Jump to content


Photo

red versus yellow iron oxide


  • Please log in to reply
7 replies to this topic

#1 docweathers

docweathers

    Gismo Guy

  • Members
  • PipPipPip
  • 400 posts
  • LocationSpokane Wa

Posted 07 June 2013 - 08:36 PM

I would like to substitute some red iron oxide in glaze formulas that use yellow iron oxide, because I don't have any yellow, such as Hanna's fake ash. I've looked yellow iron oxide up on Insight and various places on the web. It seems to be just a less concentrated form of iron oxide, but I don't quite believe it. Has anyone had any experience making this substitution? What has been your experience?

Larry

Lawrence Weathers

Gismo Guy

Welded Sculpture
Pottery
Spokane WA


#2 oldlady

oldlady

    single firing an electric kiln to cone 6

  • Members
  • PipPipPip
  • 887 posts
  • Locationharpers ferry west va and pinellas park fl

Posted 07 June 2013 - 11:15 PM

our guild has used the same glaze for many years. the recipe is an attempt to copy old, 19th century stoneware that was made in our area. i is made with red iron oxide and i have made it with spanish red iron oxide twice and made it with yellow iron oxide once. that was just to try out yellow. nobody saw any difference in the fired results.
"putting you down does not raise me up."

#3 docweathers

docweathers

    Gismo Guy

  • Members
  • PipPipPip
  • 400 posts
  • LocationSpokane Wa

Posted 07 June 2013 - 11:37 PM

Thanks for your insight.

What is the substitution ratio between the various Iron Oxides? The amount of Fe2O3 is quite different between them.

Thanks Larry

Larry

Lawrence Weathers

Gismo Guy

Welded Sculpture
Pottery
Spokane WA


#4 Min

Min

    Advanced Member

  • Members
  • PipPipPip
  • 465 posts
  • LocationCanada

Posted 08 June 2013 - 12:48 AM

If you are using a synthetic RIO with a Fe2O3 content of approx 95% and subbing it for YIO @ approx 88% wouldn't you just adjust your recipe accordingly? Gram for gram the yellow contains 7% less iron. I don't think the difference would be of any significance in glazes with moderate amounts of iron. My guess is that in glazes containing very large amounts of YIO you might get more pinholes from the high LOI that yellow iron has.

I use a glaze where I swapped the other way around, my base glaze has a lot of red iron in it and I spray a second iron glaze on top of it, subbing the yellow iron in the 2nd glaze makes it possible to see the 2 glazes during application.

Min

#5 OffCenter

OffCenter

    Advanced Member

  • Members
  • PipPipPip
  • 1,372 posts

Posted 08 June 2013 - 08:15 AM

I was going to post something similar to what Min posted but she said it better than I would have. That's a great idea in the second paragraph!

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#6 docweathers

docweathers

    Gismo Guy

  • Members
  • PipPipPip
  • 400 posts
  • LocationSpokane Wa

Posted 08 June 2013 - 12:42 PM

That makes good sense and I will follow your advice.

Since I had seen some recipes from very advanced potters using both red and yellow iron oxides in the same glazes, I was just worried that I was missing something.

Larry

Larry

Lawrence Weathers

Gismo Guy

Welded Sculpture
Pottery
Spokane WA


#7 neilestrick

neilestrick

    Neil Estrick

  • Members
  • PipPipPip
  • 2,593 posts
  • LocationGrayslake, IL

Posted 11 June 2013 - 03:25 PM

You'll generally find very little difference between iron oxides when used in glazes. Domestic red iron oxide may be as low as 60% iron, same with yellow. Spanish iron oxide is only about 81%. Without knowing the actual iron content, I wouldn't worry about doing any math, just use the same amount.
Neil Estrick
Kiln Repair Tech
L&L Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com

#8 docweathers

docweathers

    Gismo Guy

  • Members
  • PipPipPip
  • 400 posts
  • LocationSpokane Wa

Posted 12 June 2013 - 10:32 AM

being the compulsive type, I did the math will see what happens.

thanks for all of the guidance

Larry

Larry

Lawrence Weathers

Gismo Guy

Welded Sculpture
Pottery
Spokane WA





0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users