If you’re wondering why the extra layer of ‘ticking fabric’ is recommended between the wool batting and outer upholstery fabric, the answer is two-fold:

  1. the organic cotton ticking fabric provides an added layer of protection from light. Latex foam breaks down quickly when exposed to light – especially UV light, though I’ve seen evidence that indoor fluorescent and incandescent lighting can be detrimental as well. Both the wool batting and the ticking fabric provide a measure of protection, and the two combined will help keep your latex foam soft and long-lasting.
  2. if you are using the wool batting with a woven upholstery fabric, ticking fabric is strongly recommended to prevent migration of the wool fibers through the outer fabric, resulting in unsightly pilling on the fabric surface.

You can read more in this blog post.

Note: If you are using leather or a similar non-woven, heavy upholstery, then the ticking is not necessary.