dyed in the wool

Firmly established in a person's beliefs or habits; deeply ingrained in the nature of a person or thing. Examples "Smith was a dyed-in-the-wool typist and never really got used to writing on computers." "John Major was described by his opponents as a dyed-in-the-wool Conservative." Etymology From the past participle of dye in the wool. The expression comes from the fact that fabric can be dyed in a number of ways. The woven fabric may be dyed after it is complete, or the threads may be dyed before they are woven. When a color is "dyed in the wool," the wool itself is dyed before being spun into threads, so the colour is least likely to fade or change. Sources Wiktionary