The Dyeing Of Silk

Silk is covered with a natural gum which has to be removed before the

dyeing process can begin. This is done by boiling for one hour or more

in a bath containing soap, 2 to 8 ozs. to the pound of silk according

to the amount of gum on the silk. It is then well washed, and is ready

for mordanting.



The mordants mostly used are Alum, for most of the bright colours.

Tin, for brightening some colours, and as a separate mordant for

others. Iron, for black dyeing. Chrome, for certain browns such as

catechu.



The principal Alum mordant is Acetate of Alumine, prepared as follows:

Let 3 lbs. Alum and 3 ozs. chalk be dissolved in 1 gallon of warm

water in an earthenware pan, add the chalk slowly to the Alum. Add 2

lbs. white acetate of lead, stir occasionally during 24 to 36 hours.

Let it remain 12 hours at rest. Decant and preserve the clear liquor,

being careful not to stir up the sediment. Pour 2 gallons of water on

the sediment, and stir occasionally for 12 hours. Let it rest 12

hours. Decant the clear and add to the first lot. Bottle for use. It

keeps about three weeks. Of the mordant 2 parts are diluted with 1 of

water, and the silk is well worked in this for 10 minutes, after being

wetted down. Steep for 12 hours, wring out and dry. Wet down again and

return to the Alum liquor, work for 10 minutes, steep 12 hours, dry.

When thoroughly dry, wash well in several changes of water before

dyeing. For less bright colours one mordanting may be sufficient.



The mordant is used for successive batches of silk until exhausted;

the fresher the mordant, the better for brighter colours. Silk should

be dyed as soon after it is dried as is convenient.



Another Alum mordant. Dissolve 25 per cent of Alum in hot water and

add 6 per cent carbonate of soda crystals. Fill up a jar with water

and steep silk in it over-night. It must be washed before dyeing.