PRZYCZYNY I MECHANIZMY ZMIAN WYGLĄDU UZUPEŁNIEŃ WARSTW MALARSKICH W OBRAZACH SZTALUGOWYCH

The supplementation of gaps in the painted layer, executed professionally and with the assistance of material adapted to this particular purpose, does not always prove to be as stable as might be expected. Changes in appearance, which sometimes occur soon afterwards, or even a mere modification of the conditions of exposition cause conservators much anxiety especially when the supplements were imitative and as a result of the changes ceased to play their intended part and began to draw attention. The effectiveness of counteracting undesired changes in the appearance of the supplements depends on a suitable comprehension of the mechanisms of their origin and on apt diagnosis. The intention of the presented article is to explain the probable reasons for optical changes observed in supplements of gaps in the painted strata of restored easel paintings. Changes in the gloss, covering and assorted colours have been discussed in reference to concrete material heretofore encountered in supplements. The author drew attention to assorted causes which could include metamerism, phenomena associated with drying, the properties of the applied material - binding, pigments and solvents, and sometimes their mutual impact or the optical effects of ageing.