I have these hard fire bricks with the initials F J D on them. Do you know what that means, if anything? Also, these bricks have been outdoors for years, are they still ok to use for a propane forge? Any idea what the temperture rating is on them? Many Vince
not sure what those bricks are (there are literally thousands of bricks make over the years by hundreds of companies, so I would not use them for this, contact the manufacture of the propane unit (not sure what propane forge is) and they will tell you what you need for their application.