Silk lap (giant undyed Mulberry batts) from Thailand. This Silk lap can be up to 2 kgs per giant batt and I try to split off chunks into ~6 ounce pieces if you order more than 6 ounces, I try to split of in one whole piece. Using silk lap is how throwster yarn is made and it is really fun to work with. Since it is already carded, you can dye the entire piece you have OR, dye after spinning the throwster yarn. Many people will dye it and then intercalate into art batts.
This lap comes from Thailand and was washed, bleached and carded in family owned homes or small out buildings. Unlike China where silk is processed in factories, the silk industry in Thailand and India part of a family owned cottage industry. Family members degum, wash and bleach the silk. Then it is run multiple times through cottage industry carders. These batts are ginormous sometimes weighing 6 lbs total.
Expect your silk batt section to have an occasional piece of cotton thread (just pick it out of the batt) and to be varying shades of white. Some aren’t super bright white which is good in the way that it means there hasn’t been over scouring and over bleaching which ruins the handle. No matter what shade of white, they will dye up the same i.e. capable of picking up the brightest jewel tones.