Hi Laura,(posted 9639 days ago)I'm afraid you won't find any USDA approved instructions for canning milk using any method but particularly not water bath canning. Milk is a low acid food which would be susceptible to botulism if canned at ordinary boiling water temperatures which means a pressure canner would be needed.
You won't find any USDA recommended instructions for pressure canning milk but it can be done. Use ten pounds of pressure for the same length of time as you would ordinary (not thick) soup. The problem is that your product won't come out as highly desirable. Some like it but I did not find it to be very appealing.
Sorry I couldn't be more help.
........Alan.
The Prudent Food Storage FAQ, v3.5 http://www.providenceco-op.com