Sgrafitto Slip, need help…
Posted 03 November 2011 - 10:25 PM
Any ideas on how I might work out a solution?
Posted 04 November 2011 - 02:46 AM
Posted 04 November 2011 - 08:59 AM
This one might help with your iron burn through slightly because it contains a zirconium opacifier.
Six Corners Engobe I, cone 04
Boron Frit - 48
Soda Spar - 12
Ball Clay - 30
Zirconium Opacifier - 8
Tin - 2
This one is listed as being dry surfaced and very durable
Fair Haven Engobe, cone 04
Boron Frit - 23
Soda Spar - 42
Ball Clay - 33
titanium - 02
You might give these a test and see if they work for your process. I've found most things in this book just work. For Boron Frit it's calling for 3124 in most recipes. OM-4 ball clay. I think the last time I went they sold me uni-spar for a soda spar, but anything that will mimic Kona f-4.
Posted 07 November 2011 - 09:15 PM
Is there a particular reason for choosing an engobe for leather hard pots?
The thing though, is that I rather change slip/glazes than the way I work. I usually don’t clean or work pots until they are bone dry. Since commercial underglazes and GB glazes have worked, I thought maybe someone here might have been able to tell me the elements I need to take into account in formulating a slip that would fit (no pun intended) my current way of working.
Posted 07 November 2011 - 09:39 PM
Posted 08 November 2011 - 05:01 PM
Posted 24 March 2012 - 03:53 PM
Engobes and commercial underglazes are kind of halfway between clay and glaze- they don't fuse to the point of forming glass like a glaze, but they fuse more than clay, allowing them to adhere to bone dry or even bisque pots. If you must work on bone dry, then you'll have to go this route.
Personally, I've found I can get much cleaner, crisper edges to my sgraffito lines by making them on leather hard pots that are on the dryer side of leather hard. I would give this a try, as your pots will also be much less fragile at this stage.
You also need to be aware that there are major health issues with carving and scraping on bone dry pots. You are creating a ton of dust that is full of silica and is very bad for your lungs. Working leather hard is much, much safer, from a health standpoint.
Kiln Repair Tech
Owner, Neil Estrick Gallery, LLC