anti-fungal/preservative for gum arabic solution

[timeUnit]

Are there any easy to find alternatives to Mercuric Chloride or Thymol for preserving the gum arabic solution. I think I saw a bucket of Glycerine at the local art supply store... Of maybe something from the drugstore? Chlorhexidine?

I know... I'm clutching at straws here...

Any ideas?

 

[timeUnit]

Maybe Descutan: Klorhexidinglukonat 4 g Polyoxyetylen-polyoxypropylen-kondensat Fettsyre-amidoalkyl-dimetylaminoxid Isopropanol D-glykono-lakton Renat vatten till 100 ml 1 påse resp. 1 svamp innehåller 25 ml lösning.

 

[timeUnit]

Chlorhexidin alcohol contains: Klorhexidinglukonat 5 mg, etanol 56 % w/v, sterilt vatten.

 

[CarlRadford]

I was advised to use formaldehyde which appears to work - approx 7mls per 500mls of gum!

 

[timeUnit]

Well... formaldehyde isn't really easy to obtain in Sweden.

I just found out that camphor is banned here... And thymol too, I guess. Any other ideas?

 

[Jordan]

Surprised you can't get thymol... it'd work very well, I think. It's in mouthwash (Listerine) IIRC.

 

[chrobry]

Sallicylic acid (aspirin) one pill per 100 ml solution. Works very well for me.

regards,

Jan

 

[timeUnit]

Jan,

Thank you! I'll try that today!

Jordan,

I'm learning just how controlled Sweden is when it comes to chemicals... With the banning of thymol and camphor (and I think this is very old news), how are artists able to preserve their self mixed paints? As a photographer, keeping off the main track is quite difficult and expensive.

Sweden is in many ways one of the most free societies I've been in. But with chemicals, it's like living in the DDR...

 

[Loris Medici]

Sodium Benzoate

You can also use Sodium Benzoate. I use 1g per 100g of dry gum. My gum is still in perfect condition after 8 months...

 

[timeUnit]

Great! Thanks!

I just mixed three crushed "Magnecyl" tablets in my 300 ml gum arabic solution. It seems the "fillers" in the tablets don't dissolve so well, but I'll be filtering the gum later, so hopefully it will be nice and clear tonight.

Next time I'll try Sod. Benzoate.

 

[Akki14]

I'd be surprised if you can't get formaldehyde in the form of formalin for aquarium fish treatment.

 

[timeUnit]

I checked that out and it seems difficult to find it undiluted. Formalin is sold, but only in a mixture with "malachite". I don't know if that is the mineral, or what, but I don't want it in my gum. It's green!

 

[nawagi]

Gum Arabic Preservation

A drop of Phenol or Carbolic Acid per 100 ml of solution will work (if you can get it in Sweden)

NWG

 

[Akki14]

Ah. it appears you can get formalin without the malachite green (which you're correct, it's a copper mineral) in the UK without any troubles... seems to be more commonly a koi carp treatment, the stuff mixed with malachite is what I have for my aquarium tank fish.

 

[bsilverman]

I just put it in the fridge--non toxic

 

[Photo Engineer]

I just put it in the fridge--non toxic

I'm not sure what you are referring to here, but most everything mentioned in this thread is toxic in some way or another. That is why they are gradually being banned.

PE

 

[Akki14]

I'm not sure what you are referring to here, but most everything mentioned in this thread is toxic in some way or another. That is why they are gradually being banned.

PE

I think what he meant is that gum arabic without anything in it besides water, put in a fridge, keeps fairly well without the toxic stuff

 

[Photo Engineer]

I never ever put any chemical in a food refrigerator regardless of toxicity. I guess it comes from being trained that way. I have a dedicated fridge.

PE

 

[hobbit]

i´m not sure whether formaldehyde is a good idea.. as far as i know, it is used to harden gelatine, and i,m pretty sure that it as the same effect on gum arabic, so it doesn´t seem very good to me. i have heard about people putting pills against head aches in paste used for paper maché.

 

[Jim Noel]

Glyoxal is a substitute for formalin and should work well.
The aspirin idea sounds good to me. To eliminate undissolved particles dissolve the aspirin in a minute amount of water and filter that prior to adding to gum.

 

[Dana Sullivan]

I've been adding Sodium Benzoate to all of the Gum Arabic solution that I sell, for atleast the past 6 or 7 years. I use 300g of spray-dried Acacia powder to make 1 liter, with 1 gram of Sodium Benzoate as preservative. I did a test to see how well it works, and after 2 years a un-refrigerated 500 ml bottle still looked, smelled and tasted like it was fresh. Thymol is an evil smelling substance, and Glyoxal acts as a hardener, so I stay away from them.

 

[Aurum]

Thymol is part of quite a few Pharmacopoeias. Usually used as a topical antiseptic for dental work .There are limits as its quite toxic.
You could in theory substitute Clove oil, or rosmary essential oil which is used as a preservative in some natural extracts used in "Preservative free" toiletries products.

Sodium benzoate is a good choice, but can be pH sensitive and either discolour badly or be useless if the pH is outside its comfort zone
0.1% (1g/Litre) is obviously effective as Dana proved, but this material can be used upto 5g/litre routinely if you have a buggy batch of gum powder.

The other way (Which should work for solutions that are prone to bugs (Works for dilute detergent blends, which are bug fodder)
is to adjust the pH to either below 4 with a hint of acetic acid (Stop Bath) or a touch of either sodium or potassium hydroxide to take it above pH 10

I haven't tried this with gum, so I can't guarentee it won't shock stuff out, but at least you don't have to get hold of real nasty stuff like formalin, formaldehyde donor preservatives or stinky oils

 

[Aurum]

Quick link for pH of gum arabic solution and stuff here http://www.jumbo.th.com/application.html