Tucked into a quiet corner of West Town, the Conservation Center may be the art world’s best-kept secret. Run by Heather Becker, a painter who trained at the Art Institute of Chicago, the 31-year-old business is the largest private art lab in the country. Fifteen conservators care for rotating groups of works, sent from museums and private collectors around the globe, with damage that would make any curator cringe. Processes demand profound patience and attention to detail. Here are examples of five.

Inspecting for damage

Conservator Amber Schabdach discovered the outlines of a face after putting this 1970 Ed Paschke painting under an ultraviolet light to look for evidence of old repairs. The visage was likely part of an early iteration of the painting.

Removing old varnish

Over time, the varnish on paintings yellows and needs to be stripped. Here, Amber Schabdach uses an organic solvent for the task on a Luther G. Narcomey painting.

Repairing ancient books

A handwritten codex, over 1,000 years old, was found in an attic in Constantinople and will take nearly 400 hours to treat. Restoring the book’s pages, nibbled by mice and crinkled by water stains, involves humidifying them and then flattening them under 120-pound weights. “It’s definitely one of the oldest things I’ve worked on,” says senior paper conservator Brian Kapernekas.

Applying new shellac

After 150 hours spent repairing this 1870s Dutch bureau that suffered considerable damage (swelling wood, crumbled veneers, fading), a conservator adds the finishing touch: dabbing the carved tulipwood and boxwood in careful figure eights with a polishing rubber.

Cleaning fragile textiles

This 1840 silk English wedding dress, a handmade and impeccably preserved family heirloom, gets lightly treated with a dry sponge and vacuum.