Printing papers, paper grades

Paper is made in a wide variety of types and grades to serve many functions. Writing and printing papers constitute ca 30% of the total production. The balance, except for tissue and toweling, is used primarily for packaging (qv). Paperboard differs from paper in that it generally is thicker, heavier, and less dexible than conventional paper. 

These rosin-based sizes, whether paste, Hquid, or emulsions, can be used to size all grades of paper that are produced at acid pH. The latter include bleached or unbleached kraft Hnerboard and bag paper, bleached printing and writing grades, and cylinder board. In addition, polyaluminum compounds have been used in place of alum, most notably, polyaluminum chloride (48), which can reduce barium deposits where these have been a problem. The barium chloride by-product is more water-soluble than barium sulfate. Other polyaluminum compounds such as polyhydroxylated forms of alum and polyaluminum siHcosulfate have been evaluated as alum replacements. 

Heat as for PCTEA. Dilute 1 + 100 for use. The negatives will look thinner and of lower contrast to the eye than to the printing paper, and lower in contrast to VC than to 2-graded paper. If you use a 10% sodium sulfite solution to dilute the stock, you will have a developer similar to D-76. You can experiment with different proportions of stock, sulfite solution, and water. 

High-quality paper grades for printing are produced, on the paper machine or in a separate process, by coating the sheet surface with a concentrated dispersion of... 

Old manuscripts printed on high grade paper with acid inks, in particular the iron inks commonly used in the Middle Ages, showed significantly greater deterioration than manuscripts printed with neutral or alkaline inks (2). 

The furnish of a paper machine varies widely, depending on the grade of paper being made. Newsprint usually consists of about 80 percent groundwood and 20 percent chemical fiber (sulfite or semibleached kraft). Bag papers and linerboard are usually 100 percent unbleached softwood kraft. Printing papers are made from bleached pulps and contain both hardwoods and softwoods. By selecting the proper pulps and refining conditions, a wide variety of paper qualities can be achieved. 

Table II. Standard and non-standard physical test measurements of various commercial grade printing papers (determined at 23°C and 50 relative humidity).

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