Oak gall or gallnut is used to mordant cellulose fibers and fabrics before an alum mordant is used. Alum does not combine well with cellulose fibers as it does with protein fibers.
Oak galls is from the oak tree and are one of the earliest and tannin rich sources for natural tannin. Galls are produced by insects that deposit their eggs in small punctures on young branches and leaves. The tree excretes a tannin-rich substance that hardens and forms a gallnut.
Oak galls can be collected and ground for use as a tannin mordant.
Use at 10-12% WOF or 6-8% WOF for gallnut extract.