Re: This is one pissy rug. - Latex powdering
Hi Daniel - you bring up some good questions here.
What happens in rugs that are of an inferior quality is that they cut corners, one of which using inferior latex, and adding filler to the mix to extend the product.
You see this often with contemporary hooked rugs like the first one featured in this old post.
http://therugchick.com/2009/08/11/how-a-hooked-rug-can-hang-you/
It does in fact become a problem AFTER the wash, when the immersion, the moving of the rug, all loosens the powder up. If the rug has been walked on a bit, you may see the delamination problem before the cleaning - but we usually see the big crumbling after the cleaning. If you have one of these rugs you can peel away the backing material and look for crumbles (this is on the rugs with a LOOSE backing, not the heavily attached ones).
With these pieces (and they are not always CHEAP rugs - Caroline Murray hooked rugs from Vermont, which is a designer line, can be pricey depending on the piece) - we usually have to peel away the backing material, vacuum up that powder, apply a thin layer of better quality latex, and replace the material. All of that of course is billable work.
It also helps to remove that backing to help inspect for stenciling - another problem that creeps up (and wicks up) with some hooked rugs during cleaning (also addressed in that old post).
So I would bet my dollars on the powder being the latex filler. Soap residue usually sticks to the fibers, and does not flake away - unless it's Capture or some other absorbant cleaning
compound. In fact, the post I just did today on the Chinese rug with soil embedded in the base of the fibers - that is usually what shampoo residue looks like in oriental rugs cleaned improperly - and it is a beast to get out. (That thread is called Badger, Odorox, and Rugs)
http://www.mikeysboard.com/forum/viewtopic.php?f=1&t=35206
Lisa