Investigation of the stabilization of verdigris-containing rag paper by wet chemical treatments

Heritage Science

Table 1 Chemicals and application methods tested

	Chemical	Details	Application methods
Blank carrier	Water	Deionized	Spraying on a suction table
Blank carrier	Ethanol	96%	Spraying on a suction table
Deacidification	Calcium hydrogen carbonate in water and ethanol mixture (2:1)	<0.012 M in water diluted with ethanol	Spraying on a suction table, brushing on the verso
	Calcium hydroxide in water and ethanol mixture (2:1)	Saturated solution diluted to pH 9.3 with water and then mixed with ethanol	Spraying on a suction table
	Magnesium hydrogen carbonate in water and ethanol mixture (2:1)	<0.012 M in water diluted with ethanol	Spraying on a suction table, brushing on the verso
	Magnesium propylate^* in 1-propanol	5% v/v	Spraying on a suction table, the same as without suction
Antioxidant	Tetrabutylammonium bromide (TBAB) in ethanol	0.03 M (~1% w/v)	Spraying on a suction table, brushing on the verso
Antioxidant	Ethyl p-hydroxybenzoate (PHB) in ethanol	0.2%, 1% w/v	Spraying on a suction table, brushing on the verso
Complexation	1H-benzotriazole (BTA) in ethanol	5%, 0.5%, 3% w/v	Spraying on a suction table, brushing on the verso
	Two step-calcium phytate/calcium hydrogen carbonate treatment^**	1.75 mM Ca phytate in water followed by 0.012 M CaCO₃ in water	Spraying on a suction table
	Modified calcium phytate^*** in a mixture of water and ethanol (2:1) (M-Ca phytate)	1.75 mM Ca phytate in water and ethanol (2:1)	Spraying on a suction table, brushing on the verso

^*The reagent was provided by PAL Preservation Academy GmbH Leipzig. 5% (v/v) of the reagent in 1-propanol can deposit around 0.5% w/w of MgCO₃ in Whatman no. 1 paper by spraying.
^**References: [20, 21].
^***It was modified by adding a non-ionic surfactant mixture to increase solubility (stable suspension) of calcium phytate in water and ethanol mixture. Details will be presented elsewhere.