An 130-year-old painting by French impressionist Claude Monet was seemingly irreparably damaged after an incensed man punched it in 2012 while was on display in Dublin's National Gallery of Ireland.

The man was sentenced to 5 years in prison last year, but "Argenteuil Basin with a Single Sailboat," a panting worth an estimated $12 million, now had a hole thought it with cracked paint and a broken canvas.

Now after an 18-month restoration process, conservators at the gallery completed the seemingly impossible job of repairing and restoring the painting.

Here's how they did it, according to the process the gallery posted on its website:

The painting was carefully removed from its frame before the restoration could begin. National Gallery of Ireland The first step, of course, was to remove the damaged painting from public display. It was then taken out of its frame and restorationists noted any changes in condition from when it was previously inspected.

The underside was where the real repair work began. A protective film was applied to the painting while it was flipped.

A protective coating had to be applied to the painting before the canvas could be repaired from the other side. National Gallery of Ireland

The damaged canvas had to be flattened and aligned before it could be rejoined. A small amount of moisture was applied and, thread by thread, the canvas was rejoined using a microscope and tiny tools.

A specially made adhesive helped secure the canvas threads.

An adhesive was used to glue the broken canvas threads one false move and the canvas would have been lost forever. National Gallery of Ireland When the painting was punched, the paint cracked, split and chipped off. Larger paint fragments were able to be reattached to the canvas, but the smaller pieces (barely bigger than specs of dust) were not.

Instead, conservators added a chalk glue solution called gesso to fill in the areas of paint loss. It was pigmented identically to the painting so as to blend right in. Watercolor was then added on top of that to finish off the restoration.

Cracked paint was reattached to the repaired canvas. National Gallery of Ireland

A microscope was used to repaint the damaged canvas. National Gallery of Ireland The final result is a painting that looks like it's old self again.

The repaired painting. Can you tell the difference? National Gallery of Ireland All the materials used in the restoration are reversible and easily removable without destroying the original paint, should the need to do so ever arise. Additionally, the watercolor used shows up darker in ultraviolet light so it's easily identifiable.

Looks like a job well done.