Julie P

Thank you very much Neil. I had forgotten about the L&L and I do think we can now get it here. I'll speak to the people who are building my kiln for me as they will have to source it. It is not a big kiln, just 152litres, and will have 100mm (4 inches) of K23 insulation - significantly more than the standard 2 1/2 inches of many kilns. Also, my studio could do with a bit of heat much of the year and I do have doors and windows opening to the outdoors, so I'm not too worried about the heat gain, although time will tell.. Thanks again, wonderfully useful advice as always. Julie

Thanks Tom. I only intend to install a downdraft so just trying to get a handle on what's available.

Thanks Neil. The rest of the kiln is OK, but I am researching a new kiln and have posted a topic asking for views on 2 downdraft venting systems. This old kiln will do very well for bisque firing so I'm going to keep it going and get the lid properly refurbished. Thank you for your help, always good to have an expert view. Julie

Has anyone experience of both the Orton Ventmaster and the Skutt Envirovent 2 downdraft systems? I am in the process of researching a new kiln (in the UK) and the only downdraft venting available come from the US. Very few people seem to use them here in the UK but I see it as a much better option than alternative venting systems. My kiln will be a toploader around 152 Litres ( 5.4 cubic feet) and I fire to around cone 8 typically. I'm interested in quality over price, although they both seem to be similar in cost. Has anyone had the opportunity to compare them and has a view on their performance and/or longevity? Many thanks. Julie

I had been searching for advice on how to replace the bricks in my old (UK) Cromartie kiln lid as to get it replaced by the factory is going to cost me around $400 (USD) with shipping. It is in a very bad state and I have to place a kiln shelf over my glaze ware when firing to protect it from falling bits. Having read your advice I think the best thing is to bite the bullet and just pay the factory to do the job - probably cheaper in the long run even though it hurts. Someone suggested that I turn the slab over, ie undo the band and put the damaged side on top. To do this I would probably first cover the exposed side with ceramic fibre to keep it together. Do you think that would work or be worth the effort? Or would it all just fall apart anyway? Thank you very much

Great explanations. Shame the gravel can't vibrate itself into the backyard. I had to do the same last year. Exhausting

Love this Bill thank you so much. Julie

Thank you very much Bill, this is all great stuff. I do want to try to be deliberate in decisions about kiln programming, rather than guessing and hoping for the best. However I do appreciate that there is no such thing as precision in ceramics. Thanks again for the helpful response

Thanks Min, found the table on the Orton website. The reason I got confused is that the books I am using with the Orton tables in them don't mention this important fact. Linda Bloomfield's appendix in her glaze handbook implies that it is the pace of the total temperature rise, not just the last 100°C which would confuse a lot of beginners I think,

Thank you Min, I saw this and Dave Finkelnberg's piece on Heatwork in the CAN pamphlet on electric kilns. It was that which started me on the idea of using graphs to adjust my kiln programming. I've noow changed approach and only compare the top 100 degrees in deciding on the top temp to set my controller with a given period of soaking and am going to try our the results. Really appreciate your help

It is so good to hear about these experiences, which obviously take many years of ceramic practice. I really appreciate you giving me so much helpful information. Thanks again

Thank you very much Pres Rhodes is my bible but I will look out for Hamer. Always good to have more ceramics books to read.

Thanks Neil. That's really helpful. I'm just surprised that the heatwork before that stage doesn't impact the final result but I will keep on experimenting. Thanks again for your help.

Thank you very much, that is most helpful. It doesn't make that at all clear in many of the Orton cone tables. I particularly wanted to compensate for the cooling cycle and I take it down 260 C/hr for the first 200 degrees C. Perhaps I'll try a faster crash for the first 100 degrees. Thanks again

I have been trying to be scientific about arranging my firing schedule in a small electric kiln with a controller. I understand the concept of heatwork and use cones on all shelves in my kiln to monitor results. I soak at top temperature and fire down so want to compensate for the additional heatwork these procedures involve when I set the top temperature on my controller. I understood that this could be done by looking at the area under a graph of total heatwork, but having compared theoretical models using the Orton cone firing tables, if this is indeed the case, I must be missing something. The following example uses °C, as I am in the UK, and I am referring to the Orton theoretical temperature values. 1. In the Orton table Cone 7 is reached at 1237°C when firing at 60°C /hr, if this is a straight ramp, this would take 20.3hrs, assuming a starting room temp of 17°C ((1237-17)/60). If the x-axis is time and the y-axis temperature, the area under the graph is a triangle and can be calculated as (1237 x 20.3)/2 = 12,555 2. When firing at 150°C/hr cone 7 is reached at 1255°C. As a straight ramp this would take 8.25hrs ((1255-17)/150). Then the area under the graph is also a triangle calculated as (1255x8.25)/2 = 5179 SO, these areas which are supposed to represent total heatwork to achieve cone 7 are not the same. I am clearly missing something here. Can anyone help please. Thank you