Laccaic acid

Laccaic acids are mainly used to dye natural fabrics (mostly silk, wool, or cotton) and food, including both drinks and solid products.

The use of lac dye can be traced back to 250 AD when it was mentioned by Claudius Aelianus, a Roman writer on a volume about natural history.

This pigment made from lac dye, Indian Lake, was listed by Winsor & Newton in their 1896 catalogue.

[11][12][13] The stick lac collected from Rain trees (mostly located in Asia) can be powdered in a mill and finely ground.

Concentrated sulfuric acid is added to the filtrate until the pigment crystals precipitate, filtered through spun silk (~0.12 mm), the filtrate is allowed to stand for 1-2 days, and then the pigment crystals are precipitated, filtered and washed 3 times by water , dried crush and sift at 60 °C, resulting in a final product with a degree of separation of ~0.8%.

After the dye washing of the wastewater from the shellac cleaning, the pH value of the solution is adjusted to 4.0-4.5 with dilute hydrochloric acid.

Studies indicate that the intermolecular interactions between LCA and fibers as well as between LCA and mordants play a key role on the adsorption and dyeability of lac dye[17][18] Lac extract produces purple colors from burgundy to deep purple.

Lac is very sensitive to pH, increasing alkalinity will turn the colors plummy purple, while acidity will give bright oranges.

Mixture of milk and lac dye - A ceremony welcoming the newly wed bride to her new home
Stick lac next to colored silk strings
A picture of Kerria lacca