The bench — clay, sand, and five biopolymers. Pick one, set the dose, and read what it does to the mix. More binder feels like more strength. Hold that thought.
plain earth
Flow — how cleanly it extrudes—
Too stiff and it clogs the nozzle. Too thin and it runs.
Hold — how steep a wall it keeps—
Stacked layers have to carry the next layer without slumping.
Printability — both at once—
Flow and hold only line up in a narrow window.
The exception that breaks your rule
The strongest binder is the wrong answer.
Locust bean gum grips the soil hardest — it builds the strongest cured network of anything on the bench. But grip is viscosity: crank it up and the paste seizes in the nozzle. The thing that binds best extrudes worst.
Sodium alginate barely binds at all. Instead it flips the surface charge on the clay so the particles shove each other apart — the suspension stays stable and slick. At just 0.12% by weight it flows clean, holds a steep lean, and cures about 25% stronger. The winner is the one that doesn’t glue.
Take this to The Plug → and watch your mix actually come out of the nozzle.
The plug — you mixed it on the bench. Now open the nozzle and see what comes out.
Carrying your current mix from the bench. Pull the plug to extrude it.