Principles of bio-based printing on textiles

Is a technique in which biochrome thickened dye pastes or solutions are applied to a mordanted cloth, fixated through heat or in which a thickened dye paste is combined with a mordant paste and then applied. In both cases the paste is directly applied in place, with no subsequent dyeing process necessary.

The result is an untouched background, the biochromes are only directly applied where color is intended to be. An infinite amount of colours can be individually applied, extracted from different types of dye matter. No immersion dye bath is required, meaning that most of the process can be executed without the use of large dye pots.

One single dye can be overlapped for intensifying the shade or multiple can be used to create other shades and gradients. For example when overlapping a yellow from weld with a pink from cochineal, a clear orange emerges at their intersection.

The steps of the process:

• Scouring of cloth
• Mordanting of cloth
• Preparation of dye paste 
• Printing, deposition of dye paste in place
• Fixating (drying, heating)
• Rinsing

The preferred mordant for the background in this case is a neutral soda ash-type or acetate-type. The dye pastes need to be concentrated, but the actual colours will only emerge after the fixation process, often intensifying or mutating into their final shape after 1-2 fixations. Steaming is the preferred fixation process.

Is a technique in which one or more varieties of thickened mordant pastes are applied to cloth, fixated via immersion to remove the thickeners and then dyed in an immersion dye bath.

The result here of is a most often a white background (or the initial, or natural color of the cloth) with clear coloured sections where the textile was printed, even though the entire textile has been submerged into the dye bath, the dye will only bind itself with the mordanted sections. This specifically works at its best when the dye used for the immersion dyeing step does not bind to un-mordanted fibers. This depends on what typology of biochromes (dyeing molecule) is at work in the dye bath. Dyes that do not require a mordant, or that produce different stable colours on both mordanted and un-mordanted cloth, will instead result into tonal variations across the cloth.

The mordant selection in combination with the dye chosen, will determine the outcome of the colour scheme – often brighter or more intense where aluminium mordants were applied, or darker and shady where ferrous mordants were applied – meaning that each colour result is determined by the individual combinations of biochrome and mordant or biochrome and cloth. Mordant pastes can be overlapped, to create in-between shades and gradients across two mordants.

The steps of the process:

• Scouring of cloth
• Preparation of mordant paste 
• Printing, deposition of mordant paste in place
• Fixating (drying, immersion dunging)
• Immersion bath dyeing
• Rinsing
• Clearing of background

The preferred mordant for the paste in this case is a thickened acetate-type, to be utilised fresh or within 12 hours from mixing. The metallic salts tend to “eat” into the thickening agents, such as gums, breaking them down and making them unusable. Drying of the print is extremely important in this case, to retain precise areas and avoid mordant bleeds, no smell should be left onto the cloth before proceeding into the next steps. Dunging is carried out to both neutralise the acetate solutions and remove the remaining gums from the textiles. The immersion bath dyeing is carried out as any other traditional dyeing process, following the requirements of the dye matter used – caring for both correct temperature and ph parameters in order to achieve the best prints.

Especially when mordant printing ph-sensitive dyes produce different outcomes, testing these variables through a number of different ph-modifying additives is required for each dye matter type.

Mordant printing has the ability to be also used for “black-work” printing. When the ferrous mordants are used in combination with tannins a variety of shades of grey and blacks can be achieved. In this case the mordant printing happens on tanned cloth or is followed by an immersion bath into tannins.

Is a technique in which the mordant is discharged from the mordanted cloth, producing a negative space when immersion dyeing or printing. Discharging is intended as in dissolving of the bound mordant from the cloth, bringing back to its initial un-mordanted state the area of cloth that has been printed with the discharge solution. Discharge printing can also be implemented as a technique to clean up unwanted spills or marks of the mordant printing technique, before its fixation.

The steps of the process:

• Scouring of cloth
• Mordanting of cloth
• Preparation of discharge paste 
• Printing, deposition of discharge paste in place
• Fixating (drying, dunging)
• Immersion bath dyeing
• Rinsing
• Clearing of background

These techniques can be reconfigured in a number of ways, for example using direct printing after a cloth has undergone a discharge printing process; or more traditionally when using stencils and blocks, it was usual to mordant print, before fixation to discharge certain areas and mordant print again, followed by an immersion dye. Highly complex colour patterns can be achieved when these techniques are combined.