11. OPEN SOURECE HARDWARE¶

INSPIRATION¶

The Kombucha 3D printer of fibers A previous fabricademmy project where they created a machine to print fibers by using electrospinning principle. To print bioplastic and kombucha fibers

Kristin Arzt - Mordant Printing
Atelier Māya – Berlin’s Sustainable Block Printing & Natural Dye Atelier
Addwood Project - 3D printing stardust from woodprinting leftovers
Rachel Bakewell - Recipes For Natural Dyeing & Fabric Printing
Aristarco Cortes - Fabricademy student - Printing with CMC cellulose as thickener

STAMPING WITH CNC¶

Group Work

This week, our group advanced a project initiated by previous Fabricademy students, using CNC machine to stamping on fabrics.

We divided into groups to share task

Developing Rhino/Grasshopper code to control machine movement.
Designing a fixture to attach the stamp to the CNC head.
Building a motor and Arduino system for stamp rotation, triggered by a button.
Creating stamp designs, constructing the stamps
preparing suitable inks, and preparing fabric for printing.

The overall documentation can be found at our group google presentation

Mordant Printing with soy milk¶

We used soy milk as a natural binder on silk so that color “sticks” locally and does not flow uncontrollably, allowing clear printed patterns instead of bleeding and producing blurred edges.

Preparing the soy milk binder

Cook soybeans in a small amount of water until soft, then blend them with a hand blender into a smooth, hummus‑like paste.
Push this paste through a cheesecloth to separate the liquid: this strained liquid is your fresh soy milk for binding.
Soy milk acts like a plant‑based mordant: its proteins help the fibers hold onto dye more strongly, similar to how traditional metal mordants work, but in a gentler way.

Thickeners

To control bleeding, the soy milk is mixed with different thickeners and compared.

The following versions are prepared and tested on silk:

Pure soy milk
Soy milk + guar gum
Soy milk + xanthan gum
Soy milk + alginate

Thickeners like guar gum or similar gums make the soy milk more viscous, so the liquid stays more on the surface and bleeds less into the fabric, which helps keep sharper lines when painting or printing.

Application on silk

Using a brush, paint each of the four mixtures onto a test piece of silk in separate areas so the differences will be visible later.
Let the soy milk layers dry completely; additional layers can be brushed on top of the first to build up more binder and create a stronger effect, comparable to going over an area several times with regular textile color to intensify it.

Dye bath and pattern development

After the soy‑treated silk has dried, place the fabric into a dye bath.
The areas where soy milk (with or without thickeners) was applied will take up more color and appear stronger and darker, because the protein‑rich binder helps the dye attach more effectively to the fibers.
In this way, the painted soy milk zones become printed patterns: the contrast between treated and untreated fabric emerges during dyeing, giving clear designs without relying on metal mordants.

Discharge Printing Paste¶

For discharge printing, we prepared a printing paste based on citric acid, water, and a thickener to enable negative printing effects on dyed fabrics.

Recipe

100 ml water
5-10 g citric acid
1 g guar gum

Citric acid acts as the discharging agent, which can effectively remove color from certain dyes when printed and cured, while guar gum provides the necessary viscosity for printing it with a stamp.

Direct Fabric Printing¶

Coreopsis Ink

We prepared an ink from a coreopsis dye bath, experimenting with different thickeners to be able to stamp on fabric:

Test 1: 50 ml coreopsis dye + ½ teaspoon xanthan gum (inspired by reference video techniques).
Test 2: 100 ml coreopsis dye + ½ teaspoon alginate.

Cecilia recommended adding a metal salt to the ink to enhance stability and prevent bleeding on fabric. This ink formulation should only be tested on scoured (pre-cleaned) fabric. Application on alum-mordanted fabric does not work, as it would cause bleeding because the alum in the paint would not have any effect anymore.

Preparing stamps¶

Flora prepared the design of the stamps in Rhino and lasercut the shapes auf out EVA foam. We tried 2 mm and 6 mm EVA foam. It turned out that the 6 mm works best.

Stamping with CNC¶

Preparation of the Print bed

To create a softer printing surface, we used a layer of foam covered with felt. The foam was secured to the CNC bed using double-sided tape, and then the felt was fixed on top with double-sided tape as well. The fabric was pinned tightly with tension onto these layers to ensure stability during printing.

At the corner of the printing bed, we placed our ink jar. Maddy 3D-printed a square container, where we inserted a sponge soaked with ink. Using the code prepared in Rhino, we bypassed the need for VCarve software and directly uploaded the code to the ShopBot.

Calibration & ShopBot

We began by calibrating the machine position on the X and Y axes and set the job origin at the center of the ink jar. We measured the distance from the ink jar’s center to the first stamp's center on the fabric and input this into the ShopBot to ensure precise positioning.

For Z-axis calibration, the milling bit was positioned not to touch the bed. To achieve this, the stamp holder was set lower than the milling bit. During calibration, we placed a piece of 3cm wood on the foam, calibrated, then removed the wood, ensuring the Z-axis zero point was about 3 cm above the foam and felt layers. More details can be found in week 10 documentation.

The printing sequence run by the ShopBot was as follows: starting at the ink jar center, the head lowers on the Z-axis, pauses for 3 seconds to soak ink, then rises and moves to the stamp center. The head then lowers slightly (to -0.01) to press the stamp onto the fabric, pauses 3 seconds for printing, rises, returns to the ink jar, and moves to the next stamp position.

We adjusted settings to improve results: initial Z-axis pressure at 0.01 was insufficient, so we incrementally increased it to 0.5. Initially, a 2mm EVA foam stamp was used but caused ink bleeding; switching to 6mm EVA foam yielded better results and allowed for greater pressure to be applied. The pause was extended to 5 seconds to allow better ink transfer.

Printing was conducted on mordanted fabric using natural ink mixed with guar gum for better viscosity and adherence. For the test we put a paper on top of the fabric to keep the fabric for our final stamps.

Inks & Ink jar We tested different types of jars and materials for holding the ink.

First, we tried using a sponge, but small air bubbles appeared on the surface of the stamp. Then we tried scuba-diving fabric, which also absorbed the ink but had a smoother, more closed surface. Finally, we tested felt, to see how it absorbes the ink the best.

We tried the stamping with the different kinds of inks we prepared. It turned out that the ink had to be more liquid then expected to print properly.

We realised that we were testing many components at the same time, which made it difficult to compare the results, as we kept changing the stamping pressure, the ink pad, and the type of ink.