Soy Ink Disposal and Recycling

Soy ink is a type of ink created by cleaning, cutting, and flaking soya beans and processing them to extract soy oil. This oil undergoes a refining process and is then blended with pigments, resins, and waxes to form soy ink. It’s a plant-based ink that can provide accurate colours but may be slower to dry than other inks.

Soy ink is used in offset lithographic printing on paper (most commonly used in commercial printing – such as for printing newspapers and magazines). Many people and businesses use soy inks for a wide range of printing and other purposes, such as:

• Printing on corrugated packaging (like pizza boxes)
• Adding designs on timber, leather, ceramic tiles
• Making some tattoo inks
• Screen printing
• In digital toners for printers

Soy ink is considered more environmentally friendly than traditional inks. This is because soybeans are a renewable resource, unlike the oil where petroleum-based inks are derived. Soy inks also reduce hazardous air pollution arising from VOCs (volatile air compounds) like toluene, benzene, and xylene – which petroleum-based inks contain.

These are gases are emitted into the air in the printing process, and which also occur when changing cleaners and solvents between printing runs. They can also cause respiratory irritation, harming the health of humans who come into contact with them. So, soy ink can be safer for the environment and people.

Soy ink also degrades four times faster than petroleum-based inks. It’s easier to remove when printed on paper too, which increases the chance of recycling paper and packaging to a higher quality.

The main disadvantage of soy ink is that it’s slower to dry than petroleum-based inks. This increases the chance of rub-off resistance and markings as it takes longer to dry. Therefore, soy ink isn’t ideal for printing glossy magazines or for use in ballpoint pens.

The main inks for printing have traditionally been petroleum-based, also referred to as solvent-based inks. Concerns have been raised about heavy metals in inks – cadmium, hexavalent chromium, lead, and mercury are all toxic. This type of ink is therefore considered hazardous waste as it can be harmful to both human and environmental health.

Soy ink is up to four times more degradable than standard ink. Unlike petroleum-based inks, it’s not a type of hazardous waste as it doesn’t contain any VOCs. Therefore, the paper on which soy ink is used is normally readily recyclable alongside your other paper waste.

Even paper and packaging printed with soy ink that ends up in landfill has a reduced environmental impact as it degrades quicker and contains no fewer hazardous elements. If you have actual soy ink to dispose of, consider giving it to someone else or another organisation that could use it. Otherwise, it may class as liquid waste.

Aside from petroleum-based and soy inks, there are various other types of ink available:

• Plastisol inks have two main ingredients – PVC resin and ‘plasticizer’. Plastisol ink will not dry at normal temperatures but must be ‘cured’ at around 300 to 330 degrees Fahrenheit. Plastisol ink is favoured for screen printing and can be toxic, although non-toxic premium brands are available.
• Water-based inks are considered to have a lower environmental impact than petroleum-based inks. Water-based inks are often used in textile printing but aren’t suitable for all types of printing.
• Vegetable inks made from canola oil, linseed oil, or rice also have a lower environmental impact. Lots of water is required to grow rice, leading to criticism of its use as an element of ink. Some companies also claim vegetable oils produce less vibrant colours.
• An innovative algae-based ink has been developed in recent years that can be used for flexographic and letterpress printing.

The American Soybean Association provides a SoySeal to licensees. This specifies the percentage of soy oil content to be used with different types of ink. These range from 40% for newspaper ink to 6% for stencil duplicator ink. Soy ink is therefore not 100% biodegradable as it uses pigments and other additives also found in petroleum-based inks.

Soy ink still has a higher element of biodegradable ingredients than traditional inks though. When used for printing labels, soy inks use less ink than water-based inks. Plus, soy inks can be reusable when mixing black inks with colour-based inks. The use of recyclable elements also minimises paper waste.

The growing use of soy ink in digital toners reduces a large amount of ink cartridge waste too.

Some key environmental impacts of traditional, petroleum-based inks are that:

• Normal ink cartridges aren’t biodegradable. Improper disposal has an impact on air quality and health.
• The disposal of petroleum-based cartridges produces VOC toxins, which are recognised as contributing to cancers and some birth defects.
• Digital inks are usually solvent- or water-based, so have different levels of environmental impact.
• Some petroleum ink is not recyclable and therefore leads to paper waste. Concerns remain regarding hazardous waste arising from traditional print processes.

The changes in the print business the use of soy ink have introduced are leading to reduced business waste. This cuts waste disposal costs and the cost of complying with environmental legislation on waste. Minimising waste makes sense for businesses, the environment, and future generations.