Mr Wright later uploaded a picture to Twitter which showed five or six words on the bottom-right corner of the painting with black streaks of paint running down from the daubed writing.

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The painting depicts a black American businessman getting his shoes shined.

FORBES: Magazine Article

The origins of Ati-Atihan date back to the 13th Century, when a group of lighter skinned Malay immigrants from Borneo chose to show their respect for the local Ati people by painting their faces black and singing and dancing in thanks for the land and food that was offered to them.

BBC: Ati-Atihan festivites on Philippine shores

Residents have described painting the lines in the first place as a "little bizarre" but painting over them in black paint as "even more bizarre".

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If Boston collector Scott Black likes an Impressionist or modern painting, he checks the year it was made, because huge fluctuations in value can hinge on whether the piece dates to an artist's best-loved period or amounts to a fluky offshoot.

WSJ: Following the Smart Art Money

The 1.85m-high Soviet-style, red black and yellow acrylic painting has been sold.

BBC: Jacob Zuma painting: ANC to sue South Africa's Brett Murray

In 2011, for his "Beautiful Sunflower Panerai Painting, " he used hundreds of black Panerai watch faces, without their hands, to create a spin painting for the "O'Clock" exhibition at the Triennale Design Museum in Milan.

WSJ: Where True Value Lies