Questão PET - Read this abstract and answer the questions. Colors to Dye for: Preparation of Natural Dyes

2 - Read this abstract and answer the questions. 
Colors to Dye for: Preparation of Natural Dyes 
J. Chem. Educ., 1999, 76 (12), p 1688A 
DOI: 10.1021/ed076p1688A 
Publication Date (Web): December 1, 1999 
Abstract 
Use of dyes can be traced to earliest history. The coloring properties of materials such as berries and bark were most likely discovered when clothing accidentally became stained with them. Dyes made from natural sources such as plants, animals, and minerals tend to produce colors that wash out easily. With most natural dyes, a mordant can be used to make the color more permanent. In the mordanting process the fiber is treated with a solution of a metal salt (usually an aluminum, chromium, copper, iron, or tin salt). Then the fiber is dyed. Metal ions from the salt form strong bonds with the fiber and also with the dye, thereby holding the dye to the fiber. […] Available at http://pubs.acs.org/doi/abs/10.1021/ed076p1688A. Accessed on July 9, 2020.

a) Which materials are natural sources of dye?
b) What can be used to make the color of natural dyes more permanent?
 
RESPOSTA:
a) Plants, animals, and minerals. 
b) With most natural dyes, a mordant can be used to make the color more permanent.

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