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Table of Contents
WARNING: toxic. Probably the most dangerous chemical you are likely to run into. Spilling high concentration on your skill can make you die a horrible death.
Sourcing
Whink rust stain remover
~2.5% HF solution can be found in Whink brand rust remover. Unfortunately, due to health concerns with HF, this product is not sold in the EU. You still might be able to order it from somewhere overseas (ie eBay) cheap enough.
| Chemical | CAS | Weight % |
|---|---|---|
| Water (H2O) | 7732-18-5 | 90 - 100 |
| Hydrofluoric acid (HF) | 7664-39-3 | 1.50 – 3.5 |
| Denatonium Benzoate | 3734-33-6 | 0.01 – 0.10 |
Denatonium Benzoate is a bitterant probably put in to make sure that nobody consumes the HF.
RustGo
MSDS: http://www.alwilson.com/products/rustgo/RustGo%20MSDS.pdf
| Chemical | CAS | Weight % |
|---|---|---|
| Hydrofluoric acid (HF) | 7664-39-3 | ~12% |
| Ammonium bifluoride (NH4HF2) | 1341-49-7 | ~16% |
| Water (H2O) | 7664-39-3 | Remainder |
This states that 12% HF freezes at about 5C or so. Could the NH4HF2 be frozen out? Its very soluble in water though at 63 g / 100 mL @ 20C. For better or worse NH4HF2 also attacks SiO2.
Glass etching
I've heard it can be sourced for glass etching. The stuff I've seen is usually hydroxide based, and rarely some HF in paste form.
Safety
Recommend use of approved respirator. Ex: 3M 7800 with acid gas cartridges. Recommend use of gloves. Double gloving may be a good idea. Recommend keeping calcium gluconate around in case of exposure. Ex: Calgonate
Applications
Dissolves SiO2.
Suppliers
Due to this chemicals extreme toxicity it may be difficult to acquire depending where you are. Some rust removers are HF. Whink brand rust remover is a weak HF solution. At this solution data sheets indicate that it is not so deadly but it should still be treated with care. Contact me if you need to get a stronger solution brand.