Cleaning & Protecting an Original London Underground Sign

Ever wondered just how dirty a London Underground sign becomes after years of hanging on the side of a tunnel? Well let me tell you. Pretty darn dirty.

This original sign (recently purchased by our client at an auction and destined to be displayed outdoors in his garden) arrived looking fairly clean on its front side; but on the reverse– as you can see – there was extremely thick layer of original London Underground grime. (There is grime, and then there is proper Dickensian grime, and this – I can assure you – was proper grime.)

Unsurprisingly therefore, our first task in preparing this sign was to clean it thoroughly; and as the sign was enamel, this task was pretty straightforward i.e. mild detergent, warm water and a soft cloth. It took a while – and considerable elbow grease - but it came up a treat!

More challenging however was how to protect the sign while it is being displayed outside. The most pressing concern is moisture getting through cracks in the enamel and causing rust. 

Our client was aware that displaying the sign outside would lead to a deterioration in its condition over time, however he wished to slow this process as much as possible, and as such all the nicks and cracks in the enamel needed to be sealed.

There were some areas of enamel loss where rusting had already begun, so our first task was to remove any rust already present. 

We then dried each of the exposed areas and cracks using warm air to ensure there was no moisture present at all, before finally applying paraloid b44 (a thermoplastic acrylic resin). 


When paraloid b44 dries it forms an invisible seal over the metal, stopping moisture from reaching it and preventing rust. To ensure proper coverage we applied two layers of resin to each area.


This treatment will protect the sign for the time being, however being exposed to the elements will inevitably hasten it's general deterioration, so the sign will need to be assessed every six-nine months and re-treated as necessary.