Poly cement doesn't stick plastic together — it welds it. The solvent melts the two mating faces, and as it flashes off, the parts fuse into a single piece of polystyrene: a joint that's part of the model, not a layer between parts, and stronger than the plastic around it. Humbrol's Precision Poly delivers that chemistry through a very fine metal tube, placing tiny, controlled amounts exactly on the joint line — no blobs, no squeeze-out, no melted fingerprints in the surface detail.

Precision Is the Point

The low-viscosity formula and needle-fine applicator exist for the moments standard tube cement ruins: fine parts, visible joint lines, cockpit details, railings and undercarriage legs, anywhere excess would show. Touch the tube to the seam, let capillary action draw the cement along the joint, press the parts together — done. One tip worth its weight from long experience: cap the needle between applications, even for a minute — the tube is fine enough that dried cement will block it for good, and a capped bottle lasts the full 20ml.

Polystyrene and ABS Only

This is a solvent weld, so it only works on plastics it can melt: the polystyrene and ABS that model kits are moulded from. It does nothing useful on resin, photo-etched metal or diecast — those need CA or epoxy — and it should never touch the visible face of clear parts, which it fogs and melts like any styrene. Right chemistry, right materials, perfect joints.

Forgiving While It Works

Joints are surface dry in 10–20 minutes and fully cured in an hour (faster in warm, dry conditions) — and until full cure, a misaligned part can be re-dissolved and repositioned with a little more cement or Liquid Poly. Permanent once dry, which is exactly what you want from it.