The Framers Forum

Can anybody advise what product to use that will stop silver leaf from tarnishing

Thanks
Mark

Old fashion lacquer. It is the nature of silver to tarnish.

As JFeig correctly said, painting on a laquer will stop the silver tarnishing. To avoid the "plastic" look, you could go on GoldleafSupplies and under shellac varnishes, they have a Crystal Clear Shellac Varnish which would be perfect for the job.
Dilute it 50/50 with meths, use a good quality, flat watercolour brush, press out the excess from the brush and paint over the leaf.