Monday, December 20, 2010

Test Fire CPLT!

That there - "CPLT" - that's kiln-speak for "complete."  The premiere firing of my kiln went off without too many hitches.  And for what hitches there were, thankfully the kiln is smarter than I, and loaded with plenty of error messages and interpretive notes in the manual.  Namely with regard to the polarized lead cables on the thermocoupler not being clearly marked and, therefore, connected perhaps slightly in reversed position.  I mean, you know there's something wrong when you turn on the kiln and the temperature display drops into the negatives.  That can't be good.

But, as mentioned before, my little kiln is much easier to negotiate with than the Millenium Falcon - no Artoo unit required at all - and it was pretty short work to look up the proper error code and correct the problem.  All in all, a delay of about 15 minutes.  Loaded the kiln up with shelves yesterday afternoon and turned it on at about 10:00 PM (10:15 for the firing that actually took) to have it ready to swith off around the time I woke up.  It's quite recommended that, even with these automatic kilns, you be present at or near the time the kiln ought to shut off, just in case.  That way, I suppose, if it happens to  not shut off automatically you can power it down before it melts a hole in your foundation, I suppose.
Empty kiln, save for furniture.  Shelves, stilts, armoirs - the usual.
Anyway, all done.  Relatively foul smokey smell lingering (normal for the first firing, as you burn the protective coating off the elements so they can oxidize properly - that's what the Skutt manual says!), but it wasn't present in the house, so that's a plus.
Above you can see a capture of the three alternating displays on the kiln post-firing.  On the left, you see "CPLT" - this lets me know that the kiln reached the programmed cone range.  The center display is showing me the current temperature inside the kiln in degrees Farenheit.  This photo came about 4 hours after the kiln shut down, so it's alread cooled off quite a bit.  It would have been more impressive, I suppose, if I'd snapped the picture first thing in the morning when it was reading closer to 1600, but it was early, I was tired, and there was snow to be shoveled.  I wondered if I should be concerned that it cooled so quickly - normally it takes a good 12 hours, if not longer, to get a kiln into the range where you could consider unloading it (under 200 degrees for sure - closer to room temp, the better).  A firing that cools too quickly can spell trouble for your glazes and lead to unwanted cracking and pitting.  But, I note that it is an empty firing, and the pots that would normally be cooling inside will normally also be contributing to the kiln temperature.  I'm willing to assume that the cooling at this rate is the result, primarily, of being an empty kiln.  But I'll be looking for some information to back up that hypothesis. 

The final display, on the right, lets me know how long the firing took - in this case reading seven hours and twenty minutes.The firing time is present to alert you to any problems that you may have encountered - if your firing was supposed to take 8 hours and actually ran for 12, you obviously are having some issues.  Similarly, if you know your firing should run 12 hours, but the kiln reads that it was completed in 6, you might have a bad thermocouple that reads the kiln hot and your pots  probably aren't finished.

So that's firing one.  Uneventful once we got off the ground, so that's good.  The next test fire will come after Christmas and will involve evenly distributed cones around the kiln to make sure that it is in fact firing accurately in all areas, and not just right on top of the heat sync.  If that goes well, firing #3 will follow as a full bisque load, and firing #4 will, optimistically, be a full glaze test load. 

As for today, I will enjoy being snowed in on my last day of gainful unemployment.  I will, most likely, be making more pots, as well as taking care of some other general studio duties.  Take care, stay warm, and try to enjoy this Monday as best you can!

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