Phenolic is a thermosetting resin (phenol formaldehyde) that sets hard and heat-stable once cured. In laminate form, the form Tufnol makes, layers of paper or woven cotton are impregnated with phenolic resin and pressed under heat to create a strong, rigid material with good electrical insulation and excellent machinability. It is the basis of Tufnol’s paper (SRBP) and cotton fabric (SRBF) grades. See the phenolic paper grades on the paper laminates page.