I recently treated a tremendous set of 2 union jack Tram lights- these were made to be mounted to the sides of the No.17 double decker tram during Peace celebrations in 1919 and for the Royal Visit in 1920.
They were each fabricated in large rectangular wooden board formats. Their front surface used wooden frame profiles designed and nailed to the base in a Union Jack painted lay-out using conforming red, white and blue paint . Corresponding red, white and blue bayonet mounted lightbulbs were inserted through holes in the base boards and their connected wire circuitry protruded through the rear to allow for what would have been a spectacular illuminated effect from each tram side.
All the paint previously applied and adhered to each lightbulb surface was seriously fragile, embrittled and peeling away from the underlying glass. Both the painted surface the wood and glass bulbs was significantly dirty with ingrained and loose dirt.
This paint surface needed to be cleaned and stabilised concurrently amounting to an arduous and difficult treatment consisting of research into types of appropriate consolidants that resulted in no or little change to the paint surface in terms of colour , texture or gloss.
Easier said than done and all in a tight timeline too!