All of them came out good and hard. I was also trying out salt glazing just to see what would happen on the bricks.
All of the ones on the bottom two layers showed the effects of the salt.
The heat must have been more intense the nearer they were to the firebox vents.
I will need to work on how I place them as they tend to sag and crack as they get that hot.
If I can perfect this they would make a very interesting and weatherproof outdoor bbq grill.
Have you tried sitting the bricks on their sides in the kiln? Rather than their bottoms? It might reduce the sagging some.
ReplyDeleteFrazer.
Hi Richard,
ReplyDeleteReally glad that Flora has managed to reach higher temperatures. You are right about some bigger kilns taking longer to wake up, and firing bricks does mean that you are having to heat up a much larger thermal mass than most potters would be doing in that size of kiln. Your blower arrangement looks a great asset to woodfiring. It's something I've occasionally thought of trying, but usually manage to get to temperature on natural draft alone. I recall that there is a 'rule of thumb' that chimneys should be 3 times the height of the chamber to provide enough "pull" to get to stoneware temperatures. You can also taper, especially near the top, to get additional draft.
I find that the packing of my kiln is very important. If I fill things too full in the chamber I can sometimes make things hard for myself due to not allowing enough room for the flames to pass through.
Anyway, you're doing great!
Peter, Yes, Ive found out the hard way that thermal mass is a huge consideration in firing. Other thing I noticed are the temperature in my kiln is much higher at the bottom near the firebox vents. I can be maybe around 1600F at the top if the ware chamber in a bright red, and glowing yellow 2000F+ near the floor vents. If im firing bricks, they need placed longwise front to back, spaced about 3/4" apart so as not to impead the flow of the flame gases. Pottery isnt as critical on the flow for me so far. It seamed that so far the salt glazing only works with the clay I am using in the hotter areas near the chamber floor areas. So Im interpereting that to be 2000F+ is needed to glaze with salt for me.
ReplyDeleteOn another note, I just won my bid on Ebay for my first pyrometer! Cant wait to get it.
Frazer, You are right. I think I will no longer place the bricks to span open gaps any more either. that should help too.
ReplyDelete