If I remember correctly, Jim Humble says that anytime mms is used undiluted on the skin, it should be completely washed off with plenty of water WITHIN 60 SECONDS. He said it would burn the skin if it were not washed off within that time. He was very precise, even suggesting using a timer to make certain the solution does not stay on the skin longer.
Try messaging here on the forum to Marlene, who talks with Jim Humble; she may be able to get an answer as to what to do for the burns.