Indigo-carmine is also known as Saxon Blue. It has been produced from indigo and sulphuric acid since 1740.
There are 2 articles in Dutch about the problem, both from 'Indigo', 1988, Textielcommissie Musea;
Roelofs en Hofenk de Graaf, 'Een uitbloedende kleurstof.'(A bleeding dyestuff)
van Nes, 'Een methode tot het verwijderen van uitgelopen indigocarmijn in borduursels'.(A method for the removal of indigo carmine stains on embroideries.
One of the cited references is also of interest;
Duff, Sinclair, Stirling (1977), 'The fastness of some natural dyestuffs on wool', Studies in Conservation, 22, pp 170 - 176.
I have had experience with two samplers with blue/green silk yarn which ran immediately in all 3 test solutions and also water. This reaction is apparently typical for indigocarmine (the dyestuff was not positively identified). The treatment described below, from the van Nes article, was followed with success.
A sampler with unstable brown silk thread was also successfully treated in the same way.
Treatment
Tests required; usual colour fastness test plus fastness to iso-propyl alcohol.
1 Wash and rinse textile. Lay it on a blotting cloth to remove excess water. Do not blot with an overlay - this will remove dyestuff.
2 Prepare 3 trays with a shallow level of iso-propyl alcohol and set them in the fume cupboard. Use rubber gloves for handling the textile and avoid breathing the fumes.
3 Lay the textile for a few seconds in each tray.
(At first there was a dramatic outsurge of colour as the iso-propyl alcohol evacuates the water and its dissolved dyestuff from the textile. This decreased with every successive rinse bath).
4 Lay the textile face down on a blotting cloth. Allow to dry in the fume cupboard or on a vacuum table. Iso-propyl alcohol is polar enough to make pinning out worthwhile (if neceaasry to control the shape) it was found.
Risks!!
Loss of colour intensity due to loss of indigocarmine during the washing process.
Washfast dyestuffs may bleed in iso-propyl alcohol.
Iso-propyl alcohol is a hazardous solvent for humans.
J.C.Barnett, 13 March 1998