Uncoated paper

Valuable results with Tof-SIMS imaging have been obtained e.g., with paper samples. The distribution of papermaking chemicals on the surface of coated and uncoated papers is very important for its further treatment, such as printing. Figure 16 [70] is an example of use of the technique for chemical microscopy analysis of paper surfaces. 

Duplicator and Business Form Inks. Duplicator sheet-fed machines require very press-stable yet quicksetting inks. They must also possess good lithographic properties of wide tolerance for fountain solution and provide good printing properties on a wide variety of uncoated papers. 

Currently used water soluble yellow ink-jet dyes include monoazo dyes C.I. Acid Yellow 17, 18965 [6359-98-4] and C.I. Acid Yellow 23, 19140, [1934-21-0] which exhibit symmetrical narrow absorption bands, as well as the disazo dyes C.I. Direct Yellow86, 29325 [50925-42-3] and C.I. Direct Yellow 132 [61968-26-1]. Recently developed, improved yellow dyes include disazo dye 5 of the type C.I. Direct Yellow 86, 29325, but modified by introducing carboxyl groups. Similar to C.I. Direct Black 195, this dye shows a high waterfastness on uncoated paper due to differential, pH-dependant solubility [3,12],... 

Some of Fischer and Duncans observations supporting the above ratings (based on the one type of coated- and the one type of uncoated-paper books) are ... 

A) Drying techniques that work well on uncoated paper do not necessarily work well with coated stock (4). 

F) The one type of coated paper used in this study absorbs 80% more water than the one type of uncoated paper used (2). 

G) If proper environmental conditions are selected, the one type of uncoated-paper book showed that almost all absorbed water will be released by draining in 120 hr (4). 

J) Absorption of water by coated paper can be more rapid than that for uncoated paper. 

Table I shows the overall variation in the weights when the simulated-flood procedure was applied to similar pairs of identical books over an 8-mo period. The simulated flood was applied to these books as if they were loosely packed on the shelf—i.e., stored with minimum pressure applied to them. The relationship of each book s dry weight with the temperature and relative humidity of the room appears to have been comparable. The variability of the wetting action of both types of books is also similar however, the variances (the standard deviation squared) associated with the weights of the drained books are significantly different (statistical significance reported at the 95% confidence level unless otherwise noted) by use of an F-test (3). Since the handling of book pairs—i.e., one uncoated- and one coated-paper book—was the same in preparing samples for subsequent restoration studies, it might be concluded that drainage water from the books containing uncoated paper could be different from books with coated paper.

The loosely packed coated- and uncoated-paper books absorbed more water than the tightly packed books—approximately five times as much for the coated- and twice as much for the uncoated-paper books. In both series of experiments more than 93% of the water absorbed in the loosely packed, uncoated-paper books evaporated during a 120-hr drainage period. These experimental results could explain why several of the actual frozen, flood-damaged, uncoated-paper books, after thawing, contained only small amounts of water. They were perhaps the last uncoated-paper books to be packed and frozen after the flood waters receded. 

Differences in water loss by those uncoated- and coated-paper texts previously flooded in the tightly packed book position may exist. The amount of the loss, 1 g and 3 g, respectively, is very small. The loss of water from the coated-paper text of the loosely packed books seems to be greater than for the uncoated-paper, loosely packed books. Drainage of water from the loosely packed coated-paper text appears to be greater than that noted for coated-paper text in the tightly packed book position. 

To establish the final visual rating for each book, the average was determined from the individual ratings and entered into Table VI. This table lists the individual visual and property rating results for both the uncoated- and coated-paper books. A maximum visual rating of 16 for a book was not achieved. The highest value acquired for a coated-paper book was 10.0. A higher value of 13.0 was obtained for an uncoated-paper book. It is important to remember that this visual evaluation included... 

The results of rating physical-chemical properties for all the uncoated and coated books are given in the fourth column in Table VI. A maximum value of 16 was obtained for the uncoated-paper book a value of 14 was obtained for the coated-paper book. The zero rating values assigned to the physical property measurements for the coated-paper books clearly identified the limitations of these processes for drying this type of coated paper. 

After books are subjected to a flood, the loosely packed, uncoated-paper books can release almost all the water absorbed during a 120 hr drainage period if the environmental conditions are equivalent to, or more favorable than, those prevalent during this drainage study. Such results can be expected only if mold or biological growth does not take place in the books. 

Freeze-thaw vacuum, inter leave-air, and solvent extraction processes offer the greatest potential in drying these types of coated- and uncoated-paper books after they have been wetted and frozen. The drained-air, vacuum-air cycle, vacuum, microwave, and dielectric drying processes work well on uncoated paper, but they fail to dry books containing this type of coated paper. Small and large units for freeze-thaw, vacuum drying have been used successfully to remove water from these frozen coated and uncoated books. 

The text of the frozen uncoated-paper research book was dried in the next experimental run with this oven. Eight 45-sec bursts of energy were required to remove the water from this lightly wetted 244.5-g text. The amount of water absorbed by this text during the simulated flood was small since it was in the tightly packed position (1). Its dry weight... 

Special Research Books. The sandwich technique, placing the wetted book between two inert plastic trays, was used to dry the flooded, drained, and frozen coated- and uncoated-paper research books (1) in an improved 27-MHz heater. The covers of these books were not removed in applying this drying procedure. 

One frozen uncoated-paper research book weighing 480.5 g was dried by applying 20 30-sec bursts. The final weight of the dried book was 287.5 g. The sandwich technique used for this book, cover intact, gave excellent results. 

A replica of the previous flooded, drained, and frozen uncoated-paper research book was dried by again applying the sandwich technique in another 27-MHz heater. The frozen weight of the book was 449.0 g the dry weight was 290.0 g. Only 14 30-sec bursts, contrasted to the earlier 27-MHz heaters 20 bursts, were required to thaw and to dry this book. The appearance of the dried cover and text was equivalent to that observed previously. The sandwich technique was applied successfully. 

Dielectric (12- and 27-MHz) and microwave (2450-MHz) radiation can be used successfully for high-speed drying of uncoated paper when the electrical conductivity of pigments, adhesives, and cover materials is less than that of the paper. In these investigations, the 27-MHz frequency was found to be more effective than the 12- or 2450-MHz frequencies. 

The major contribution of dielectric energy to the restoration effort was its use in thawing all file materials and nonrare books and pamphlets. They could be identified by the librarians, and their restoration could be planned by the conservator. Use of dielectric energy offers an efficient method of drying those books which could be replaced if charring might occur. The frequency of damage for this technique as applied to uncoated-paper books was 0.5%. 

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