Hello Marshall46 Thank you for the re write that acknowledges differences in useage I have just amended it slightly Trying to make the opening paragraph neutral Removed the citation request against the quartz feldspars nepeheline syenite as these are now included Removed the bit about computer controlled kilns not least as these formulations were in use before computers Removed the citation request against the lower fuel consumption The reason is that soft paste soft porcelains irrespective of the raw materials used be it feldspar or frits are fired to lower temperatures than hard paste hard porcelains I think in that we agree lower temperatures require less fuel Thanx