What is Chromium VI?
- Definition: Chromium VI (Cr6^+) is a highly oxidized form of chromium.
- Formation: It can form during tanning or aging of leather.
- Nature: It is toxic, reactive, and regulated worldwide.
Chromium III (Safe)
Chromium VI (Toxic)
Why Avoid Chromium VI in Leather?
- Regulatory Limits: International regulations limit Cr6^+ to < 3\text{ ppm}.
- Dermatological Impact: Causes skin allergies and dermatitis.
- Brand Image: Damages the reputation of leather products.
- Root Causes: Can result from poor tanning or ageing conditions.
HEAT + UV + Poor Tanning = Cr6+ Formation
Health Issues Caused by Chromium VI
- Skin Allergies: Rashes and contact dermatitis.
- Respiratory Issues: Irritation when inhaled.
- Carcinogenicity: Carcinogenic with long-term exposure.
- Sensory Irritation: Eye and mucous membrane irritation.
Human Exposure = Skin Allergy [contact dermatitis]
The Guaranteed Solution
Using Sodium Thiosulphate is a safe and effective chemical approach that neutralizes the risk of Cr6^+ formation.
How is it Used?
It is added during the dyeing process and at the end of dyeing.
The Key to Success:
- Correct Dosage: Use a maximum of 0.7\% based on the shaved weight of wet-blue leather.
- Cost-Effectiveness: This small, precise amount is both cheap and highly effective.
Guaranteed Safety
- Prevents Formation: Stops Hexavalent Chromium from forming.
- Long-Term Protection: Ensures leather stays safe even as it ages.
- The Bottom Line: This is the most convenient, cost-effective, and scientifically proven method to ensure your leather is 100\% safe and free from any Chromium six.
Guideline Recipe
Apply the following steps right after the neutralization of wet-blue:
| Step | Ingredients & Process | Action / Duration |
| 1 | 100\% water | Initialize process. |
| 2 | 0.3\% Hypo (Sodium thiosulphate) | Add to the mixture. |
| 3 | Process Continuation | Continue the process as usual, just before final fixation with formic acid. |
| 4 | 200\% water | Dilute/wash. |
| 5 | 0.15\% Hypo (Sodium thiosulphate) | Run for 15 minutes. |
| 6 | 0.5\% Formic acid | Run for 20 minutes. |
| 7 | pH Check | Check pH and unload. |
The table gives data on dimensions of Atlantic and Indian Ocean. The two oceans are similar in their average depth, on an average, the Atlantic Ocean is 3,646 meters deep and Indian Ocean is 3,741 meters deep. The area covered is similar however, Atlantic Ocean is larger at 85 million square kilometers. In contrast, the depth of the two oceans is very different, notably, the coastline of Atlantic Ocean is twice as much as Indian Ocean, a remarkable 121,866 kiiometers.
