Black Threads in Spalted Elm: Fungal Mycelia, Not a Hazard

What Those Jet-Black Strands Are

The thin, thread-like black filaments growing from your spalted elm blanks are fungal mycelia (often called mycorrhizae in this context). They appear when the wood’s moisture content is high enough to support active fungal growth.

No Extra Risk Once Dry

As the wood dries, the filaments stop growing and become inert. Simply let the blanks air-dry thoroughly, then turn them as you would any other spalted wood. The unique patterns are prized by woodworkers and pose no health or safety concern.