Water to make tea should be nearly that hot. Are you sure of that number? The chart from www.borax.com says 4.71% at 20 C. We are at cross purposes here. I heated borax-water to get a saturated solution as it cooled. I heated borax-glycerol to make it dissolve faster and ran into a response that appeared to be a chemical reaction at around 250 F. Of course that is hot, but I think a roast coming out of the oven is that hot or hotter. A roast should be seared in a salted cast iron pan before being put in the oven. You want hot? Be a cook for a while.
Originally Posted by Photo Engineer