U of S | Mailing List Archive | alt-photo-process-l | Re: Bichromate Sausages

Re: Bichromate Sausages



Ah, but sausages seem to have a strange affinity for dichromates
and I'm not sure if this should be taken as funny or rather dramatic :-)

Citing US Patent 6797015 (from http://www.freepatentsonline.com/6797015.html)

"Method for producing transparent, colored cellulose sleeves.

Abstract: Process for producing dyed, tubular food wrappings from non-woven fabric coated with regenerated cellulose, characterized in that an alkaline dye liquor containing at least one dye which has been previously converted into an alkali-soluble form by chemical reduction and which can be converted into its insoluble form by oxidation is admixed to the viscose solution used for the production of the layer of regenerated cellulose, a tubular non-woven fabric is coated with the mixture of viscose solution and dye liquor, the viscose is coagulated and regenerated to form cellulose hydrate gel and the dye distributed in the viscose is reconverted into its insoluble form by oxidation; tubular food wrappings produced by this process and their use as synthetic casings for sausages..."

Later on, the patent explains that "...After the material has been rinsed, the oxidation is carried out and the original water-insoluble dye, which adheres well to the cellulose material, is again formed from the leuco form. Examples of suitable oxidising agents are atmospheric oxygen, hydrogen peroxide, sodium perborate and potassium dichromate."

This is probably OT, but I couldn't resist...

Tom Sobota
Madrid, Spain

Liam Lawless wrote:
Just for fun, here's the passage referred to, from Vogel's 'The Chemistry of
Light and Photography in their Application to Art, Science, and Industry'
(mine is 6th, ed., 1892):


Section XII. - THE CHEMICAL ACTION OF LIGHT, AND THE PEA-SAUSAGE.*

In the campaign of 1870, the well-known pea-sausage was one of the most
important articles of food for the army, and was prepared daily by
thousands.  The fabrication of the interior portion caused little
difficulty, but the obtaining so many skins created much difficulty.  As the
supply fell short, a substitute was sought in vegetable parchment.  This
paper, which is produced by dipping blotting-paper in sulphuric acid for
about a second, then washing and drying, is distinguished by its skin-like
properties of resistance.  It is impenetrable to water, and difficult to
tear.  It is therefore used for the production of bank-notes.  It was
attempted to make sausage skins of this paper, by doubling a skin
cylindrically and pasting it together.  No glue or gum can however resist
the effect of the boiling water in which the sausage has to be cooked, and
so the artificial sausage skin fell asunder.  Dr. Jacobson solved the
problem by producing an adhesive substance, with the help of the chemical
action of light, which could resist boiling water.  He mixed the glue
intended for the sausage skin with bichromate of potash, and exposed the
glued parts to the light.  This made the glue insoluble, and now the
artificial skin endured boiling water thoroughly well.  The number of
sausage skins prepared in this way, by the chemical action of light,
amounted to many hundred thousands.


* Erbswurst.



Liam