. Pulp and paper magazine of Canada. gh as fine stuff all particles be-low this size (,) and it woidd be possible tohave a powder whose average particle was twice thediameter of the average fibre and still go entirelythrough the 200 mesh sieve. Bearing in mind that thefibres average about . in width or thicknessand the news sheet about , such a powderwould be a hopeless material to use. The above sketches illustrate the relation of size ofparticle to thickness of fibre. The sketches were madeto scale under a magnification of about 70 diametersand illustrate ground wood and
. Pulp and paper magazine of Canada. gh as fine stuff all particles be-low this size (,) and it woidd be possible tohave a powder whose average particle was twice thediameter of the average fibre and still go entirelythrough the 200 mesh sieve. Bearing in mind that thefibres average about . in width or thicknessand the news sheet about , such a powderwould be a hopeless material to use. The above sketches illustrate the relation of size ofparticle to thickness of fibre. The sketches were madeto scale under a magnification of about 70 diametersand illustrate ground wood and .sulphite fibres plusground talc. The Talc was a mixture of sixteen dif-ferent samples from various makers, which, as shown 306 PULP AND PAPER MAGAZINE September 15lh, 1!U6 in Table A eoiitaiiied about 28 per eent of eoarse part-icles and it is these coarse particles which are shownin the sketch the finer particles being too small tosketch properly. The larger particles shown are aswide as the thickness of the sheet of news and the. apparent result on the machine would be pinholes orfluff, or both, according to the amount of filling used. It seems im[K)ssible to supjiose that such materialcan be used except in very small amounts on the newsmachine and give satisfactory results as comparedwith china clay. If a clay or talc contains a considerable percentageof particles whose diameter is greater than, or approx-imate to the width of the average fibre, it would ap-pear to be quite unsuitable for use as a filling materialparticularly on unsized news. The average sample of ground talc is of this the other hand, all clays, even the crudest samplescontains a large percentage of really fine stuff, that isparticles that are small or very small as compared withthe diameter of a fibre. The figures below give an idea of the relative pack-ing Aveights of various clays taking water, as the unit: I Pennsylvania clay = 2 Cornish clay = Pennsylvania clay = 4 Canadian C
Size: 2735px × 914px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectpaperma, bookyear1903
