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In conventional stop baths, the acid ingredient which stops development is hazardous, unpleasant to use and can damage prints.

Acid can break down print sizing which normally protects fibers from fixer thiosulfate contamination, a major cause of deterioration. Plain water stop baths eliminate the side-effects of acid, but do not stop development as effectively, and can cause stains, emulsion swelling and reticulation.

BLOCK is an acid solution, but the acids are buffered to minimize side-effects. Buffering protects print fibers for greater permanence, reduces emulsion swelling, staining, reticulation and eliminates odors. BLOCK will also prevent carbonate gas ruptures of films (pinholes) when used as directed.

BLOCK is the basic stop bath for all SPRINT™ SYSTEMS processes. Always use BLOCK Stop Bath before fixing with RECORD Alum Hardening Converter to provide the correct acid value.

One liter of BLOCK Stop Bath concentrate will make 10 liters of working solution, enough to process (600) 8×10 fiber prints or (900) 8×10 resin-coated prints or (600) rolls of 35mm, 36 exposure film.