Cosmetic repairs to corroded silver

[Andrew McCabe]

I have a number of rare but undesirable silver coins, with surface corrosion and possiblty crystallisation. Examples below.







Does anyone know of any purely cosmetic methods (preferably removable) to make these coins look visually a bit better whilst under my care? Or alternatively some cute photographic techniques to achieve the same effect? On the third coin above I held a black card over the coin whilst photographing it; it seemed to help a lot in removing reflection as earlier attempts were much worse. Believe me, in all three cases, earlier photo attempts looked like a moonscape made of reflective silver! Yet these are ultimately reasonably ok coins for details and wear, so it would be nice if I could just apply a little make-up...

[daverino]

As a reformed "coin improver" myself my inclination is to feel that what you can't fix with a damp Q-tip is best left alone. JMO. Only the upper coin looks to me like it may be crystallized. Usually the surface of a crystallized coin is less reflective than that of regular bright silver. If you can run them under a metal detector crystallized coins will register as less conductive than sound silver - at least that has been my experience.

Regards, Dave

[Jay GT4]

When I "repaired" my Antony Sol denarius I used krazy glue. Once the pieces were dry and in place the coin was still very brittle.  It was so brittle and frail I decided I couldn't ruin it any more so I coated the coin with thin clear coats of Krazy glue.  It actually worked out well.  You can't see the glue on the coin and it sealed it so that it isn't as brittle.  I wouldn't do this on any of my other coins but for this particular one I didn't see the harm since it was in several pieces and in a real state of corrosion.  It smoothed out and filled in all the hairline cracks and it can be removed with acetone (I think).  But if you would like to get rid of that terrible Antony with Armenian Tiara I'd be happy to take it off your hands!  

[Jay GT4]

Here it was before, you can really see the crystallization:

[Andrew McCabe]

When I "repaired" my Antony Sol denarius I used krazy glue. Once the pieces were dry and in place the coin was still very brittle.  It was so brittle and frail I decided I couldn't ruin it any more so I coated the coin with thin clear coats of Krazy glue.  It actually worked out well.  You can't see the glue on the coin and it sealed it so that it isn't as brittle.  I wouldn't do this on any of my other coins but for this particular one I didn't see the harm since it was in several pieces and in a real state of corrosion.  It smoothed out and filled in all the hairline cracks and it can be removed with acetone (I think).  But if you would like to get rid of that terrible Antony with Armenian Tiara I'd be happy to take it off your hands!  

Thanks for the tip but I don't think I'm going to fill in the surfaces of these otherwise valuable imperatorial coins with non-removable glue as I could never sell them as such. I was just curious whether there was another totally removable material that might smooth over the moonscape and enable a prettier photograph - wax for example. I haven't heard about wax being used in this context on silver. Or perhaps just a photographic technique. As noted, a black-card above seemed to improve one coin's photo. Below you can see two photos of the same coin, the top with my normal lighting (shaded daylight) and the bottom with the same but a black card held above the coin. Clearly the lower (black card) photo looks better so I wonder am I on to something regarding a general approach to photographing corroded silver.

[ctgcoins]

Andrew,
A useful photographic trick for shooting highly reflective coins is HDR - high dynamic range.  Basically, you shoot the coin with proper exposure, plus 1 or more stops over exposed and 1 or more stops underexposed.  Photoshop has an automatic HDR feature that then blends all of the photos into one composite image.  There are other programs that will do the same.  The results can be amazing.

[Jay GT4]

Oh i wasn't suggesting you coat those with Krazy glue!  I was just showing what I did on this all but lost cause.  I think a wax wouldn't hurt but if you're just after a better photo Ctgcoin hit the nail on the head. The new Sony cameras do this automatically taking multiple pictures at the same time at different exposures and merging them into one picture.

[Andrew McCabe]

Oh i wasn't suggesting you coat those with Krazy glue!  I was just showing what I did on this all but lost cause.  I think a wax wouldn't hurt but if you're just after a better photo Ctgcoin hit the nail on the head. The new Sony cameras do this automatically taking multiple pictures at the same time at different exposures and merging them into one picture.

Thanks - I have a new Sony camera - specifically a NEX-3 ("large format" type). I don't recall seeing this feature in the menu however. Maybe you could jog my memory where to look, if indeed it is available on the NEX-3/5. I currently use Photofiltre, not Photoshop, but could look to see if there are other utilities that would perform HDR.

http://en.wikipedia.org/wiki/High_dynamic_range_imaging

There seems to a freebie programme, Photomatix, that does the same thing, albeit the free version adds a watermark:

http://www.hdrsoft.com/

[ctgcoins]

Andrew,
Your camera has a DRO (Dynamic Range Optimizer) and Auto HDR feature under the Brightness/Color menu.  In Auto HDR it will shoot only 3 images, but you can select the exposure interval from 1.0 to 6.0 with the left-right buttons.  It cannot be used for RAW images.
Brent