Dextrin’s are normally prepared by roasting starch in the presence of acid which materially changes the character and properties of starch. Chemically they are intermediate between starch and sugars derived from starch.

Unlike starch, dextrins are soluble in water. The severity of the heat and acid treatment determines the degree of solubility, which is the basis for classifying or grading dextrins.

Finished dextrins are very fine, powder varying in colour from pure white to light yellow.As dextrins do not easily react with chemicals, they are specially suitable for application in the textile field. In textiles printing, they are used as thickeners. Free of grit and other impurities, which usually accompany lower grades of starch, they ensure that the copper rolls (used in printing) do not suffer from abrasion. In sizing, they are used with starch for increased adhesiveness. In finishing, they give desired feel and handle to the fabric.

The tack or stickiness of dextrins is increased by adding caustic soda or borax. The adhesive thus formed is widely used in various industries. In the adhesive industry itself, dextrins are preferred to glue which has an unpleasant odour and is subject to rapid bacterial decomposition. They are also preferred to starch, as they need less or no cooking and much less water to form the paste. This means reducing drying time and little likelihood of mould infection in warm climates. As adhesives, dextrins are thus used with greater advantage in book binding, carton sealing, cigarette pasting, label pasting of all kinds, paper box making, gum tapes, spiral tube winding etc. In dyestuff industry it is used as extenders.

The role of dextrins in foundries is well-known. Here the main function is to give good green strength to moulds and to prevent deformation of the core, which is considerably handled before being fired in the oven. Another important feature is that dextrins do not make the core too dense, so that there are no trapped gases which cause blow holes. All these advantages make dextrins very good as core binding materials.

Dextrins are largely used in dry distemper. 2% to 3% of dextrins mixed with chalk and pigment, acts as a carrier and imparts good adhesions of the colour to the wall.

Foundries, Distemper & Textile

50kg HDPE bags