Most jackets for men’s suits have an interlining between the outer cloth of the jacket and its inner lining. Traditionally the interlining was made from horsehair canvas which was stitched into place; more economical alternatives developed in the form of a glued interlining.
A half canvased jacket uses both techniques – a sewn-in canvas piece in the lapel and chest of the jacket, a fused interlining glued into the bottom part of the jacket. This provides the benefits of the natural shape and drape where the suit needs it the most – over the chest and the lapels. The cost savings in terms of materials and labour are reflected in the price you pay since it involves less handwork.
By comparison with fused interlinings, the half canvas jacket retains the flexibility of sewn-in canvassing in the top half of the jacket – because it is not fused, you won’t face the bubbling or ungluing issues that can happen with a fully fused interlining. This in turn increases the lifespan of the jacket.