Sarah -

I have washed many William Morris wool carpets and wool draperies, but haven't encountered indigo bleeding.  This has been more an issue with some ethnographic textiles, but the William Morris yarns seem usually to be well rinsed - and probably washed previously.  Indigo crocking occurs easily.  I use small bits of blotter paper to absorb the testing solutions and dyes, rather than cloth, avoiding too much pressure or rubbing.  If indigo seems present, I look under the microscope and determine if the blue is from solid specks or if it appears as a watercolor-like "wash".  If it is from specks that are crocking off, then I am not concerned.  Otherwise, I test with an acidified solution about pH 4.5-5 (using acetic acid).  This pH is compatible with the nonionic surfactant.  If it continues to bleed, then it may not be possible to prevent some dye loss - but if there is very little mechanical action, then the loss won't be apparent.  If copious amounts of water are used, the dye goes to the bath and is held there.  (There is a point, of course, when the bath should be refreshed before redeposition begins to occur.)  In the wash, I use continuous flowing water instead of a bath.  I use a water vacuum - working through Reemay and screens - to extract the water at the end so there is no migration and dry it quickly with a lot of air.  The Reemay laid against the textile during drying acts as a wicking material since it is the drying surface.  This is a further protection against migration.  

I am also interested to learn the experience of others.

David

Walker Textile Conservaton

On Dec 12, 2011, at 1:12 PM, Sarah Gates wrote:

> Does anyone have experience arresting fugitive natural blue dye (woad or indigo) during wet cleaning?  We are hoping to wet-clean a very soiled William Morris wool double-weave, but initial testing suggests the dark blue is fugitive.
> 
> Thanks in advance,
> 
> --
> Sarah Gates,
> Head Conservator, Textile Conservation
> M H de Young Memorial Museum
> Fine Arts Museums of San Francisco
> 50 Hagiwara Tea Garden Drive
> San Francisco, CA 94118-4501
> Telephone: 415-750-7611
> Fax: 415-750-2678
> http://famsfconservation.wordpress.com
>