Eco printing is a beautiful and natural method of transferring botanical shapes and colors onto fabric, creating truly one-of-a-kind designs. However, to achieve vibrant, lasting results, properly mordanting your fabric is essential. Mordanting prepares the fabric to bond with the natural dyes found in leaves, flowers, and other plant materials. This step not only enhances color but also helps with washfastness and print clarity. While the word ‘mordant’ might sound intimidating, the process is straightforward and highly rewarding for anyone interested in eco printing or natural dyeing.
Understanding Mordants and Their Purpose
Before you begin, it’s important to understand what mordants are and why they matter in the eco printing process.
What Is a Mordant?
A mordant is a substance used to fix dyes to fibers. In eco printing, mordants allow plant pigments to better attach to fabric and remain vibrant over time. Common mordants include alum (potassium aluminum sulfate), iron, and tannin. Each mordant reacts differently with various fibers and plant materials, influencing color and tone.
Why Mordanting Is Important
- Improves dye absorption and bonding to the fabric
- Enhances color brightness and contrast
- Prevents prints from fading quickly
- Allows for more precise and defined leaf and flower impressions
Choosing the Right Fabric for Mordanting
Natural fibers work best for eco printing and respond more effectively to mordants. Here are common fabric options:
- Cotton: Readily available and affordable, but needs extra preparation to accept mordants well.
- Silk: Excellent absorption and detail; requires minimal preparation.
- Linen: Durable and great for printing, though it may wrinkle easily.
- Wool: Natural protein fiber with excellent dye uptake, often used with iron mordants.
Always choose untreated, pre-washed fabrics for best results. Synthetic or heavily processed fabrics generally do not take natural dyes well.
How to Scour Fabric Before Mordanting
Scouring is a crucial step to remove any oils, waxes, or manufacturing residues that can block dye absorption. Skipping this step can lead to uneven prints and poor color results.
Scouring Cellulose Fibers (Cotton and Linen)
- Fill a pot with hot water and add a few teaspoons of soda ash or washing soda.
- Submerge the fabric and simmer for 12 hours.
- Rinse thoroughly in warm water and let dry or move on to mordanting.
Scouring Protein Fibers (Silk and Wool)
- Use lukewarm water with a gentle, pH-neutral soap (e.g., Orvus paste or castile soap).
- Soak for 3060 minutes without agitating too much, as wool can felt.
- Rinse with clean water and handle gently.
Mordanting Methods for Eco Printing
Now that your fabric is clean and ready, it’s time to mordant. Different fabrics require different mordant types and methods, but the most commonly used mordant in eco printing is alum.
Alum Mordant for Cellulose Fibers
Alum (potassium aluminum sulfate) works well for cotton and linen when paired with soda ash or tannin. Here’s a step-by-step process:
- Weigh your dry fabric. The alum measurement is based on fabric weight.
- Use 1015% alum based on fabric weight. For example, for 100 grams of fabric, use 1015 grams of alum.
- Dissolve alum in hot water in a separate container.
- Add the solution to a large pot of hot water, then submerge the fabric.
- Simmer gently (do not boil) for 1 hour, making sure the fabric is fully immersed.
- Let the fabric cool in the solution overnight for deeper penetration.
- Rinse lightly or leave as-is, depending on when you plan to use it.
Alum Mordant for Protein Fibers
Silk and wool respond well to lower concentrations of alum:
- Use 10% alum based on fabric weight.
- Dissolve in hot water and stir gently.
- Submerge pre-wet fabric and heat slowly to simmer for 4560 minutes.
- Allow fabric to cool in the solution before removing and drying.
Iron Mordant (Iron Sulfate)
Iron is used sparingly, often as a modifier to shift colors toward deeper or more muted tones. Be careful too much iron can damage fabric or produce muddy prints.
- Use 12% iron based on fabric weight.
- Dissolve iron sulfate in hot water.
- Soak fabric for 1530 minutes, stirring occasionally.
- Rinse and dry or use immediately for printing.
Iron can also be added after printing to modify colors, known as post-mordanting.
Tannin Pretreatment (Optional for Cellulose)
Tannin helps cotton and linen fabrics accept alum better. It can also shift colors to warmer browns or greys.
- Use 1015% tannin based on fabric weight.
- Dissolve in hot water and soak fabric for 12 hours.
- Rinse and proceed with alum mordanting.
Drying and Storing Mordanted Fabric
Once mordanting is complete, you can either use the fabric right away or store it for later use. Follow these best practices:
- Air-dry fabric away from direct sunlight.
- Label each piece with the mordant used for future reference.
- Store in a cool, dry place if not printing immediately.
Important Safety Notes
While mordanting uses mostly natural or low-toxicity substances, it’s important to follow safe practices:
- Wear gloves when handling mordants, especially iron or copper compounds.
- Use dedicated pots and utensils for dyeing don’t reuse them for cooking.
- Work in a well-ventilated area and store mordants out of reach of children or pets.
Preparing for Eco Printing After Mordanting
Once your fabric is properly mordanted and dried, you can start the eco printing process. Arrange leaves and flowers on the fabric, roll or fold it tightly, and steam or boil to transfer the natural pigments. The mordanting step ensures that the natural dyes bond to the fabric, resulting in clear and vibrant botanical prints.
Mordanting fabric is a crucial step in eco printing that significantly affects the final outcome. By carefully choosing the appropriate mordant for your fabric type and following proper techniques, you set the stage for beautiful, long-lasting botanical prints. Whether you’re using alum for cotton or experimenting with iron for darker tones, the effort you put into mordanting will directly reflect in the quality and clarity of your finished eco prints. With practice and attention to detail, you can create stunning natural art on fabric that showcases the beauty of nature in every leaf and petal.