Mash 5kg Grain with 13L @ 64°c
Strike temp 77°c I normally mash at 68 and strike at 77
Mix well and remove 1/3 of the mash.
I do this with a colander to remove the grain then use a jug to add some water so that you get a thick mash to decote. In the pan the water should not be above the grain.
Leave the rest of the mash to sit at 64°c
Raise the temp of the decotion to 73°c and rest for 20 minutes
You may have to add heat ocassionaly to keep at 73°c
After the 20 minutes boil for 10 to 15 minutes.
You have to stir continusly to stop scortching.
Add the dection back to the main mash and stir. The temperature should now be 68°c
You can had part of the decoction and test the temp.
If you hit the required temp then leave the reast of the dection to cool then add to the mash.
I'm not sure if you can see the difference in the picture.
At this point continue your mash until you have full Convertion of the startches.
The grain on the left is from the cooler at 64°c and the grain on the right is the decoction grain.