Catatonic Posted May 25, 2021 Report Share Posted May 25, 2021 Hi Peeps. I have a Duncan EA-820 that I just replaced the elements on, only to have the lid begin flaking and dusting all my glaze work; the kiln also misfired. Had to shut it off after 18 hours trying to reach ^6 when it leveled off below ^04. So. Much. Fun. I am wondering if the lid could be the cause of the kiln not reaching target temperature after just replacing the elements, or whether my kiln repair guy is correct in saying the elements are not up to spec. They were custom made by a reputable pottery supply place at half the cost of Paragon Kiln Company's parts, and came as coils which needed to be stretched before installation. They were broken in with a ^04 bisque firing before attempting that glaze firing. My kiln guy has been troubleshooting and all the parts other than elements, including sitter, switches, relays and the lot were tested out as a control to eliminate the chance they might be the problem. As of last two firings, it successfully reached ^04 but no higher. I could sell it as a low fire kiln to recoup some costs in good conscience and put it toward a shiny new L&L kiln if not for that flaky lid. I saw an archived thread that dealt with the question of ceramic fiber kiln lids and floors, and the suggestion to replace them with firebrick. How could that be done? And would it even be worth the cost and labor? Would love to hear some thoughts about this. Cat Quote Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted May 25, 2021 Report Share Posted May 25, 2021 Hi @Catatonic I’m moving your post into the Equipment Use and Repair section, so it gets more visibility. I see that you’ve also started some further conversations in This thread here that involves a kiln identical to your own. Let me know if you want to continue in that other one, or move the discussion over here. Catatonic 1 Quote Link to comment Share on other sites More sharing options...
neilestrick Posted May 25, 2021 Report Share Posted May 25, 2021 A flaking lid is definitely a problem, but replacing it with a brick lid is not a cheap fix. A new lid slab plus shipping will cost $300-500 depending on the size. Or if the floor is the same material and in better condition then you can swap them. They also make products that stabilize and harden fiber that may help. Is the lid still structurally sound? Unless the lid has degraded considerably, I wouldn't think it would be the cause of the kiln not getting to temp. The other issue with flaking fiber is that you're breathing those fibers every time you move the lid, and that's not good for your lungs. You can make your own lid slab, but unless you've got some experience mortaring insulating firebrick it may not go well and you'll waste a lot of time and money. New IFB run $4-6 each. Cutting the slab to size and shape is a big mess, lots of dust. The other issue is that the hinge on the kiln is probably not made to support the weight of a brick slab, so you'll need a new hinge system, which would have to come from another brand. You'll also need an outer band for the slab. All in you probably won't save much over getting a new one. If you can find a junker kiln locally that someone is selling cheap, you can use the slab and hinge from it. Honestly, sometimes kilns just need to be tossed out. Catatonic 1 Quote Link to comment Share on other sites More sharing options...
Catatonic Posted May 25, 2021 Author Report Share Posted May 25, 2021 51 minutes ago, Callie Beller Diesel said: Hi @Catatonic I’m moving your post into the Equipment Use and Repair section, so it gets more visibility. I see that you’ve also started some further conversations in This thread here that involves a kiln identical to your own. Let me know if you want to continue in that other one, or move the discussion over here. Better to keep it here. John S won't get much help from me! Quote Link to comment Share on other sites More sharing options...
Catatonic Posted May 25, 2021 Author Report Share Posted May 25, 2021 53 minutes ago, neilestrick said: They also make products that stabilize and harden fiber that may help. Any idea where I could find this stuff? It could at least make the kiln usable for low fire or glass work. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted May 25, 2021 Report Share Posted May 25, 2021 11 hours ago, Catatonic said: Any idea where I could find this stuff? It could at least make the kiln usable for low fire or glass work. http://www.ktrefractories.com/hightemp_coating.cfmhttps://www.ceramaterials.com/fiber-glue-rigidizers/ Suggest: Search refractory coatings rigidizer.. neilestrick and Catatonic 2 Quote Link to comment Share on other sites More sharing options...
Mark C. Posted May 25, 2021 Report Share Posted May 25, 2021 (edited) this will make the surface rigid-you can spray or brush it on fiber (I spray it with a mask on) pretty cheap stuff -also called ridgizier thin coat is best https://www.axner.com/search.aspx?find=RF+458 Edited May 26, 2021 by Mark C. neilestrick, Bill Kielb and Catatonic 3 Quote Link to comment Share on other sites More sharing options...
Catatonic Posted May 25, 2021 Author Report Share Posted May 25, 2021 43 minutes ago, Mark C. said: this coat is best https://www.axner.com/sodium-silicate-liquid.aspx The notes on this say its a deflocculant for making slip; I guess the use as a rigidizer is insider knowledge! Am I supposed to use it as is, or am I supposed to mix it with water, and if so, what proportions? Same directions as stated for making slip? Quote Link to comment Share on other sites More sharing options...
