Waterproofing a leaded light window

[RichD1]

I have a leaded light window on our landing and recently water has started to weep through the lead strips. I can’t tell exactly where it is penetrating so was wondering as I have a can of Thompson’s water seal in the garage whether I could paint this around the joints on the outside using a very small artists brush and wiping off any excess.

Would this work?

Richard

 

[footprints]

I think originally the lead was polished with some sort of wax maybe this sort of thing.
https://www.creativeglassguild.co.uk/prod/black-graphite-polish-for-blacking-lead
It might also do the job of sealing tiny gaps in the lead.
Try searching youtube for making or repairing leaded glass and see what they do.