scums and Sludges in Photography, Journal of the Society of Motion Picture Engineers ( Volume: 43, Issue: 6, December 1944); SMPTE, 1944. Available at https://doi.org/10.5594/J07990

Snippet:

R. W. Henn and J. I. Crabtree; Calcium Scums and Sludges in Photography, Journal of the Society of Motion Picture Engineers ( Volume: 43, Issue: 6, December 1944); SMPTE, 1944. Available at https://doi.org/10.5594/J07990

HTML (ISO 690 compliant)

Preview:

Snippet:

<span class="citation">R. W. Henn and J. I. Crabtree; <cite>Calcium Scums and Sludges in Photography</cite>, Journal of the Society of Motion Picture Engineers ( Volume: 43, Issue: 6, December 1944); SMPTE, 1944. Available at <a href="https://doi.org/10.5594/J07990" target="_blank" rel="noopener">https://doi.org/10.5594/J07990</a></span>

SMPTE's HTML Pub

Preview:

R. W. Henn and J. I. Crabtree; Calcium Scums and Sludges in Photography, Journal of the Society of Motion Picture Engineers ( Volume: 43, Issue: 6, December 1944); SMPTE, 1944
doi: 10.5594/J07990
url: https://doi.org/10.5594/J07990

Snippet:

<li>
R. W. Henn and J. I. Crabtree; <cite id="bib-10-5594-j07990">Calcium Scums and Sludges in Photography</cite>, Journal of the Society of Motion Picture Engineers ( Volume: 43, Issue: 6, December 1944); SMPTE, 1944
<span class="doi">10.5594/J07990</span>
</li>