Barb, your quilting is stunning.
You may want to take a look at this site:http://yarntree.com/081washing.htm as a start. And perhaps call the company that produces Orvus for their thoughts. When I went to the home page for the yarn tree site I noticed a fairly active Message board so was thinking there may be some people on there with experience with this issue.
In the 70's, Bucilla was one of the main companies producing the better quality quilt kits for retailers. I believe they are now owned by Plaid Enterprises. A call to them may produce some info, as well.
I have some of the samples from those old kits that I have washed a lot in my home machine and at laundromats as they are really heavy. I've just used whatever detergent was in vogue (lol) at the time and they have been just fine. There aren't any blue markings on them. Although I don't remember them being on them originally either.I purchased them directly from Bucilla as store models. I'm not sure how good my memory is for something I purchased in the 70's ....lol!
If you haven't already started the last one perhaps you could test an area and see what works.
I believe they still make these kits so if you can get ahold of one it probably tells you what method to use to remove the markings. That simple idea just popped into my "bird brain" and may be the best solution!
Lastly, if you would like me to experiment with any ideas you come up with on the old samples I have just let me know. They've been very well used! And, have had just about any kind of human, food and pet stain on them you can imagine. We now take them to the beach for the grandkids to play on. IF they had ever looked as beautiful as yours I promise they would have received a lot more respect!