Coin problem

[ggx51]

Hi, can you tell me what the issue is on the coin between the B & the R, can it be removed without damaging it?

[Paddy]

Welcome to the forum @ggx51!

It is difficult to see exactly what you have there - the picture appears black and white - is there any colour? That might indicate verdigris or some attached organic material. I take the coin is a Victoria Sixpence?

The usual approach is to try things in increasing strength. Start with warm water and soap. If the material is organic a soak in Acetone would probably shift it. All these arevery unlikely to damage the underlying coin. Obviously don't scrub with anything abrasive!

Thereafter you are into chemicals, which is more risky. The recent trials of Sodium Sesquicarbonate solutions have been successful on Bronze and Copper coins, but I have no idea whether it would work on silver. It is very gentle and slow, so should do little other damage. (Buy it as Borax substitute on Amazon.)

Mild Ammonia solution is the next level up, but that will remove all the patina. So if you are unwilling to do that, best left as it is. Verdicare is a commercial product that might help, but it is difficult to get in the UK.

I hope that helps.