Aging kraft

Fig. 1. Projected rotational velocity in the Hyades and lithium versus effective temperature in 3 open clusters of the same age (Hyades, ComaB, Praesepe). The open symbols are the observed data (Kraft 1965, Stauffer et al. 1987, Mermilliod 1992, Burkhart Coupry 1998, 2000, Boesgaard 1987). The black symbols are the predictions of the rotating models at the age of the Hyades (compilation of Talon Charbonnel 1998 and Charbonnel Talon 1999)...

Of the two test papers employed in this study, the wood pulp waterleaf better represents natural cellulose, while Foldur Kraft paper, which is sized with alum-rosin, is fifteen years old and also fairly acidic, more closely resembles average library book paper. Both the papers were aged as sheets freely suspended on a rack, as... 

Figure 3 Effect of relative humidity on fold endurance of Foldur Kraft sheets aged at 90°C.

Effect of relative humidity on brightness of Foldur Kraft paper aged aa sheets and books at 90 5 ... 

A color palette for various shades of browns (obviously the most useful for repair of aged papers) has sometimes been achieved through the use of different kinds of unbleached fibers such as unbleached kraft, linen, or cotton. At this point, however, it should be pointed out that pulp designed for use in book repair may differ in its requirements from that used on art objects. Pulp used on art objects must withstand continual exposure to light without significant alteration in color. Unbleached kraft, linen, or cotton fibers tend to become lighter with prolonged... 

For each paper, both Foldur Kraft and newsprint, there were ten sample sets and one unwashed set, which was used as a control. The air dried samples were subjected to accelerated aging in humid (90°C/50% relative humidity) and dry (100°C) circulating air ovens for one, two, three, and five weeks. At regular seven-day intervals one sheet from each sample set was removed and tested. 

Table V. Aging Tests on Washed Paper, Effect on Brightness, Foldur Kraft Paper...

Several empirical and semiempirical equations were applied to folding endurance and reflectance data from Kraft paper samples aged at 70-100°C. For both properties, better fits to the data were obtained with a plot of the logarithm of the property versus the square root of aging time rather than the aging time itself. Several schemes with consecutive, competitive, or reversible reactions also were considered, and from them equations were derived that also could describe the change of properties of paper with time. 

T his chapter is a report of the results of conventional testing pro-cedures carried out on a series of kraft paper samples at the Library of Congress. The chemiluminescence emission from the paper samples was measured concurrently in a study at Battelle s Columbus Laboratories, and the results of that study have been presented elsewhere (1). In summary, the chemiluminescence maxima from the papers in humid or dry atmospheres adhered fairly well to a conventional Arrhenius expression from 25° to 100°C, which suggested a continuity in the oxidative mechanism over this temperature range, at least in the initial stages of aging. 

Table VII. Foldur Kraft pH 4.9 Aged in 100°C Dry Oven, Washed and Alkalized with Mg(X>3...

In this experiment, four types of papers were subjected to accelerated aging. The papers, Foldur Kraft, newsprint, JCPA-60 (Government Printing Office property No. 16929), and Allied Superior were placed in a... 

Table II. Comparison of Aged Foldur Kraft Paper Treated with Magnesium Bicarbonate Solution with Aged Untreated Foldur Kraft Paper Under Various Relative Humidity Conditions, Average Number of Folds (MIT 1/2 kg Tension)...

Some Foldur kraft samples were preaged before borohydride treatment and further aging. Paper samples were subjected to accelerated aging at 100 °C in a dry oven for 14 h or at 90 °C and 50% rh for 7 h. 

Table V. Effect of Calcium Hydroxide Wash Concentration on Aging of Foldur Kraft Paper ...

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