Humidity spots Besides changes in shape (buckling, dimensional changes, etc.), the effect of humidity on paper supports can lead to the formation of spots. The spots are formed when colored water-soluble ingredients contained in the paper, either by construction or as a result from aging, undergo movement. Humidity can also move superficial deposits and dirt.

Total oxidation During macroscopic assessment of the status of conservation status of an artwork's paper support ""descriptive"" terms are often used. These terms are not directly related to chemical phenomena that have taken place and can be identified by physicochemical methods. So, when the term total oxidation is used in relation to a paper support, it refers to the overall degradation of the paper and discoloration - yellowing throughout the area and a reduction of the structural strength (fragility, brittleness, etc.).

Fungi and microorganisms The result of fungi and bacteria is due to several factors, but the most important is still the level of relative humidity in the storage area or exhibition space. If high relative humidity exists, i.e. greater than 60%, there is a serious risk of different types of fungi developing. These fungi have an enzymatic effect which produces a variety of results, differing in nature and appearance, and affect the paper to different extents. However, in most cases, even when their action is suppressed, the aesthetic degradation of the paper is irreversible.

Rodents
Mice often cause large areas of loss to paper, since they find paper to be a suitable material for their nests. Loss caused by mice is easily recognizable by the lace-like finish their teeth leave behind.

Tears / holes Paper is a material which is very sensitive to mechanical stress. Even the most durable paper can be easily torn or show holes if it undergoes mistreatment.

Destructive procedures Older maintenance procedures and certain adhesives made of inappropriate materials, such as adhesive tapes, have devastating effects on artworks with a paper support. In certain instances, the results of these procedures can cause irreversible damage and permanently alter the aesthetics of the image.

Technique The transition from handmade to industrial paper was accompanied by the introduction of lignin in the basic composition and a general deterioration in quality. In addition, materials used occasionally, e.g.. the rosin used for sizing (sizing changes the absorption and wear characteristics of materials), proved to be errant choices which greatly accelerated the natural aging process of the paper.

Technique In some cases, the technique used in the creation of a painting or drawing introduces certain components which can cause deterioration of a paper support during the natural aging of the work. Iron gall inks are an example of exactly this type of component. They cause a specific reaction as they stabilize which results in the creation of sulfuric acid, which in the long term causes intense wear on certain areas of the paper. The drying oils also have an effect on the structural integrity of paper, especially if no primer/ground layer has been applied between the support and the painted image.