Guest Editorial -For Plateworld.com
Don Baudrand, Don Baudrand Consulting, e-mail:firstname.lastname@example.org
Procedure for Silver Plating onto INVAR
The first step is cleaning. Proprietary formula is used. They are composed of sodium hydroxide coupled with specific surfactants and sodium silicate.
The cleaners are discarded and replaced after long usage. Lab testing is determines the right time to discard and make up new. High temperature must be maintained.
Rinsing after cleaning is used with fresh water and flow without accumulation of cleaner.
The next step is the acid treatment and rinse.
For Invar, I recommend sulfamic acid as the best acid treatment because of its chelating ability (Multi-prep 506 for Invar) used at 20% by volume, 3-5 minutes
Temperature 110- 120 degrees F. The range of concentration, time and temperature can vary over a long range and still activate the Invar, and other “difficult to plate alloys”. (HCl, sulfuric acid and other acid treatments have been reported.) (I have tested these and the very best was Multiprep 506.) The acid step is one of the most critical steps to assure good adhesion.
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