Wovenfix is our brand name for a medium weight woven interfacing, ideal for bagmaking.
This woven interfacing is a fabric, which feels and flows like fabric and is also very strong. It also has a thread direction.
If you want to use a thin fabric for bagmaking, while the bag or pattern calls for a piece of thicker canvas-like fabric, it is best to reinforce it with woven interfacing. If you are already using a thicker material than prescribed, you can often omit this type of reinforcement. I think of thick canvasses (waxed or not), non-stretchable artificial leather, cork leather, etc.
Woven reinforcement is also appropriate to take any stretch out of the fabric. This type of reinforcement does have a thread direction.
We have Vlieseline G700 (medium-weight, both in black and white), Wovenfix (medium-heavy and unbleached beige), Wovenfix2 (medium heavy, both in black and white) and Canvasfix in stock.
We sell all our interfacing per 50cm (a little over one yard)