Catatonic Posted May 25, 2021 Author Report Share Posted May 25, 2021 1 hour ago, Bill Kielb said: Search refractory coatings rigidizer.. Great suggestion! I immediately pulled up a lot of hits and found that Paragon makes one specifically for kilns for just under $14 a pint. This is a lifesaver--thanks! Bill Kielb 1 Quote Link to comment Share on other sites More sharing options...
Mark C. Posted May 26, 2021 Report Share Posted May 26, 2021 (edited) (I guess the use as a rigidizer is insider knowledge) My mistake this is the link sorry THIN coat is best with any product like this https://www.axner.com/search.aspx?find=RF+458 I keep a gallon on hand Edited May 26, 2021 by Mark C. Catatonic 1 Quote Link to comment Share on other sites More sharing options...
Catatonic Posted May 26, 2021 Author Report Share Posted May 26, 2021 12 hours ago, Mark C. said: I keep a gallon on hand I guess using this stuff is something I am likely to be doing as regular kiln maintenance? Do you find it necessary to use this on firebrick parts of kilns as well as the fiber parts? Just curious. Quote Link to comment Share on other sites More sharing options...
Mark C. Posted May 26, 2021 Report Share Posted May 26, 2021 (edited) No is only use it when I mix it with dry milled zircon since its collidical silica (ridgidizer) That I apply to fire boxes and fiber in the flame box area of gas kilns or as a thin top coat on fiber walls. That mix is super durable and hard and I learned about coating fiber with it from glassblowers who use it building glory holes for glass work. Those are fiber lined and need to be hard with spinning glass in them. That mix sticks to just about anything fiber,hard or soft brick when its thin-if it gets to thick it will spall off (flake off) I suggest a thin coat which will keep fiber firm and solid -best sprayed-take the lid off and lay it facing up for this-lay the loose fibers down. This process will harden the fibers-spary and let dry then fire. can you post a photo of this fiber lid? Edited May 27, 2021 by Mark C. Min 1 Quote Link to comment Share on other sites More sharing options...
Babs Posted May 27, 2021 Report Share Posted May 27, 2021 Can place a top shelf between lid and pots but doesn't stop yhe hazard re inhling the airborne fibres. Ceramic buttons wired through to out side i e. Top of lid can hold it firmly in place. Wear a mask with this lid. Quote Link to comment Share on other sites More sharing options...
Linda Jensen Posted February 17, 2023 Report Share Posted February 17, 2023 Hello! I have acquired a Duncan with the soft lid and have not fired yet but need to apply rigidizer on the top because it is flaking. I am very new to kiln operation and maintenance. I know some stuff but this is new territory. I am wondering how thin to mix- I have sodium silicate and alumina hydrate to mix in ??? Proportions and apply. I am groping in the dark here…. And the cover/lid is so flaky! I was advised to trowel it on but I don’t think troweling will work but pull off the loose flakes. So, my question is- how thin/thick and if I use a sprayer won’t it clog the innards of the sprayer? Is there a special sprayer I should use? Hudson type (2 gallon with a wand) or can I use a simple plastic garden variety household spray bottle? Thank you! Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 17, 2023 Report Share Posted February 17, 2023 (edited) 2 hours ago, Linda Jensen said: I am groping in the dark here…. And the cover/lid is so flaky! I was advised to trowel it on but I don’t think troweling will work but pull off the loose flakes. So, my question is- how thin/thick and if I use a sprayer won’t it clog the innards of the sprayer? Is there a special sprayer I should use? Hudson type (2 gallon with a wand) or can I use a simple plastic garden variety household spray bottle? I would suggest buying kiln rigidiizer and following the instructions for best application. I looked at Axner / Laguna but believe it is available many other places. Quick video here: https://youtu.be/ncGdQvYf4gY - not the greatest video actually. Like the food coloring idea though. Instructions for kaowool rigidizer here: https://www.soundingstone.com/products/kaowool-rigidizer Looks like spray, dip, roll, pour …… hundson sprayer probably a good choice. Dont forget to use your mask for sure. Edited February 17, 2023 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted February 18, 2023 Report Share Posted February 18, 2023 Why are they so flaky? Is that just part of old fiber lids or has an already bad rigidiser job coming loose? Never seemed to have an issue with my fiber lid. Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 18, 2023 Report Share Posted February 18, 2023 2 hours ago, High Bridge Pottery said: Why are they so flaky? Is that just part of old fiber lids or has an already bad rigidiser job coming loose? Never seemed to have an issue with my fiber lid. They were probably not well taken care of. They're not as durable as a brick lid, so they require some extra care. I've worked on a lot of Duncan's with the fiber lids, some were fine, some were junk. Quote Link to comment Share on other sites More sharing options...
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