Any way to stop instant coffee molding?

[Leon Husock]

Is there anything I can add to my instant coffee etch bath to stop it getting moldy over time? Without compromising the etching ability, of course. I'd rather not have to mix a new batch of it once a month, though I suppose it's not the worst thing in the world.

 

[12345678910]

You could try adding vinegar to acidify it.

Or aerating it with a fish stone and air pump.

 

[J-T-K]

Freezing it into ice cubes?

 

[weo]

This probably isn't going to be helpful, but I've been using the same 1/2 gallon of coffee for the past 4 years, and no mold. For the first year, I kept it in the fridge, but since then it's just been sitting on my bench. Did you make the coffee by boiling it initially, or just added the powder to water? I boiled mine, and possibly killed any bacteria to start with?
The other thing I did was to make it very strong, 1/2 lb to 1/2 gallon water. Perhaps it's so strong that mold can't live?
Those are the only things I can think of why I haven't ever had an issue with mold.

 

[milkbaby]

I keep mine in a sealed jug in the refrigerator. Been good for a year and a half so far.

 

[Willie71]

I had mine in a sealed container on a shelf. It molded. I don’t remember if I boiled it.