A counterweight is a stand-in for a load you can't see

A tall vertical stack of flat weight bricks, side on, loaded onto a frame. A rope runs up from the top of it, over a block, and off the edge of the shirt. A small plate on the frame reads 340 KG.

Nothing above that number is in the picture, and that's the whole idea.

What is a counterweight arbor actually holding up?

Nothing directly — it's holding up the other end of a rope, and something else entirely is on that rope.

A flying bar hangs above the stage, out of sight of the arbor, carrying whatever's rigged to it — a cloth, a length of truss, six lanterns. The arbor sits at floor level on the opposite end of the same rope system, and weight gets loaded onto it until it roughly balances what's hanging above. The arbor isn't the load. It's a physical answer to a question about a load in a different part of the building.

Why load it with a stack of bricks instead of one solid weight?

Because the load overhead changes show to show, and a stack can change with it.

Each brick is a known, fixed mass, working the same way as a stack of individually cast weights sitting on their own — same units, different job, because these ones spend their whole working life offsetting somebody else's load rather than their own. Add or remove bricks and the total on the arbor moves in known steps, matching whatever's currently flying. A single cast weight sized for one particular bar would need replacing every time the load changed.

What does the number on the plate actually describe?

Not the plate. Not even the arbor. It describes whatever's hanging on the other end of the rope, restated at floor height.

340 KG on this plate is a claim about an object thirty feet up that nobody loading the arbor can currently see or touch. Get the figure wrong in one direction and the bar won't fly at all — the arbor's too heavy to lift it. Get it wrong the other way and the bar can run away with the arbor underneath it, which is the failure this whole system exists to prevent.

Is a working load figure like this something anyone's allowed to put on a shirt?

A number on its own belongs to nobody — it's an invented figure here, not lifted off real equipment.

A working load limit or a rating like this one is a manufacturer's certified statement about one specific piece of real equipment, checked and stamped against that piece and no other. Printing one as decoration is fine. Reading a real rating off a shirt and trusting it for anything is not what this object is for, and this design keeps the two apart on purpose by using a figure nobody could mistake for equipment they actually own.

Does the same logic apply anywhere outside a fly system?

Anywhere a counterweight is standing in for a load somewhere else, yes — a lift, a crane, or a shackle taking that same load at the exact point where it attaches.

A crane's counterweight is the same idea scaled up: mass at one end balancing a load nobody at the controls can directly feel. What changes at theatre scale is how often it happens — an arbor gets reloaded for scene changes within a single show, sometimes several times a night, by somebody doing sums under time pressure that a crane operator does once per lift.

Isn't a system this consequential a strange thing to reduce to a shirt?

Only if a stamped weight and a checked figure are less honest than a picture of a finished show, which isn't obviously true.

The people who load an arbor for a living have spent years getting a physical feeling for what a given mass overhead should require underneath it, and a shirt that shows the actual mechanism — bricks, rope, plate, number — reads as accurate to that work in a way a photo of the show itself never would. It's a badge for the sums, not for the spectacle.

Does it print well?

Yes — the stack is a repeated flat shape, and repetition is easy to hold onto in print.

Cream for the bricks and the frame, red for the plate and the number, on a slate or charcoal ground. Keep each brick's edge hard and distinct rather than letting the stack blur into one tall rectangle — the individual units are the part of the drawing that explains how the load actually gets built up.

How do I get one made?

Describe your own rig at JustOG — how tall the stack, what the plate should read, which colour carries the number. 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.

340 KG on a plate at floor level, describing something thirty feet up that nobody loading it can see.