Eliminating color from Serish (Eremurus) Paste for paper conservation and restoration.

• Separating coloring compounds from Serish (Eremurus) sticky polysaccharide is possible based on their solubility differences in water and ethanol/acetone. • Ethanol/Acetone extraction proves effective in increasing pH of Serish adhesive. • Stabilizing enzyme before extracting adhesive is an effective method to prevent creating new chromophores by enzymatic molecules degradation. • Extracted adhesive by ethanol from enzymatic stabilized roots provides appropriate pH, color and tensile properties. • Extracted adhesive by ethanol from enzymatic stabilized roots leads neither to paper acidification nor to damaging polymeric structure of paper after accelerated aging. Serish (Eremurus) paste, made of Eremurus genus roots, is a strongly adherent substance which had traditionally been used for book binding and paper restoration in Iran for centuries. The proper pH of Serish and its quality of being reversible after long times has made it a good choice in restoring paper. However, it leaves yellow-brown stains on paper due to its own color, which had negatively affected conservator's desire to make use of this adhesive. Therefore the present study was intended to investigate the process of eliminating color from Serish, as a way of improving its quality for paper restoration. The study adopted solvent extraction method to eliminate color from Serish adherent polysaccharide. Extracted adhesives were coated on paper. Humid-thermal accelerated aging was carried out to investigate the effects of adhesives on pH, color change, tensile strength and cellulose structure of papers. It was found that stabilizing enzyme, using 70% boiling ethanol before extracting adhesive, is an effective method to inhibit enzyme operation and prevent creating new chromophores through enzymatic molecules degradation. This approach, on one hand, is useful in removing color and on the other hand proves effective in increasing pH of adhesives. Furthermore, it leads neither to paper acidification nor to damaging polymeric structure of paper after accelerated aging. The results confirmed that the adhesive extracted from the enzymatic stabilized roots by ethanol provides appropriate pH and color; it also improves the tensile strength of paper and yields more desirable results for conservation of paper-based documents, compared to the other examined samples. [ABSTRACT FROM AUTHOR]