Mat mi (sometimes spelt mad mee) is a fabric made with a tie-dyeing process before weaving to create a design. The technique has long been practised in Thailand, particularly in the Northeast as well as some central provinces such as Chai Nat, Uthai Thani, Suphan Buri, Kanchanaburi and Lop Buri. It is also made in the Northern provinces of Chiang Mai and Nan.
To create a design, cotton or silk yarns are made into bundles with a number of yarns appropriate for the design. They are stretched on a frame called hong mi and are tied at specific positions to block the dye, a procedure known as ob in Thai. In the past, strings made from banana trunk were used for tying, but now plastic ropes are preferred. Tying must be done tightly and carefully. Positions that are tied will not absorb the dye. Tying and dyeing can be done as many times as required by the design. Weaving must be done carefully, following the order of the reels. Weavers must also draw on their experience to adjust dyed yarns to create to a perfect design. Mat mi weaving is therefore a traditional craft that requires advanced skills.