plating, anodizing, & finishing Q&As since 1989
Mixing the chrome tank
We have a decorative chrome (hexavalent chromium with catalyst) and We mix the bath solution in order to maintain a homogeneous bath temperature but while doing this barium sulphate and the sludge coming from the anodes ,which are already settled down, also mix through the solution. Does this affect anything?
- Izmir, Turkey
While your chrome bath requires mixing or agitation to prevent temperature stratification, it may also require mixing for catalyst regulation.
While a 'straight sulfate', 'conventional' chromic-sulfuric bath requires a 100:1 ratio of chromate to sulfate, the 'mixed catalyst', 'self regulating' baths use a partially soluble fluosilicate catalyst which self-regulates by settling out when too much is added, and going back into solution when needed. These baths require periodic mixing so the fluosilicate precipitate can redissolve when it is needed.
If this is the bath you are using, stirring or hoeing is indispensable--you are supposed to stir up the sludge.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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