Partially Fire Resistant Insulation Material Comprising Unrefined Virgin Pulp Fibers and Wood Ash Fire Retardant Component

A process comprising the following steps:

• a. providing a fibrous web providing an R-value (as measured by the ASTM C518 test) of at least about 3 and comprising:
• from about 5 to about 85% unrefined virgin softwood pulp fibers by weight of the fibrous web;
• and
• from about 15 to about 95% unrefined virgin hardwood pulp fibers by weight of the fibrous web;
• and
• b. treating the fibrous web with a wood ash fire composition comprising a wood ash fire retardant component such that the wood ash fire retardant component is present in and/or on the fibrous web in an amount of at least about 1.5%, by weight of the fibrous web and sufficient to provide a cellulosic fiber thermal insulation material which is at least partially fire resistant (as measured by the ASTM E970-08A test).