Detecting Inpainting in Artwork

If you’ve spent time around artists, museums, or artwork in general, you have probably heard the term "inpainting." Simply put, inpainting is a process that reconstructs deteriorated portions of a painting or image.

The term can be also be used in reference to the replacement of corrupted or lost parts of a digital image, and is also known as "image interpolation" or "video interpolation."

In the world of fine art, a painting may have experienced varying degrees of deterioration, loss or damage that an owner or institution wishes to restore. An art conservator is called in. The best conservators are able to match pigment and texture so well that an expert eye is needed to spot it – or at least eyes armed with the right technology.

Naturally there is an army of things to consider before executing any inpainting: light and color phenomena, pigments and their properties, preparation and fills, wet and dry inpainting, media and toning systems – generally synthetic resins, watercolor, gouache, gums, pencils, pastels, dyes, etc. And there are inpainting modifiers such as bulking, glossing, matting and polishing agents; medium/pigment/diluent adjustments for unique structures, the application instrument, and of course any overarching philosophical or ethical considerations.

So, let’s assume we suspect a work of having inpainting, but the conservator was highly skilled. One of the easiest ways to discover it without the benefit of an art museum’s conservation laboratory is by examining the work under ultraviolet light, a common UV-A “black light.”

I recently examined a painting by Anton Lhota (Austrian, 1812-1905), an oil on linen biblical scene of a horrified Judas returning the thirty pieces of silver reward money as he sees Christ carrying the cross through a window. The painting was professionally restored in 1985, and included inpainting with Liquitex acrylic above Judas' head, and an isolating varnish.

Unlike major museum quality restorations, the inpainting here is visible to the naked eye - if you know what you're looking for, but a simple black light in a dark room readily reveals the restoration.