Darker reds, such as burgundy, can assist develop trust, whilst lighter reds and pink ties can make a more personal style statement and be connected with creativity. A pink tie has occasionally expressed "solidarity with women" in the last decade, according to Woodman. Reds represent courage, energy, and strength. The traditional white tie is made from wool or silk, but modern variations include: black-tie events; blue-tie events for those who work in the arts; green-tie events for nature lovers; purple-tie events for those who are passionate about literature or history. Black-tie events are often associated with formality and sophistication, whilst blue-tie events convey informality and creativity. Green-tie events show that one is aware of environmental issues, whilst purple-tie events indicate that one is interested in ancient history or literature. There are three main types of ties: bow, straight, and spread. The bow tie shows respect by implying that one's collar is unbuttoned, so it is appropriate for formal occasions. Bow ties are most commonly used by men in business contexts or when making an impression on others. The straight tie shows that one is comfortable in one's own skin and does not care what other people think. This type of tie is usually used by men who want to make a casual style statement and don't care about dressing formally.