I was brewing a smash ale today. I have never gotten a full 19 litres from a batch (I have only done 7), because I have an 8 gallon electric kettle with a 4500 element. I fill as high as I can and am right on the heater rheostat to turn it down as the hot break rises, and up again as it falls. Today I decided to collect extra mash. I poured a litre of the mash into the kettle at 48 minutes to compensate for boil loss. I increased the heat from 50% to 60% to regain the boil. As soon as the boil returned the foam returned and fully covered the wort. I turned it down to 40%. It rose and broke just as the first. Can anyone explain why this happens? And does this mean it would be a bad idea to add the extra unboiled mash straight to the fermentor? Thanks