[DanielS]

My company has recently moved their entire operations from Australia to the United States.  They used to always use Decon-90 to clean their glassware that is used in the synthesis of polymers (inorganic).  An alkali bath was prepared with 5% Decon-90 and glassware was allowed to soak no longer than overnight to prevent etching.  The problem is here in the states Decon-90 is not readily available.  I know that contrad-70 is the same stuff with a different name but the cost is a issue.  According to Alconox, their product Liquinox is a suitable substitute for Decon90/contrad70; however, the operating pH is different.  Liquinox is around 8.5 and decon-90 is around 11.  We had a small stock of Decon-90 that was brought here with them when they moved but it is all gone now.  I have since been using Liquinox (a 1% solution) and it doesn't seem to do the job.  I was wondering if anyone else out their has had this problem or has any suggestions.

A few ideas I had were:
1.) Add some sodium hydroxide to raise the pH.
2.) Possibly increase the concentration of Liquinox

Thank you for the help.

[Arkcon]

Depending on the chemistry of the polymers in question, pH may be more important than detergent in dispersing adhesion to the glass.  I'd guess any surfactant can lower the surface tension and help things float free, but pH may disrupt the structure of the polymer, or compete with charged sites, or even mildly alter the glass surface so the polymer is released.  Use base to match the pH, for starters.

[DanielS]

That's what I am trying first.  I have added enough sodium hydroxide to get the bath to a pH of around 10.  I have a few junk pieces of glassware to test for etching.  We'll see how it works.  If there is no etching after 24 hours I will probably leave the glassware in there to see how long it takes to etch.  Even though we only leave glassware in the bath 24 hours maximum, it would be nice to know how long until it etches.  Our polymers are all silicone based, primarily siloxanes.