Zinc-Formaldehyde-Sulfoxylate (ZFS) Systems
Zinc formaldehyde sulfoxylate is a reactive chemical commonly used in industrial applications for bleaching. It is also known as Rongalite (registered trademark of BASF), sodium hydroxymethylsulfinate. While its heath effects include irritation of skin, eyes and gastrointestinal tract the full toxicological properties of this material have not been fully investigated. During the heating and curing of discharge inks, formaldehyde and sulfur dioxide gases develop as by- products of the reduction process. Formaldehyde is a known human carcinogen. Proper ventilation of the ovens and/or workplace is crucial. It would be proactive to have any facilities indoor air quality checked for formaldehyde levels. Waste discharge ink, like all inks in a liquid state, is considered a hazardous waste and must be handled as such. Even though it cannot function as discharge ink after its shelf life, it can be “recycled” by using the ink as normal ink on light colored textiles. Garments printed with the ZFS discharge system can have measurable levels of residual formaldehyde that did not off gas from the garment during the curing/heating process. Garments may need to be washed or aired to remove all traces of this chemical. If garments are allowed to sit for a time after printing will outgas much of the residual formaldehyde in a few days, temperature and airflow pending – but consideration of where that formaldehyde is going is of concern if it exposes workers or others, ensure adequate ventilation. The European Union has a formaldehyde exposure threshold of 75 ppm for apparel for small children and infants. Some EU countries, Japan and other countries law is even more strict – 20ppm for children under 36 months of age. A ZFS discharged garment, which has not been laundered or allowed, to off-gas could fail these tests. Thiourea dioxide-activated Discharge Systems Thiourea dioxide activated discharge inks were developed to avoid the formaldehyde exposure and residues associated with ZFS activated discharge inks. They work in a similar fashion with thiourea dioxide as the chemical reducing agent that destroys the garments original dyestuff.
Synonyms: aminoiminomethanesulphinic acid, thiourea dioxide, formamidinesulfinic acid, formamidinesulphinic acid, as well as several trade names.
Acute health effects of thiourea dioxide include; eye irritation, chemical conjunctivitis, skin and it may cause gastrointestinal irritation with nausea, vomiting and diarrhea. But like ZFS the toxicological properties have not been fully investigated. It is important to note that thiourea dioxide is a different chemical than thiourea (without the “dioxide”). Thiourea is a chemical known to the State of California to cause cancer.
We use this ranking of different print systems to help us determine what kinds of inks we should use for a specific print job:
• Ink jet garment direct printing (with water based inks if possible) • Water based printing • Water based discharge, we prefer non-formaldehyde systems • Non-PVC/NonPhthalate inks • Plastisol inks
25
Made with FlippingBook flipbook maker