First off, on my couple of visits to the U.S. and observing comments made by our US cousins on line, I have formed the impression that many technicians are afraid of cleaning wool. Most business models seem to be based on cleaning plastic fibres where you can usually "nuke 'em". In Europe in general and the UK in particular, wool is a lot more common and we tend to have a greater experience of cleaning the fibre on a day to day basis.
I sort of disagree with your statement as I have found that many oriental rugs, especially the tribal rugs that use vegetable dyes, can frequently release colour. However, ALL oriental rugs are extensively dye tested on all colours and foundation as well as face side, including testing for a delayed bleed. A stabilising pre-treatment with an acidic rinse/dye stabiliser is also common practice, as well as an acidic final rinse.
When a dye is released on these rugs, it is frequently excess dye. Migration typically only occurs during the final stage of drying. If the rug is being cleaned by saturation with a power washer at up to 3000psi, you don't normally stabilise the dye. You just keep on cleaning and rinsing until there is no more dye released. The colour of the rug doesn't seem to be affected.
The biggest concern for me when cleaning rugs by both rinse/extraction and saturation or submersion cleaning, is the drying. If a rug must be cleaned on site, it will always be by rinse/extraction and I will always towel dry the rug by hand a) to check for cleanliness and b) to aid drying.
Obviously, there is much to learn about the cleaning of oriental rugs and in the US you have some superb specialist trainers. I was trained by Ellen Amirkhan and Aaron Groseclose,And I have had the good fortune to meet Ruth Travis on many occasions when she has been over here with Woolsafe plus the Rug Chick herself, Lisa Wagner.
For all technicians, I would recommend that they update their knowledge and understanding of carpet cleaning by attending a Woolsafe Training Course. Even if you don't clean wool it will make you a better technician. If you intend to enter the lucrative world of rug cleaning, get training from the experts. You'll be charging premium prices so you need premium knowledge and skills. Cleaning is easy, it's the identification that's difficult but Ellen showed us an easier route through this.
Safe and happy cleaning
The JAGUAR MX-2 ETM @ cross-american.com