Gum Arabic Preservation

Hello any experts!
I would like to make my own gum arabic of which I bought 300gr. of powder like crystals ( thought they would give me chunky stuff but evidently this is the way it is sold now).
On scanning many pages on various websites I understand that the mixture needs to have a preservative/fungicide added.
I have essential oil "Tea Tree" and would like to know how many drops to add (diluted in alcohol). Listerine is also available but not the old type.
My crystals I understand 300gr to 1 litre of water is this okay?
Any light on the matter will be much appreciated and sorry if this has previously been discussed. Thanks!

what is the intended use of this.I just add a few mg to to my self-madespotting dye to match the sheen of the paper's surface.ala AA's suggestion in 'The Print.

Ralph, thanks this will be used in Gumprinting.

I would recommend sodium benzoate for presevertation. 0,5 grams of benzoate per 100gr of gum is sufficient as I have learned recently. Fomalin, mercuric chloride, thymol and formaldehyde are also used as preservatives.

There is no standard ratio of gum to water. The quality of gum varies. I have used the same gum arabic in 1+2, 1+3, 1+5 and 1+3,3. You have to find which one works best for your workflow. You might try preparing small batches of 1+2 and 1+3 see which one works better. Some people prefer working with thicker gum arabic solutions.

Herzeleid , Thanks for this information, I will make some tests to see what gives.