SGL Sigracet 38BC is a thick carbon fiber paper used as a gas diffusion layer (GDL). The substrate is made water-repellent with 5% PTFE and carries a microporous layer (MPL) on one side. A GDL spreads gas to the catalyst layer, conducts electrons and helps remove water. It is supplied as a 100 × 100 mm sheet.

38BC is the thickest and heaviest SGL paper in this group (325 ± 25 µm, 125 g/m²); its porosity is about 80% and it compresses only about 14% at 1 MPa. 22BB is thinner with lower resistance, while 39BB is similar in thickness but lighter and more compressible. It suits cases needing a thick GDL that keeps its thickness well in compressed cells. Catalyst ink is normally coated on the MPL side; do not mix up the two faces.

Key Features

Water-repellent carbon fiber paper treated with 5% PTFE
Microporous layer (MPL) on one side
Thickness 325 ± 25 µm, areal weight 125 ± 10 g/m² (manufacturer data)
Porosity about 80%; low compression (about 14% at 1 MPa)
Through-plane resistance < 11 mΩ·cm² (manufacturer data)
100 × 100 mm sheet
Cutting can release fine carbon fibers and dust; work in a well-ventilated area

Technical Specifications

Material	Non-woven carbon fiber paper (GDL)
Thickness	325 ± 25 µm
Areal weight	125 ± 10 g/m²
Porosity	About 80%
PTFE treatment	5% (substrate)
Microporous layer (MPL)	Yes, on one side
Through-plane resistance	< 11 mΩ·cm²
Air permeability	0.2–0.4 cm³/(cm²·s)
Compressibility	About 14% (1 MPa)
Size	100 × 100 mm