Crocus Martis/spanish Red Iron Oxide? Equal?

[oldlady]

while working at the Dunedin fine arts center I got a marvelous glaze result from one test.  the recipe for the glaze calls for crocus martis.  a small amount of investigating shows that there might be a tiny difference between the very expensive crocus martis and the already-in-the-glaze-room Spanish red iron oxide.  the original recipe comes from Penland and I ordered the crocus martis from their same supplier so I could get the same results. (I hope).

 

yes, I will be doing testing after the very expensive crocus martis arrives from the supplier to see if the iron oxide does the same thing but I know there are lots of you experts who will know   WHY.

 

I do not yet have a phone or computer line at the house and cannot show the recipe today because I am at the library and out of time. 

 

any ideas??

[neilestrick]

http://mobile.ceramicartsdaily.org/wp-content/uploads/2011/03/cmtechnofileiron.pdf

[oldlady]

thank you, neil, so my spanish red iron is 83 to 88 percent pure and crocus martis is 96 to 99 percent pure.

 

 my order has arrived and next week i will mix up tests with both just to see the results.