Microwave kiln & microwave
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- This topic has 2 replies, 2 voices, and was last updated 9 years, 11 months ago by Shawn.
- March 29, 2013 at 5:47 pm #9952ShawnParticipant
Has anyone ever ‘burned out’ a microwave oven using this type of kiln ? I have used a brand new microwave for fusing purposes only, I’ve done 64 fuses & at first the time was about 10 min for a full fuse..now its getting to be 40 min ( !!!) so I’m returning the oven & hopefully will get a replacement. I’ve been fusing mostly at 100% power. Any ideas on fusing times & power levels so I don’t burn out my next oven ?
Much ThanxApril 3, 2013 at 3:09 am #12891culletgrozerParticipant
My experience is with a large Hot Pot microwave kiln and an old 650W microwave oven at full power. I did not count the number of firings but I guess between 200 and 300 – definitely more than you have experienced. Mine is also taking longer to do its fusing and is geting worse. I also vaguely recall reading somewhere on the Internet that microwave kilns “wear out”. From this I assume our micowave kilns have reached the end of their useful lives.
I suspect the dark coating inside the microwave kiln (this bit that absorbs microwave energy and re-emits as thermal energy) deteriorates (oxidises?) over time so becomes less effective. I believe it is possible to re-coat microwave kilns but I have not tried it.
Mine has developed thermal expansion/contraction cracks so now heats up unevenly. Again a re-coating might resolve this at least temporarily.
Firing times were usually about 8-10 minutes, but now are taking longer and longer (currently about 40% longer). I couldn’t fire any faster with my 650W microwave oven but comments I’ve read on the Internet suggest that higher wattages can cause thermal shock problems with the glass.April 5, 2013 at 1:39 am #12892ShawnParticipant
Thanx for all your info. Seem that the problem was the microwave itself as the kiln worked fine in another microwave. As you mentioned, I think the wattage was also too high so the ext oven I get will bbe lower wattage.
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