Profil „H“ 2,5 mm

A little H-section 2.5 mm high

A strip of white polystyrene whose cross section consists of two opposing channels joined by a web. Each channel can grip the edge of a thin sheet, so the profile becomes either a freestanding post or an invisible junction of two panels into one surface. The height of the section is 2.5 mm, the strip measures 35 cm and one strip makes up the item.

A light material does what it likes with a shade

The polystyrene of this series throws light back through the coat laid on it. Dark reds and saturated browns therefore pick up a pinkish tone from it and have to be gone over three times before they sit where you want them. A gray or black primer cancels that effect at the first pass and additionally gives the smooth extruded surface a tooth for the pigment to grip. Without an undercoat the paint holds only mechanically and will lift the first time it is squeezed between fingers.

A coat of primer also works as an inspection

An even matte coat brings to light everything that blends in on a glossy white strip: file marks, squeezed-out cement and grease from a hand. That is exactly why the profile is primed before it disappears inside an assembly, where nobody can reach it any more.

• Wash it in lukewarm soapy water and let it dry thoroughly.
• Lay the primer down in two light passes, not in one wet coat.
• Sand any flaws found with a fine sponge and respray the spot.
• Only then reach for the shade that is meant to show.

It is divided with a sharp knife led along a ruler and joined with liquid solvent cement for styrene.