Reactive dyes occupy a very important place in textile printing, especially for cellulosic fibres such as cotton and viscose. Among them, Procion reactive dyes are well known because they can produce bright shades with good washing and light fastness.
For a textile student, Procion dyes are also interesting because they connect three things together:
Procion dyes are a class of reactive dyes. They are called reactive because they do not merely deposit colour on the fibre surface. Instead, they react with the cellulose fibre and form a chemical bond.
This is the key idea.
In many dyes, the colour may remain attached to the fibre through physical attraction or weak forces. But in reactive dyes, the dye molecule chemically combines with the fibre. Because of this, the print becomes more durable.
This chemical bonding is the reason why Procion dyes generally show good fastness properties.
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Cotton and viscose are both cellulosic fibres. Their structure contains hydroxyl groups, which can react with reactive dyes under suitable alkaline conditions.
That is why Procion dyes are mainly used for printing fabrics such as:
When the right amount of alkali, moisture, temperature and time are provided, the dye reacts with the fibre and becomes fixed.
Since the dye forms a chemical bond with the fibre, the printed colour can withstand washing better than many non-reactive dye systems.
Procion dyes also give reasonably good resistance to light, depending on the shade and dye selection.
Reactive dyes are known for producing clear and bright shades. This makes them suitable for printed dress materials, sarees, furnishings and many other cotton-based products.
Different Procion dyes can be combined to obtain a wide variety of colours and tones.
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Procion dyes can be broadly divided into three classes:
The main difference between them is their reactivity.
Reactivity means how quickly and easily the dye reacts with the fibre.
Procion-H dyes are the least reactive among the three groups.
Because they are less reactive, the printing paste prepared with them remains stable for a longer time. This is useful in textile printing because printing paste may have to remain usable during production.
However, because Procion-H dyes are less reactive, they need proper fixation conditions. They are mainly suitable where fixation is done by the steaming process.
Procion-H dyes are slow-reacting but stable.
So, they are useful when:
Procion-Supra dyes are more reactive than Procion-H dyes.
They give good washing fastness and are useful where somewhat higher reactivity is needed.
Procion-Supra dyes can also be used along with Procion-H dyes in many cases.
Procion-Supra dyes are a middle category.
They are more reactive than Procion-H, but they still offer reasonable process stability.
Procion-M dyes are highly reactive.
Because of their high reactivity, they are widely used in textile printing. They can be used not only in steaming processes but also in certain methods where steaming is not used.
They are also suitable for resist-style printing.
However, there is one important caution.
Because Procion-M dyes are highly reactive, their printing paste does not remain stable for a long time. Therefore, Procion-M paste should be prepared only in the quantity required for immediate use.
Procion-M dyes are fast-reacting dyes.
They are useful when:
| Dye Type | Reactivity | Paste Stability | Main Use |
|---|---|---|---|
| Procion-H | Low | High | Mainly steaming process |
| Procion-Supra | Medium | Good | Printing where better reactivity and fastness are required |
| Procion-M | High | Low | Quick fixation, resist style, wider process use |
Most Procion dyes are compatible with one another and can be used to produce many shades.
However, one practical point is important:
This is because their reactivity levels are quite different. One reacts slowly, while the other reacts quickly. This difference may create problems in shade development and fixation.
On the other hand:
In textile printing, the dye cannot be applied like a simple liquid. It has to be converted into a paste so that it remains on the printed area and does not spread uncontrollably.
For this purpose, a thickener is used.
For Procion reactive dyes, the commonly used thickener is:
Sodium alginate is preferred because it is suitable for reactive dye printing. It helps create a smooth printing paste and does not interfere seriously with the dye-fibre reaction.
A good thickener should:
This is why sodium alginate is generally used for Procion dyes.
A printing paste for Procion dyes generally contains:
Each ingredient has a specific role.
This is the colouring matter. It reacts with the cellulosic fibre and gives the desired shade.
Urea helps in dissolving the dye and retaining moisture during fixation. Moisture is important because the dye-fibre reaction needs suitable conditions.
For cotton fabrics, urea is generally used in the range of:
For viscose fabrics, it is generally used in the range of:
The exact amount depends on the process and steaming conditions.
Water dissolves the dye, urea and alkali and helps in preparing a workable paste.
Sodium alginate acts as the thickener. It gives body to the printing paste and helps produce clean printed designs.
Resist salt helps prevent unwanted effects during printing, especially in roller printing and discharge-related situations. It also helps control unwanted reduction or discharge effects.
Alkali is essential for the reaction between Procion dye and cellulose fibre.
Without alkali, the dye may remain only deposited on the fabric and may not properly react with the fibre.
Common alkalis include:
The choice of alkali depends on the dye type and process.
A stock thickening paste is first prepared, generally using sodium alginate. The required dye is then added and mixed thoroughly. A high-speed stirrer is used so that the ingredients are properly dispersed.
| Ingredient | Stock Paste | Reduction Paste |
|---|---|---|
| Procion dye | 50 parts | — |
| Urea | 50–200 parts | 50–200 parts |
| Water | 490–240 parts | 540–290 parts |
| Sodium alginate thickener | 350 parts | 350 parts |
| Resist salt | 10 parts | 10 parts |
| Alkali: sodium bicarbonate or sodium carbonate | 25 parts or 15 parts | 15 parts |
| Total | 1000 parts | 1000 parts |
One common method is as follows:
The paste should be smooth, uniform and free from lumps.
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Paste stability is very important in printing.
The paste of Procion-H and Procion-Supra dyes can remain usable for a longer time, up to about 28 days.
But Procion-M paste is not stable for long because the dye is highly reactive.
This is a very practical point in production. If highly reactive dye paste is stored for too long, the dye may lose its effectiveness, and the print quality may suffer.
Procion dyes are reactive dyes used mainly for printing cotton and viscose fabrics. They form a chemical bond with cellulose fibre and give good washing and light fastness.
The three main types are:
Sodium alginate is commonly used as the thickener. Urea, alkali, resist salt and water are important ingredients in the printing paste.
The most important technical point is that reactivity and paste stability are connected. A highly reactive dye like Procion-M works quickly but has lower paste stability. A less reactive dye like Procion-H is slower but more stable.
In reactive dye printing, alkali is not just an additive. It is the chemical trigger that allows the dye to react with cellulose.
Without alkali, the dye may colour the fabric, but it will not be properly fixed.
A common mistake is to treat all Procion dyes as if they behave the same way.
They do not.
Procion-H, Procion-Supra and Procion-M differ in reactivity, paste stability and suitable fixation method. Understanding this difference is essential for successful printing.
Why should Procion-M printing paste be prepared only when required, while Procion-H paste can remain usable for a longer time?
The answer lies in one word:
Reactivity.
Disclaimer and Safety Note: This article is intended for educational and informational purposes only. The recipes, chemical names, quantities, temperatures and process conditions mentioned here are provided to explain the principles of Procion reactive dye printing and should not be treated as direct instructions for unsupervised practical use. Textile printing involves the use of dyes, alkalis, salts, thickeners and other auxiliary chemicals, which should be handled only with proper knowledge, suitable safety precautions and appropriate supervision. Before using any chemical, always refer to the latest supplier technical data sheet, safety data sheet and applicable local regulations. Use appropriate personal protective equipment, ensure good ventilation, safe storage, careful measurement, spill control and responsible disposal of chemical residues and wastewater. The author and publisher do not accept responsibility for any loss, damage, injury or environmental harm arising from the direct or indirect use of the information given in this article, and readers are advised to consult trained textile processing professionals before attempting any laboratory or industrial application.
Continued in Part-2
