Direct dyes are a class of hot water dyes for use on cellulose fibers, such as cotton. It is one of the two types of dyes that are mixed in 'all purpose dyes' such as Rit, Tintex Hot Water dye, and Dylon Multi-purpose Dye. (The other type in the mixture is an acid dye, which will not stay in any cellulose fiber for long.) Try to find them pure, without the useless (for cotton) and money-wasting acid dyes mixed into the 'all-purpose' dyes.In most cases, better results will be obtained, often with versatile and easier-to-use cool water methods, if you use fiber reactive dye instead of direct dye.
However, there are some cases in which direct dye is preferred.
Duller in color and poorly washfast
The colors of most direct dyes tend to be duller than those provided by fiber reactive dyes, especially after fading in the laundry. The washfastness of direct dyes is poor: expect anything dyed with them to 'bleed' forever. They lack the permanence of the cold water fiber reactive dyes which most hand-dyers prefer for use on cellulose fibers. As a result, clothing dyed with direct dyes should be laundered in cool water only, with closely similar colors. The washfastness problem can be reduced by following dyeing with the use of a cationic after-treatment such as Retayne.
Inexpensive
The main reason why direct dyes are used is because of cost. Although the widely available all-purpose dyes which contain a mixture of direct and acid dyes are very expensive, per pound of fabric to be dyed, direct dyes sold alone and purchased in bulk are among the cheapest of all dyes.
Single dye bath
Direct dyes are applied in hot water, typically between 175°F and 200°F. They can be applied in the same boiling-water dyebath with acid dyes (whether for same-color effects, as in all-purpose dyes, or contrasting effects, as in the case of AlterEgo brand dyes).
Lightfastness
Direct dyes are not generally more lightfast than fiber reactive dyes; many direct dyes are less resistant to light than similarly-hued fiber reactive dyes, and both tend to be less lightfast than vat dyes. There are just a few cases in which a particular direct dye may be more lightfast than similar shades of fiber reactive dyes (see About Lightfastness). For example, Colour Index Direct Orange 39 and Direct Blue 86 are quite reasonably lightfast, with a rating of 6 (on a scale of 1 to 8). While some fiber reactive oranges are as lightfast, not all are; the popular Colour Index Reactive Orange 4 rates only 4 on that scale, while the Turquoise Reactive Blue 140 rates 5-6 on that scale.
Unfortunately, the cationic dye fixatives, such as Retayne, that are required to render the washfastness of direct dyes acceptable also reduce lightfastness somewhat.
However, there are some cases in which direct dye is preferred.
Duller in color and poorly washfast
The colors of most direct dyes tend to be duller than those provided by fiber reactive dyes, especially after fading in the laundry. The washfastness of direct dyes is poor: expect anything dyed with them to 'bleed' forever. They lack the permanence of the cold water fiber reactive dyes which most hand-dyers prefer for use on cellulose fibers. As a result, clothing dyed with direct dyes should be laundered in cool water only, with closely similar colors. The washfastness problem can be reduced by following dyeing with the use of a cationic after-treatment such as Retayne.
Inexpensive
The main reason why direct dyes are used is because of cost. Although the widely available all-purpose dyes which contain a mixture of direct and acid dyes are very expensive, per pound of fabric to be dyed, direct dyes sold alone and purchased in bulk are among the cheapest of all dyes.
Single dye bath
Direct dyes are applied in hot water, typically between 175°F and 200°F. They can be applied in the same boiling-water dyebath with acid dyes (whether for same-color effects, as in all-purpose dyes, or contrasting effects, as in the case of AlterEgo brand dyes).
Lightfastness
Direct dyes are not generally more lightfast than fiber reactive dyes; many direct dyes are less resistant to light than similarly-hued fiber reactive dyes, and both tend to be less lightfast than vat dyes. There are just a few cases in which a particular direct dye may be more lightfast than similar shades of fiber reactive dyes (see About Lightfastness). For example, Colour Index Direct Orange 39 and Direct Blue 86 are quite reasonably lightfast, with a rating of 6 (on a scale of 1 to 8). While some fiber reactive oranges are as lightfast, not all are; the popular Colour Index Reactive Orange 4 rates only 4 on that scale, while the Turquoise Reactive Blue 140 rates 5-6 on that scale.
Unfortunately, the cationic dye fixatives, such as Retayne, that are required to render the washfastness of direct dyes acceptable also reduce lightfastness somewhat.
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