Re: Speculum Metal ??
Dean Ketelsen (ketelsen@as.arizona.edu)
Wed, 12 Apr 1995 14:15:53 -0700
With the apparent interest in silvering glass mirrors (and the associated
danger), you might want to know that you can get a reasonable spray-on
silver coat without the dangerous chemicals, in only a few minutes and
for very few dollars. Now an unprotected silver coating does not last
long in the field, but for shop tests involving multiple reflections,
as in null testing a parabola against a flat, it kicks the reflectivity
up in the 80-some percent range to make the testing a lot easier. We did
our club's 30 inch mirror this way, and another shop did a 60" test sphere
and were able to use it for over a year before they recoated it.
I don't have all the info in front of me, but you _clean_ your part,
wet it with distilled water, followed by a sensitizer bath, then you
spray on a two part solution (plant sprayer in each hand - two containers)
and in a few seconds - a silvered surface. Will look up the process and
chemical source and send it along tomorrow if there is any interest.
-Dean