A second silvering attempt yielding a better result
Today we silvered with Raphaël his 12” f/3.9 mirror I recently finished. It worked very well and way better than my last attempts. What we changed was the cleaning process (more thorough) and the ambient temperature for the reaction (25ºC).
Cleaning procedure :
- Acetone cleaning of the whole optical surface, edge and bevel
- Rinse with deionized water
- Chalk with water (dense, like whole milk), scrub until there’s no dry spot left
- Rinse with the garden hose, high pressure
- Chalk with water (thinner, like no-fat milk), scrub until no dry spots
- Rinse with the garden hose, high pressure
- Chalk with water, thin (milk + water)
- Rinse with the garden hose, high pressure
- Rinse with a LOT of deionized water
- Spray silver (using the recipe detailed here)
The reaction worked so well that a silver deposit formed even on non-cleaned surfaces such as the plastic tub we were spraying the mirror in.
We still didn’t sensitize the surface as the safety sheet for stanneous chloride does not make me want to touch it. The coating was great except for a bit of darkening at the edge, but that’s expected since the bevel is only rough ground. That’s an error I made on this mirror.