Forge material question

[alarmred]

I already have a coal forge and I'm looking at possibly making a propane forge. To that end, a buddy offered me some refractory bricks. These are either 70 or 80% alumina bricks and are refractory not the super light insulating bricks. Simple question is will these alumina bricks work well for a gas forge?

From my research, it seems like they will take longer to heat up, but will hold up to the temps of a forge well enough. Any reason not to use these?

Thanks guys

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[Teppojutsu]

Depends.
From what I know ( not much )
There are 2 methods (or more I'm sure) But one method relies on thermal mass (I E heavy dense bricks).
The other relies more on efficiency through insulation.

Pros and cons with both .

The bricks will take a lot longer to get to heat which is fuel consumption
But once they get to heat they hold the heat for a longer time good or bad.
But it will be more "durable" to getting poked at with hot bits and Flux

The efficient one will come.up to heat Alot faster also cools faster (I think , don't have.mine running yet)
The obvious benefit is fuel economy but it can be damaged easier and will need relined with time .
I think most people now a days are using this type (unless doing heavy billet production or lots of forge welding)

Look up Wayne co he sells forge supplies and I'm building my forge based off his designs

 

[Matt River]

Most forges use hard bricks for the base/floor of the forge to resist flux, also very good for the hardface where flame makes initial contact inside. My first propane forge was just red subsoil clay and a big torch, worked fine for a long time.