I made some progress on the fire coat as well. Both sleeves have been studded with my powder charges. I have probably put 30 or so charges on each arm. It is starting to look and feel cool.
The front of the Mamluk fire coat is padded. Since I am allergic to horse hair and hemp, I am using cotton as the padded layer, sandwiched between 2 layers of wool. Channels are 1/4″ wide. As a final layer, I am lining the coat in wool. So far I have gone through about 800 yards of black thread.
The charges are made from natural linen 5.3 oz. Each contains about 1 tsp of powder* and is attached to the garment with wire.
*Powder charges == coffee charges. Coffee doesn’t have the potential to explode. And a coarse ground bean has the same weight and feel as black powder.