Non-nasal identification of 'off' gum arabic solution
Some time ago I posted a thread about the use of tea tree oil as a preservative for gum arabic (GA) solution. As tea tree oil is easy to source I wanted to use it for preservation of GA solution mixed from powdered GA (because I cannot source formalin or thymol). Tea tree oil is also a natural antiseptic, anti-bacterial, non-irritant and soluble in alcohol so it may provide a good alternative. As I live in the tropics GA solution with no preservative stored at room temperature usually smells worse than cat excrement after about 10 days. It also goes cloudy and / or gains a nice crust of green mould. About 3 months ago I mixed up 50ml of 26% GA solution adding 1ml of 10% tea tree oil in alcohol. I also made a batch with no preservative. The non-preserved GA went bad after 11 days. It went yellowish, cloudy and stank like 7 pairs of old socks kept warm in a plastic bag. To date the GA / tea tree oil solution appears a tiny bit cloudy but has no visible mould. The smell of tea tree oil is overpowering so I am unable to judge its efficacy by smell. I'm hoping soon to make some prints using the GA / tea tree solution. I would also make side-by-side comparison with non-preserved (fresh) GA solution. Elsewhere I've read that the properties of GA solution change with age (clearing, staining, etc). Noting these ageing effects and noting that I cannot judge it by smell how would I know if the solution is bad due to ageing / contamination or some other factor? Thanks, PAUL
|