Funding came from The European Fine Art Foundation (TEFAF) Museum Restoration Fund as well as help from the Friends of the Museum and The Finnis Scott Foundation.
The Manet (1832-83) picture was bought by the museum in 2019 via the government acceptance in lieu scheme.
It had previously been in the same private family collection for more than 90 years. The picture is of Jules Dejouy (1815-94) who was Manet’s older cousin and an important figure in the artist's life. He was a successful lawyer, appointed to the Imperial Court in France in 1849.
After the death of the artist’s father in 1862, Dejouy was appointed as chief counsellor and guide to Manet and his brothers.
Dejouy was also appointed by Manet as his executor and was part of the committee that organized the 1884 exhibition following Manet’s death. This portrait was included in that exhibition.
Adam Webster, chief conservator or art, natural sciences and presentive conservations at National Museum Wales, said: "The painting is currently under a veil of surface dirt and discoloured varnish. Removing these will likely recover the subtlety in the painting and also re-saturate the image to recover a sense of depth.”
The TEFAF fund was established in 2012 and each year a maximum of €50,000 is allocated to projects – usually two a year. Since the founding of the fund, almost 20 museum projects have been supported.
The second winner of this year's fund is The Beirut Glass Project, a collaboration between the British Museum and the American University of Beirut.