SINGAPORE - Dust and who knows what else has been accumulating for over 21 years but that didn't deter Ms Birte Koehler and her brush and handheld vacuum cleaner.
Ms Koehler, the senior object conservator at the Heritage Conservation Centre (HCC), was among three experts tasked with cleaning one of the two flight information display flip boards that used to tower over departing passengers at Changi Airport's Terminal 2 (T2).
The boards have had their day. The transition from analogue to electronic was inevitable, given the challenges of maintenance and increasing difficulties in procuring replacement parts.
Even the company that manufactured T2's boards in 1999 has ceased production of their components.
Electronic displays can show far more flight detail than the archaic analogue boards in T2 could, and they take less time and manpower to maintain.
Each analogue board comprises more than 2,000 capsules of individual letters and numbers, towering at 4.5m in height and 15m long.
Their usual role of presenting flight details deviated in 2016 when the flip boards celebrated Joseph Schooling's Olympic victory by displaying his winning time.
If it is of any comfort to travellers, Mr Ang Siew Min, senior vice-president of development operations at Changi Airport Group, said there are plans to "re-use the last remaining flip board, to be retired in about two years' time, in a different part of the airport as a display piece to be enjoyed by all who visit".
About 20 people were involved in de-installing the flip board over the past two weeks.
The pieces are undergoing cleaning and packaging at the Global Specialised Services Warehouse. They will then be transferred to the HCC, which is a part of the National Heritage Board, to join Singapore's National Collection.
Mr Alvin Tan, the National Heritage Board's deputy chief executive for policy and community, said: "We believe that (the board) is an important piece of airport infrastructure and a formative feature of the air travel experience.
"Many Singaporeans will remember standing underneath the boards, listening to the clickety-clack sounds of the split flaps and waiting for their flight information to be displayed."
On the challenges faced by the conservators, Mr Tan said the process is quite time-consuming, as there are more than 2,000 components to be cleaned.
"We also have to take a lot of care, because some of the components are quite fragile and replacement parts might not be easily found."
A single module takes two to five minutes to be thoroughly cleaned.
Ms Koehler said the repetitive process of cleaning the modules in a similar fashion over an extended period allows her to get into a quiet rhythm: "It becomes a meditative process; you tune in with the pieces that you are working on."
The entire process is estimated to take six months.