Restoring a mirror: A method of re-silvering
By Josh Schaffer
By Josh Schaffer
Currently on my bench is an early 20th century mirror that is in need of new silvering. Manufactured by Mappin and Webb in the year 1913-1914, these types of mirrors were mass produced. Though in good condition, it had been immersed in silver dip to try and clean the silver. This reacted with the silvering badly and turned it black.
My job was to re-silver the glass and hopefully see my reflection by the end of it.
After researching various recipes and watching others re-silver on YouTube, I came across a method that seemed promising.
Yes, the creepy distorted voice seemed a bit much; however, the method in which he/she was explaining fit an exact recipe from 1911, written by Heber Curtis, titled "Methods of Silvering Mirrors".
Essentially, a concoction to silver a mirror involved: silver nitrate, sodium hydroxide, ammonia, and sugar. All of these things were readily available in the workshop, so I decided to give it a go.
The first step was to take off the backing that protected the silvering. This was done by taking some cotton, dipping it in industrial methylated sprits, and wiping the backing off.
This was done by taking some cotton, dipping it in industrial methylated sprits and wiping the backing off.
By looking at Heber Curtis's publication, diluted nitric acid would be able to take off the silvering and prepare the glass for the concoction that I would applying.
As directed by Curtis, I prepared the solution as follows: taking one gram of silver nitrate and one gram of sodium hydroxide, I added enough water to completely dissolve them. I poured them into a glass beaker, where the colour changed to black. I added around 30 drops of ammonia until the solution turned clear. Next I added four grams of sugar and mixed. Under a hot plate, I stirred the solution and it began to turn black, which, according to Curtis and the distorted voice, was a good sign.
I placed the mirror into a shallow pan, poured the solution in and waited for magic to happen.
Sure enough, after three minutes, silver began to precipitate on the surface and my reflection occurred.
After 15 minutes I was satisfied with the appearance and rinsed the glass off with water. Once I reassembled the mirror I noticed that there was still some minor sections that hadn't been silvered completely (see following image).
This was solved by placing silver Mylar™ behind the glass which just help hide those areas.
Let me know what you think!