Stains. When we observe stains produced by mordants, upon spots where no colour is to come, we must, before dunging the goods, apply a little of the lime juice, or tartaro-oxalic acid discharge paste, to the place. If, on the contrary, the stains are not perceived till after the maddering, we must then apply to it first a strong solution of chloride of lime with a pencil, next a solution of oxalic acid mixed with a little muriatic with another pencil, and immediately afterwards wash with water. Every madder stain will be effaced by this means.
Rust stains are removable by a mixture of oxalic and muriatic acids.
Indigo stains by the combined action of chloride of lime and muriatic acid.
Topical yellow stains, or yellow dyes, by the same combination.
Metallic greens and Scheele’s green by the acid alone.
Chrome green, and Prussian blue. The blue may be taken out by a caustic alkali; after which the goods must be washed: the residuary rust stain may be removed by the mixture of oxalic and muriatic acids. The above methods refer to cotton and linen. The stains on silk and woollen stuffs should be removed before fixing the colours by the soap boil; which may generally be done by scratching with the finger, with the aid of a little water.
For a direct calico green, see [oxide of Chrome].
Mr. Hudson, of Gale, near Rochdale, obtained a patent, in December, 1834, for a mechanism which furnishes a continual and regular supply of colour to the sieve or tear (tiré, Fr.) into which the printer has to dip his block, for the purpose of receiving the colour about to be transferred to the fabric in the operations of printing calicoes or paper hangings. The contrivance consists in a travelling endless web, moved by power, which, by passing progressively from the colour vat over the diaphragm, brings forward continuously an equable supply of the coloured paste for the workman’s block.