Moisture contents at which soil has smallest plasticity is called limit. For determination purpose plastic limit is defined as the water content at which a soil will just begin to crumble when rolled in to a thread of 3mm dia.
Specification of Plastic Limit Test
The complete set consists of one each :1. Glass plate 20cm x 15cm having round ends2.
Brass or stainless steel rod 3mm dia x 150mm long3.
Flexible spatula 15 cm4. Set of 6 moisture containers5.