https://en.wikipedia.org/wiki/Offset_printing

Fountain solution is the water-based (or "aqueous") component in the lithographic process that moistens the non image area of the plate in order to keep ink from depositing (and thus printing). Historically, fountain solutions were acid-based and made with gum arabic, chromates or phosphates, and magnesium nitrate. Alcohol is added to the water to lower the surface tension and help cool the press a bit so the ink stays stable so it can set and dry fast. While the acid fountain solution has improved in the last several decades, neutral and alkaline fountain solutions have also been developed. Both of these chemistries rely heavily on surfactants–emulsifiers and phosphates and/or silicates to provide adequate cleaning and desensitizing, respectively. Since about 2000, alkaline-based fountain solutions have become less common due to the inherent health hazards of high pH and the objectionable odor of the necessary microbiological additives.

https://pt.wikipedia.org/wiki/Impressão_offset

- Pelo sistema de molha: 1. Sistema com molha convencional: usa uma solução de molha composta em maior quantidade de água, e uma parte de solução de molha.

https://www.printing.org/intertech-entries/fountain-solution...