Drain Descaling

The scale signature:

• Chronic slowness, everywhere the iron runs. Not one clogged fixture but a general sluggishness in the cast-iron sections: capacity loss, not blockage.
• Clogs without a culprit. Repeated stoppages with nothing to show (no wipes, no grease event), because the rough, narrowed walls themselves are catching ordinary flow.
• Relief that never lasts. Cabling that buys weeks instead of years: the tunnel-through-scale pattern, and the strongest clue that the problem is the walls.
• The camera's verdict. On inspection: ragged buildup, reduced bore, rough surfaces the lens can barely pass. Scale visible as geology, which is exactly what it is.

This page covers descaling as a method: when scale is genuinely the diagnosis, how chain-and-flex tooling does the work, and the camera proof on both ends of it. Its honest boundary is structural: descaling restores dimension to sound pipe; cracked, collapsed or corroded-through iron is rehabilitation territory, and the inspection that qualifies a pipe for descaling is the same one that catches the disqualifiers.

How descaling runs:

• Camera first, always. Descaling is prescribed from footage, not symptoms. The inspection confirms scale, measures the pipe's remaining soundness, and catches the cracks and collapses that disqualify mechanical cleaning.
• The machining pass. Chain knockers and flexible-shaft tooling sized to the pipe spin against the walls, breaking scale off in fragments: aggressive to buildup, calibrated to the iron beneath, worked in passes along the run.
• Flush and capture. Broken scale gets flushed and carried out of the line. Left in place it just becomes the next blockage somewhere downstream.
• Camera again. The after-footage is the deliverable: restored diameter, walls visible, and an honest record of the pipe's true condition now that the scale no longer hides it, sometimes revealing repair needs the buildup concealed.
• The verdict either way. Sound descaled iron returns to service with years ahead; iron that scale was holding together routes to lining or replacement with footage in hand. Both outcomes beat not knowing.