Aug 2, permanent change in standard pre-furnace clean

Uli Thumser uthumser at
Mon Aug 1 11:08:11 PDT 2011

Dear wbdiff users:

We would like you to be aware of upcoming changes in the standard 
pre-furnace clean procedures.
We've made a reservation tomorrow, August 2nd from 10 AM to 12 PM.
Instead of the 4:1 sulfuric-peroxide/HCl-SC2/HF dip sequence that has 
been standard at SNF for many years, we are going to use a standard RCA: 
SC1/SC2/HF dip.
SC1 consists of 5:1:1 H2O/H2O2/NH4OH (Ammonium Hydroxide).
The SC1 bath must be changed every four hours and the addition of H2O2 
is allowed, much the same as the SC2 bath, 5:1:1 H2O:H2O2:HCl.  The bath 
temperature is 50C and the time remains 10 minutes.
Note: today we replaced already two rows of sulfuric acid with Ammonium 
Hydroxide in the right chemical passthrough. Ammonium Hydroxide is no 
longer in the left passthrough.

SNF staff

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