Cellugel uses cellulose ethers (specifically hydroxypropylcellulose) and isopropanol to treat red rot by penetrating the surface of leather. It consolidates the leather substrate, depositing a thin film which provides resistance to atmospheric conditions but does not darken or discolor leather surfaces. It will not stain other materials with which it comes in contact. Cellugel dries quickly and the book may soon be handled safely. A second coat may prove necessary for extremely thick or badly deteriorated volumes. It is an excellent choice for consolidating powdery leather surfaces prior to conservation treatments. If the top is kept closed, the product should not evaporate, however, a little 100% isopropanol may be used for thinning. Water should never be used, as it will cause staining and blackening of leather surfaces. Expect a 16-oz jar to treat about 60 books measuring approximately 6 x 9 in. No special ventilation is required.