In a sentence, the order of adjectives can follow a specific hierarchy. Typically, adjectives that describe opinion or quality come before those that describe age, color, or material. In this case, if all four adjectives were used together, the order would follow as:
- opinion/quality (if there is one)
- age (old)
- color (yellow)
- material (cotton)
So, if you are choosing between "old," "yellow," "cotton," and "towel," and assuming "towel" acts as a noun here, "old" would be the first adjective used in a descriptive phrase.
For example: "The old yellow cotton towel."