The polished top rail on this sofa is a piece of show-wood, which means it is furniture and upholstery at the same time - and the join between the two is the whole difficulty.
Where a covered frame meets a polished one, the cloth has to stop somewhere, and that stopping point is either neat or it is the first thing you see. The traditional method is a groove: a shallow channel is cut into the timber along the line where the upholstery ends, and the raw edge of the cloth is tucked down into it and held there, so the fabric appears to disappear into the wood.
Our artisans cut that groove before the timber is polished, and polish over and into it, so the finish runs continuously into the channel. If the groove is cut afterwards, its edges are bare timber and they darken over the years into a visible line.
The upholsterer then works to the polished rail without touching it - the cloth is tucked and set with the timber already finished, which takes considerably more care than upholstering first and polishing after, and is the only order of work that leaves both surfaces perfect.