Cellulose insulation is made from paper products, primarily recycled newsprint. The paper is shredded and milled to produce a fluffy low-density material. Large amounts of chemicals, primarily boric acid, are added to provide flame resistance. The great advantages of cellulose are its relative low cost, ease of installation and high R per inch, roughly 25 percent higher than glass fiber. Its disadvantages are it can absorb moisture which may alter its physical and chemical properties and it may settle if not applied at the correct density.