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    Re: sextant replacement mirror
    From: John Huth
    Date: 2010 May 4, 13:36 -0400
    George - 

    Robert E. White

    http://www.robertwhite.com/aboutus.html

    fixed up my sextant for me.   On the other hand, it sounds like a fun project if you want to do it yourself.

    John H. 

    On Tue, May 4, 2010 at 12:26 PM, Douglas Denny <douglas.denny@btopenworld.com> wrote:

    Or, I'll silver it for you - so long as it is a 'one-off' - to get another dead sextant into good working order. (I do not want to be inundated with requests to silver mirrors).
    -----------

    Silvering is quite easy so long as you have the materials and are careful with cleaning the glass surface. It is based on Brashear's method.(or Tollen's reagent - similar).

    You need:- silver nitrate; conc.(0.88) ammonia solution; glucose; sodium hydroxide; de-ionised water.

    and for cleaning: degreasing solvents: eg; carbon tetrachloride; methyl ethyl ketone; acetone; conc. nitric acid.
    best if possible: finishing with conc. sulphuric acid and potassium dichromate solution.

    I'll describe the method and concentrations of solutions if anyone requests it.

    Douglas Denny.
    Chichester. England.


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