Traditional jack-o'-lantern carving is an art form governed by extreme constraints. Photograph by Matt Gillis.

By day, Van Cortlandt Manor is a historical estate where interpreters in colonial attire give tours, comb wool, and bake kickshaws (from the French quelque chose) at the hearth. The Hudson River borders the property. There’s a gift shop that’s quiet and renovated, and sells old-fashioned candy sticks. But in the weekend evenings leading up to Halloween each year, the manor becomes the site of the “Great Jack O’ Lantern Blaze.” Visitors follow a path that winds through thousands of illuminated pumpkins arranged thematically—dinosaurs, Celtic knots, sea creatures, ghouls.

From August through October, for several summers, I worked as as jack-o’-lantern carver for the “Blaze.” The workers were a mix of site staff and local artists. One day, we would be assigned to work on the undersea kingdom, which meant carving kelp-shaped gashes on twenty or thirty jack-o’-lanterns. Another day, it would be crunch time on the pirate faces. Whether we were stationed in the boathouse next to the geese, or outside on benches under a tent, we worked among garbage bags full of pumpkin guts, arrays of handsaws, X-Acto blades, and wood- and clay-carving tools, as well as dremels, paper stencils, and drawings for inspiration. A first-aid kit was always on hand. Many of the pumpkins were polyurethane, which allowed them to be stored in cardboard boxes for future “Blazes” to come.

Traditional jack-o’-lantern carving is an art form governed by extreme constraints. A pumpkin’s surface is always curved; a light always glows from its base. The whole gourd customarily needs to stand up on its own, without any sort of armature. No area of the rind can be carved into a little island—otherwise that section falls out. As a result, complex carvings can become topological puzzles.

I think the moment I learned to shade was the moment I truly stopped being an amateur. When shading—carving in relief—you don’t cut all the way through to the pumpkin’s hollowed core but instead scrape layers off the rind until it’s thin enough to glow. The inner rinds of pumpkins have thick, fibrous longitudinal ribs, so an evenly shaded outer surface can still yield uneven illumination unless you make sure to address your pumpkin from within. Another consideration is the angle at which you cut into rind.

This diagram depicts the cross sections of two pumpkin shells; an untrained carver might think both sets of incisions, as shown by the dotted lines, appear to have equal widths, and therefore will look the same when lit. But the two apertures actually let different amounts of light through.

There’s also the classic negative-space conundrum: Do you make the biggest holes in your pumpkin correspond to the brightest areas of the subject you’re rendering, such as the forehead of a face? Or is it the black pupils and dark eyebrows that end up being represented by glowing openings?

Not that such precision mattered. More often than not, we faced bigger problems: pulp rotting, blades snapping, shells collapsing. Even if a jack-o’-lantern had been ruined, it usually went on display. The crowd always seemed pleased, for the most part—after all, what could be more appealing than a sea of glowing objects on a cold October evening? Though the smell of pumpkins has seemed slightly revolting ever since, I have good memories of the job. Some years I even catch a train upstate to visit the festival, partly just to see which of my polyurethane pirate heads have survived.

Dawn Chan is the assistant editor of Artforum.com.