The Iron Cast

Murchadh cursed softly under his breath, reaching for his tool bag. "I've got a heavy hacksaw. We can cut the outer canvas sleeve away—"

"No!" Riosbh shouted. "The vibration from a saw will propagate micro-fractures straight through the hardening canvas into the pressurized bladder! If the bladder punctures in this ambient spore density, I'll inhale forty thousand spores on my next breath cycle! My lungs will fill with calcified foam in under ninety seconds!"

"Then give us the solution, Riosbh," Colmhaign said. His gaze was fixed entirely on her eyes behind the quartz glass. "You know the biology. What stops the enzyme?"

Riosbh felt the cold sweat trickling down the bridge of her nose, pooling near the inner rim of her viewport. Her mind raced through the chemical reagents they had packed into the emergency medical kit inside Colmhaign's pack.

They had two bottles of standard disinfectant alcohol, three rolls of oiled linen bandages, a flask of nitric acid for mineral testing, and a single half-liter glass bottle of buffered phenol-acetic neutralizer wash, meant for treating biological chemical burns.

"Acetic acid," Riosbh said, her analytical faculties taking full control over her fear. "The metalloprotease enzyme requires a neutral or slightly alkaline pH to maintain its catalytic conformation. A concentrated acidic wash will denature the enzyme proteins instantly."

"We pour the acetic wash over the sleeve?" Murchadh asked, already unbuckling the side pouch on Colmhaign's pack.

"Not straight," Riosbh warned sharply. "Pure phenol-acetic wash will strip the linseed oil out of the vulcanized canvas in thirty seconds and dissolve the mutton tallow on the inner calfskin bladder. If the bladder dries out, it loses its airtight seal! We have to buffer it!"

"Buffer it with what?" Colmhaign asked.

"The tallow," Riosbh said. "We need a warm emulsion. Three parts neutralizer wash, one part liquefied mutton tallow, and five drops of nitric acid to shock the pH down to two point five. We have to apply it directly to the active crystallization front while mechanically shaving away the petrified outer canvas layer by layer!"

Colmhaign didn't hesitate. "Murchadh. Strike a sulfur flare inside your tool bucket. Melt two tablespoons of the tallow block against the flare casing. Riosbh, keep your arm perfectly rigid against my shoulder. Do not attempt to bend the elbow."

"Understood," Riosbh breathed, her heart hammering a frantic rhythm against her ribs as she leaned her petrifying arm across Colmhaign's shoulder harness.

The wind tore at them on the narrow ledge. Murchadh crouched low on the girder, shielding his galvanized steel bucket with his own wide back. He struck a sulfur friction match against the rim, igniting a bright, hissing flare that cast an eerie crimson glare across the rusted iron beams and the churning amber mist of the canyon below. With steady, grease-blackened fingers, the mechanic held a chunk of white mutton tallow near the spitting flame, letting the melted animal fat run into a small copper measuring cup.

"Tallow is liquid," Murchadh shouted over the gale. "Pouring the neutralizer now!"

He uncorked the dark glass flask of phenol-acetic wash, carefully measuring out three portions into the cup, then took the dropper from the nitric acid kit and counted: "One... two... three... four... five."

The mixture turned a milky, curdled yellow, releasing a sharp, pungent vapor of vinegar and hot fat that stung even through the suit's exhaust ports.

"Ready," Murchadh said, passing the copper cup to Colmhaign.

Colmhaign pulled his heavy skinning knife from its sheath at his thigh. The blade was high-carbon steel, ground to a razor edge.

"Hold your breath for the cut," Colmhaign told Riosbh. "If the canvas splits, I need you ready to hold positive pressure in your mouth."

Riosbh took a deep breath of the stale, leather-scented air in her hood, clamped her teeth together, and nodded.

Colmhaign went to work with terrifying precision.

Balancing on the narrow iron flange with nothing beneath his heels but two hundred meters of howling air, he dipped the flat of his blade into the warm, curdled emulsion and smeared it along the chalk-white boundary line of the calcified sleeve. The moment the acidic paste touched the Vaeluigh growth, a faint, sizzling hiss arose from the fabric. Tiny bubbles of carbon dioxide froth erupted from the canvas weave, and the pungent reek of denatured organic proteins wafted into the draft.

Using the curved belly of the knife, Colmhaign began paring away the outer canvas, peeling off thin, brittle ribbons of petrified duck cloth like dried wood shavings. His hands were steady, entirely unaffected by the buffeting wind or the vibrating steel beneath their feet. Every scrape was measured, removing half a millimeter of hardened material at a time, never letting the blade tip bite deep enough to score the inner bladder.

Beneath the petrified outer shell, the rubberized canvas was soft, dark, and greasy with the protective emulsion.

"The crystallization front is halting," Riosbh called out through her mouthpiece, her eyes tracking the color change across the fibers. "The acid is neutralizing the zinc-enzyme complex! But the lower weave is still saturated with active spores—pour the rest of the wash over the exposed gusset!"

Colmhaign tipped the copper cup, drenching the elbow joint in the milky yellow fluid. The remaining crust dissolved into a sticky, grayish slurry that ran off the sleeve and dripped away into the void below, vanishing into the churning amber clouds of the canyon.

Colmhaign wiped the blade clean on his thigh and reached down to test the fabric.

The canvas flexed under his thumb with a soft, leathery give.

"Bend it," Colmhaign ordered. "Slowly."

Riosbh drew a trembling breath. She engaged her bicep, pulling her forearm upward.

The joint gave way smoothly. There was no cracking sound, no sudden burst of escaping air. The elbow flexed to a full ninety-degree angle, the oiled canvas folding cleanly in the newly softened bellows.

A long, ragged exhalation shuddered through Riosbh's rebreather valve. Her knees felt hollow, ready to buckle, but she forced herself to stand tall against the concrete stanchion, anchoring her boots firmly into the iron grooves.

"Pressure gauge?" Colmhaign asked, his pick already returning to its belt loop.

Riosbh checked her wrist. "Ninety-one kilopascals. We lost one kilopascal during the chemical reaction, but the inner calfskin bladder is intact. The seal is holding."

Murchadh blew out a long breath that fogged his viewport before clearing through the exhaust valve. He capped the dark glass flask and held it up to the pale light of the canyon.

The neutralizer wash was down to less than half a bottle.

"We used nearly two hundred and fifty milliliters of the medical solvent on one sleeve," Murchadh said grimly, shaking the bottle so the amber liquid sloshed against the glass. "If another suit catches the zinc rot, we won't have enough reagent left to treat a single boot."

Colmhaign looked past the concrete pylon, staring out along the narrow, rusting spine of the transit rail where it disappeared into the darkening maw of the Breath-Tide. Four long kilometers of naked iron girders still stretched between them and the distant, unseen airlock of Station Two.

"Then we make sure our seams don't brush the stanchion rust," Colmhaign said, his voice hard and steady against the rising storm. He checked his harness carabiner and stepped back onto the twelve-inch beam. "Tethers tight. We have three hours before the peak tide hits this gorge, and we are still standing on the wrong side of the crossing."

He turned and began walking the narrow iron line, his boots ringing into the abyss. Riosbh gripped the guide cable with her newly freed hand, set her heel spike into the track, and followed him into the dark.