980
I N D U S T R I A L A N D Eh'GINEERIiVG CHEMISTRY
Vol. 17, S o . 9
Soft Sugar Color Standards' By H. I. Knowles ATLANTIC SUGAR REFINERIES, LTD.,ST. JOHN,N. B.
OFT or brown sugars are often classified and sold on the basis of coloring matter content, as indicated by the depth of color. For purposes of comparison and grading standard soft sugars are generally used. The series consists of soft sugars of approximately equal gradations of color from almost white to dark brown. Soft sugars, however, quite readily undergo changes in color which impair their value as color standards. In addition, duplication of such standards is by no means easy or always possible. For these reasons the writer attempted to prepare artificial soft sugar color standards which would be inore serviceable.
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Requirements
A soft sugar color standard should be reasonably perinanent; it should simulate faithfully the sugar to be coinpared; exact duplication should be possible; and its application should be practicable. Of these requirements, that pertaining to faithful imitation is the most difficult to fulfil. Soft sugars made from different sources of raw sugar will differ somewhat in shade. There are other factors. such as the character of liquor and sirup used and the activity of the bone black, which influence the color of the soft sugar produced. Fortunately, however, soft sugars manufactured by refiners using the same system and similar raws will not differ in color sufficiently to make grading with the same set of standards impracticable. Ingredients
Experiments with dyed materials, including soft sugar, were not successful. It was then decided to ube granulated sugar as a base, to color it with powdered pigments, and to add sufficient Russian oil to give the mixture the characteristic soft sugar appearance. Here were three substances which by themselves were reasonably permanent and probably as permanent when mixed. It was found, moreover, that imitation soft sugars made from these materials filled the other requirements set forth; and since they have proved useful, their preparation will be briefly described. Preparation
Since relatively small quantities of pigment are used, it is more accurate and convenient to prepare a large quantity of colored sugar, which will serve as a basis for the set of standards subsequently prepared. For this purpose, 2000 grams of Coarse Powdered grade of granulated sugar are weighed into a wide, porcelain-lined dish. Weighing bottles are filled with the pigments t'o be used and the weight of each is determined. The sugar is dusted with some of each of the pigments, which are then distributed throughout the sugar by mixing with a porcelain pestle. It is now necessary to test the colored sugar in order to determine how closely it matches a real soft sugar which has been chosen as representing the average in color. A small quant,ity of the colored sugar is diluted with white sugar in a mortar and sufficient Russian oil is incorporated with the mixture to give it a wet appearance. Comparison is then made.with the soft sugar. Pigments necessary to give the desired color are added to the colored Coarse Powdered and mixed in as before. This operation of adding pigments and Presented before the Division of Sugar Chemistry at the 69th Meeting of the American Chemical Society, Baltimore, Md.. April 6 to 10, 1925. 1
making trial comparisons is continued until a close match is obtained between the real soft sugar and the artificial preparation. The weight of each pigment used is determined by reweighing. It is evidently essential that the colored sugar thus prepared be of a much deeper color than the darkest standard to be made. h set of standards is made from the colored sugar by diluting a known quantity with a weighed amount of white sugar and adding a definite volume of Russian oil. It is convenient to mix the two sugars first by rolling on a sheet of paper. It is also convenient to add the oil to the mixing dish first and to spread the oil over the surface. The mixed sugars are then added and incorporation of the ingredients effected by a combination of grinding and mixing with a pestle. This operation is important. Whether the standard will have a homogeneous or a mottled appearance depends upon the thoroughness of the Operation. To convey some idea of the amounts of the various ingredients used, the following details col-ering a set of 3tandards that have been used successfully are given. Colored Sugar Base (Coarse Powdered, Granulated, 2000 grams) PIGMENTS ADDED Grams Chrome yellow, light 15.816 Chrome yeilow, medium 13,498 Yellow ochre 6.098 Raw umber 3.739 Ultramarine Standards 0.117 Standard 10 15 20 25 30 35 40 50
Colored Sugar Grams
.
10
15 20 25 30 35 40 50
Coarse Powdered Grams 190 185 180 175 170 165 160 150
Russian Oil cc. 25 25 25 25 25 25 25 2.5
Permanence
The amount of colored sugar base is evidently sufficient, for many sets of standards and a stock of a few pounds of each of the pigments will last for years. Standards thus prepared and put up in square-faced glass bottles, provided with metal caps, have been in use more than six months. Working sets have been kept ill a box with hinged cover. Under these conditions the only change in the standards noted has been a very slight reddening in color, due presumably to the fading of the yellow pigments. This change, however, is not sufficient to require new standards. Tests indicate that a t ordinary temperatures evaporation of the Russian oil is not appreciable and therefore the standards could probably be kept in tin boxes usually used for soft sugar samples. Use
For purposes of control, a set of standards is used by the centrifugal foreman as a guide in centrifuging soft sugar skips; another set serves the superintendent in like manner; and lastly, the color tester in the laboratory is provided with a set in order that a record may be kept of the color of the different lotsof soft sugar manufactured. The Tariff Commission has ordered an investigation into methanol, under the flexible tariff, since 57 domestic wood alcohol firms joined in an application for an increase.
