Dripping iron and crusty iron oxide?

[Earthandwater]

Hi!

I enjoy decorating with iron oxide, but I have trouble making things work. I have two main issues:

I do not quite know how to dilute it: i have diluted with water, but it so easily "drips" down.  When I use less water, i find the iron oxide "warps" it sort of gets a burnt crust where it is at its thickest. I am firing at 1230C.

Should i dilute more, with more water? Or should i dilute with slip instead, to prevent it "dripping" down the ware? Any tips will be greatly apprectiated!

[Babs]

When are you applying it...greenware or onglazing?

[Earthandwater]

I usually apply to greenware, sometimes bisqueware.

 

[Min]

There is a thread here on thickening up iron oxide washes. Xanthan gum, glycerin and a few other things that people use. 

 

[Magnolia Mud Research]

Adding to the leads from Min

applying iron onto greenware:

Wait until the clay has dried at least to the leather hard stage before applying a water based iron oxide, otherwise the water in the clay will not allow the water suspending the iron oxide to be absorbed and the whole slurry of water and iron will roll down the hill to form the big puddle at the low point.  

Thickening the slurry with additives such as redart, glycerine will help but the liquid must be absorbed into the (vertical) surfaces (or evaporated) to get the iron oxide particles to adhere to the surface of ware.  

My suggestion is to make some small test pieces of clay and try various application approaches and develop your own technique for getting the amount of iron onto the clay so that you get the result you want.  
work out the details of application on pieces of scrap clay at various levels of dryness and slurry consistency before using the technique on pots that you expect to be "good".  i.e. practice on scrap then succeed on the project. 

I have used "QUIKRETE Terra Cotta Cement Color Mix" (a commercial thick water based slurry of red iron oxide used to color wet cement in a cement mixer available at your local home supply store) instead of making my own iron slurry. The iron from the diluted QUIKRETE does not settle as fast as it does from homemade slurries.  

The most controllable iron colorant I have used is Liquitex Mars Black artist acrylic paint; there are other brands that should work, but make sure that the paint is iron based not graphite.  test, Test, TEST on SCRAP!

LT

[Earthandwater]

Thank you both!

Yes, I wait until leather hard, but I still find that if I want to press a little extra in the brush stroke, suddenly it just pools down. But yes, I will test and thanks so much for your mixing tips!

On the other problem, does anyone have any input? It was a little hard to describe so I am attaching an image below:

[Min]

Iron oxide plus water when fired at midrange doesn't fuse with the body very well, especially when heavily applied like this. Try adding a bit of frit or gerstley borate to the iron so it creates a better bond with the claybody. Do some tests using between 10 and 30%. Another approach would be to use an underglaze instead of an iron wash for the brushwork.

edit: avoid high calcium frits like Ferro 3124 as the calcium will bleach out the iron.

[Earthandwater]

Thank you so much!

But, it applying it thinner a solution? I notice that everything is well at the top, where it is thinner. I had a thought after I read the other replies: can I mix a little slip into the iron/water mix? Then it will be diluted, but not so heavy.

I have tried some underglazes, but do not really like them, they are so thick and creamy. Maybe if i dilute them, but I really like the color of oxides better.

[Min]

For cone 10 the flux (frit or gerstley borate) probably isn't necessary but for low or midfire it will help, at any temperature a bit of clay will help suspend the iron oxide. Like @Magnolia Mud Research said above, test on scrap with various applications and approaches. 

[Earthandwater]

Thanks a lot!