The tan stopped where the paperback started

One forearm, drawn diagonally across the chest, wrist low at one corner and shoulder high at the other.

The skin is worked in an even stipple, the same tone from wrist to elbow to shoulder.

A third of the way up from the wrist, one rectangle is left completely untouched — pale, square- edged on all four sides, exactly the size of a closed paperback. The stipple sits noticeably darker right at its border, the way skin does at the edge of a real tan line.

The book isn't drawn anywhere. Only the sun's absence under it is.

Why is the palest part of the arm the part with nothing drawn on it?

Because stipple density stands in for sun exposure, and that rectangle got none.

Everywhere else on the arm earned its shading a dot at a time, the ordinary way skin does outdoors. The rectangle didn't earn any of it — something sat on that patch of skin the whole time the rest of the arm was out, and skin that never sees the sun doesn't shade itself in the meantime.

How does a book leave a mark shaped exactly like itself?

By blocking the sun completely over its own footprint while everything around it keeps changing.

A closed paperback has a fixed width, a fixed length and a flat underside. Laid on a forearm in the sun, it shadows precisely that rectangle and nothing more — no soft edge, no gradient, because the boundary between covered and uncovered skin is as sharp as the book's own edge. Move it an hour later and the rectangle would be smaller or in the wrong place; leave it still, and the shape holds exactly.

Why are the rectangle's edges hard instead of soft?

Because whatever caused it didn't move, and a hand or a sleeve almost always does.

A shirt sleeve rolled up and down through an afternoon leaves a blurred, shifting boundary, not a line. A phone picked up and put down leaves a smear of overlapping shapes. A book set down once and left is the rare object that stays exactly where it landed for long enough that its edge becomes the mark's edge, corner for corner.

Whose arm, whose paperback?

Nobody's in particular. There's no title, no cover art and no publisher's mark anywhere in the print — just a shaded arm and the rectangle a flat object leaves on it.

The general point stands regardless. A tan line is yours; nobody licenses the sun. If a real book's cover mattered to the design — its exact proportions, its own artwork reproduced in the pale patch — that belongs to whoever made it, and that kind of thing is licensable when a real one is the point. Here the point is the shape a paperback makes, not which paperback, so there's nothing to clear.

Style has no owner. A work does.

An anatomical line-plate and a blank rectangle are a way of drawing an ordinary afternoon. A particular jacket design is somebody's work. The invented version reads better on a shirt anyway — a recognisable cover is one a thousand people already carry; this shape belongs to whoever's arm it was on.

Does this work for something other than a paperback?

Yes, wherever a flat object sat still on skin long enough to block the sun and nothing else did.

A phone, held loosely for a long stretch, leaves a rectangle with rounded corners instead of square ones. Sunglasses folded on a wrist leave two thin marks, not one block. What stays true is the mechanism, not the object — something with a fixed, flat footprint, left in place, on skin that otherwise kept changing, in the same way a shelf keeps the shape of a book long after it's been taken down. As a gift it reads as a specific kind of compliment: proof somebody sat still with a book bent into a curve by one hand for long enough that their own skin noticed.

Isn't a tan line just something that fades in a week?

Yes, and that's not a problem the design needs solving — it's most of the reason to have one made.

The mark on skin is gone by the time the next week's sun evens it out. A print doesn't need it to last on the body; it needs it to have happened once, clearly enough to draw. The shirt keeps the shape after the arm's already given it back — the same way a book left beside a bed instead of back on a shelf is proof of use that a tidied room would never show.

Does it print well?

Yes — bone ground, soft sepia stippling, one pale gold for the rectangle, and the palette stays that short on purpose.

The stipple is the risk. Too fine at chest scale and it fills in under the weave, going flat and grey instead of reading as shaded skin; coarser, denser in places and sparser in others, it holds up and still describes a rounded arm rather than a shaded oval. The rectangle itself should stay completely flat, with the darkened border right at its edge doing all the work of the tan line — that hard little ring of contrast is the entire mechanism, and it's the one part of the design that can't go soft.

Bone, sand and pale olive all let the sepia read as skin rather than as ink laid over a print of skin.

How do I get one made?

Describe the mark at JustOG — where on the arm it sat, what shape it left, how sharp the border came out. Pick a direction, drag the crop frame, see it composited on the real garment, and it's made to order and shipped.

Designs other people have published are in the shop.

A week of ordinary sun and the arm won't remember it either.