Title: Method for etching shadow mask and regenerating etchant

Abstract: This disclosure depicts a novel method of etching a shadow mask for a color television picture tube and in particular to a method of etching the steel substrate layer of a two layer shadow mask, wherein the first layer has been previously etched, and of reclaiming the used etchant. Ferric sulphate is used to etch the steel substrate layer, resulting in the generation of ferrous sulphate, a by-product of the chemical reaction of the ferric sulphate etchant and the steel substrate. The used etchant is reclaimed by reacting and mixing in a particular manner the used etchant with sulfuric acid and hydrogen peroxide.

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Inventors: Lerner, Martin (River Forest, IL, US)

Application Number: 591735
Filing Date: 1975-06-30
Publication_date: 1976-06-08
Assignee: Zenith Radio Corporation (Chicago, IL)
Primary Class(es): 216/12 134/10, 216/93, 216/108
Other Classes:
US Patent Ref:

3526560	Sep, 1970	Thomas	134/10.
3574013	Apr, 1971	Frantzen	156/8.
3775202	Nov, 1973	Meek et al.	156/19.
3880685	Apr, 1975	Rehm et al.	156/345.

Other Refs:
Primary Examiner: Powell, William A.
Assistant Examiner: Leitten, Brian J.
Attorney: Garrett; John R.