染布問題...Dyeing question,Help!

I would like to tell you the whole concept for cotton dyeing because your question doesn't specify a particular scope of cotton dyeing

Cotton dyeing can be in different forms--(i)cotton fiber-- is called top dyeing, or (ii) cotton yarn--is called cone dyeing or beam dyeing, or (iii)cotton fabric--is called fabric piece dyeing, or (iv)cotton garment--is called garment piece dyeing with two types, i.e. woven garment piece dyeing and knitted garment piece dyeing
(i)Cotton fiber dyed first and following with the processes of yarn spinning and weaving (or circular knitting) for mélange effect when the dyed fiber mixed with other fibers or any undyed fiber
(ii)Cotton yarn dyed first and following with the process of weaving (or circular knitting) for Yarn Dyed Stripe and Plaid effects on fabric
(iii)Cotton fabric piece (batch by batch in big lots) dyed--cotton fabric is woven as greige goods first (it is uncolored or raw white) with starch on its warps then dyeing the fabric after some preparation processes for quality refining. i.e. singeing, scouring, desizing the starch and semi-bleaching are required
(iv) Both semi-bleached and raw white after removed the starch, this woven and knitted garment can be dyed in pieces in small lots that cater for customers who require many color assortments but small lot like Benetton. This dyeing method would only allow one color appeared on one garment piece (single coloration)
Above are different applications of dying different forms of textile goods for the question-C

This answers to the question-A
There are several common dye stuffs for cotton dyeing namely
(i) Naphthol dyes are also called azoic, insoluble azo, ice or ingrain dye. Although these dyes have many advantages such as economic cost, easy application, bright color effect, good color fastness to laundering and perspiration, but from poor to good fastness vary in light and crocking, all have been banded in the 1980's in the world as a result of possible stimulating skin cancer when touched and bladder cancer when sucked
(ii) Reactive dyes have good property of bright shade, good to excellent fastness to light, laundering, perspiration and crocking, but poor fastness to chlorine bleach and bulk color matching to specimen is not easy
(iii) Sulfur dyes have dull shades, and are mostly navy, black and brown. They have excellent fastness to light, laundering, and perspiration, but also poor fastness to chlorine bleach. Fabric will be weakened after long time storage as residue of the dye would change to be sulfuric acid which could damage to celluloses.
(iv) Vat dyes have superior good color fastness to light, laundering and perspiration, and exceedingly fast to chlorine and other oxidizing bleaches (H2O2), and durable to crocking, but few color shades are available and dye to match is also difficult
(v) Pigment is not a dye but colored particles is mechanically bonded to fiber or fabric surface by resins, therefore heavy shades tend to stiffen fabric--harder hand feel. It is excellent fastness to light but very poor in crocking and laundering. Colors will be fading and ageing looked after wearing and washing for a period of time.

Answer to the question-B
The preparation processes are required when cotton fabric piece dyeing process is applied as (iii) form
Because this cotton fabric is firstly woven as greige goods or called loom state fabric as it is uncolored or raw white fabric with very heavy starch on its warps that is undyeble, so the starch must be removed before any dyeing process apply.
Some preparation processes for greige fabric quality refining. i.e. singeing, scouring, desizing the starch and semi-bleaching for improving the ground fabric before coloration are essential to high quality cotton dyeing

There are many forms of yarn dyeing. Common forms are -at package form & at hanks form. Cotton yarns are mostly dyed at package form, and acrylic or wool yarn are dyed at hank form
The common dyeing process of cotton yarn with reactive dyes at package form is given below in short- firstly the raw yarn is wonded on spring tube to achieve package suitable for dye penetration. then, these softed packages are loaded on a dyeing carrier's spindle one on other. then, the packages are pressed up to a desired height to achieve suitable density of pkg. then, the carrier is loaded on dyeing machine and yarn is dyed. after dyeing, the packages are unloaded from the carrier in to a trolly. then, all the packages are hydro extracted to remove maximum amount of water. then, all the packages are dried to achieve the final dyed package. at last the dyed yarn packages are packed and delivered.