U of S | Mailing List Archive | alt-photo-process-l | Re: Gum Preservatives

Re: Gum Preservatives



On Wed, 6 Dec 2006, sam wang wrote:

There are many preservatives that can be used. Judy suggested formaldehyde. Thymol works well enough for me except when I put in too little - I wanted to put in a minimum amount. The smelly gum printed fine, maybe even better than fresh. I hope you didn't throw out your spoiled gum.
Maybe there's something about mixing your own gum arabic like killing your own wild boar or grinding your own corn, but I like to get a gallon of lithographers gum & then another gallon from the same lot if I like it... It works fine (as far as I know) and the poison is already in it.

However, as a beginner I did mix gum (Sam, did you REMEMBER that? Uh oh!) & found that one drop of 40% formaldehyde per 2 ounces of whatever the mix, kept the gum seemingly unchanged for years. But now formaldehyde is difficult to get in the US ... I had a prescription from a friendly MD. (It's used for athlete's foot, or was.)

But that $17/gallon gum from Daniel Smith is now I understand about $50/gallon (either the drought, or the prevalance of gum printing driving up the price), so it could make sense to mix yr own.

I think it was Chris marvelled at early gummists tolerating the odor of sour gum... but EVERYBODY & most places stank to high heaven in the days before laundromats, hot running water & flush toilets.... Mere gum arabic was probably drowned out.

Judy