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Member Since 01 Feb 2013
Offline Last Active May 19 2013 01:40 PM

Topics I've Started

How do you make color blends in glaze

11 May 2013 - 02:29 PM

Sometimes I see pieces with different color blends in glaze, it's like one color runs smoothly into another one usually in a chaotic manner. It's hard to explain, here's a picture of what I mean:
Posted Image

I have clear glaze and some color pigments. What's the process of doing this things? Do I have to stir a pigment with water, apply it to a piece and then cover with glaze? Or do I have to mix a pigment with glaze and apply it in one layer and then do the same for other colors?

I never did glazing, just learning things.

Gas kiln won't heat up above 650C/1200F

03 April 2013 - 07:45 AM

Hello! I'm a beginner potter and still learning things. I was inspired by Simon Leach to make a similar gas kiln. I decided to go for this type of kiln because I thought it's simple to build and chip. I made it in a metal drum instead of Simon's welded wire.
The inner volume is about 115L (30gal) . It's covered with the 50mm (2in) ceramic fiber inside. I used a regular burner from a hardware store and 50L propane tank with reducer that people use in households here in Ukraine. Also I inserted there a thermocouple connected to some simple multitester with TEMP. Cones seem to be very hard to find here and expensive ($1 each, 400pieces min lot)

So I loaded some ware and started my first firing. In the first hour temp climbed to 230C/446F (valve 50% open). In next 4 hours (valve 100% open) the temperature climbed to 650C/1200F and stopped. I waited for another 1.5 hour ans then gave up and turned it off. I think I need to mention that I fired outside and it was a little windy but that didn't affect the burner. The air temp was about 12C/53F. I put the gas tank in a container with hot water so it was not freezing. The outer surface of a drum was very hot. I could touch it, but not hold my hand there.

Can someone suggest why this could possibly happen? Simon says he gets 1000C/1832F in 3 hours. So I must be missing something in my setup.
Here's my guesses:
1. The kiln volume is too big for a single burner.
2. The ceramic fiber layer must be thicker.
3. The drum must be placed in some insulation. Maybe put it in a box and cover with sand (leaving the front face open of course)?
4. The gas tank pressure is not enough (thou I don't really think this could be a case).

I attach some pics.

Another question is if it's ok to refire the same ware again to get to 1000C/1832F?