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Kast-O_Lite 97

 

In my search for a better castable refractory I declare my experiments with Greencast a bust, it's just too dense to make a good liner in a small forge like I run. My new portable forge will barely hit medium orange with both burners running at max.

I talked to the guys at EJ Bartell last week and learned a bunch. Our soft fire brick is only rated to 2,200f. no wonder it deteriorates so quickly in our forges, 2,600f isn't out of the question on a normal day.

That leads to a 3,000f+ castable refractory that is a good insulator and will withstand contact with Borax based fluxes. High alumina refractories fill the temperature and flux resistance requirements but we need an insulator. The portable's liner I'm calling a failure is just a flame face over an insulating layer. I might give it one more shot seeing as I still have a bunch and a nice pile of Kaowool for a backer. I don't have high hopes though.

THE refractory I plan on using from now on is Kast-O-Lite 97. It is a high alumina bubble refractory and kind of spendy if you just look at the price tag. At 0.03% silica we can completely disregard how fast silica degrades in contact with molten borax, it's NOT a factor.

It has a max OPERATING temp of 3,300f as a flame face containing ammonia atmospheres.

It insulates nearly as well as soft fire brick.

It is concrete hard at temp and abrasion resistant.

It weighs less than ½ as much as the Greencast. So a 55lb. bag is actually less than a high density castable by the lb.

Kast-O-Lite 97 is &295.95/55lb bag and is less than half the density of Greencast 94 which current price is $190.??/55lb. bag.  

Right there is my reasoning. It's almost as tough, just as borax resistant, insulates like light fire brick and covers 2x the area per bag for about 1/3 more money.

The link I'm including is ONLY for the data on Kast-O-Lite 97 NOT an add and I'm sure EJ Bartells is buying directly from the manufacturer. http://supplies.foundryservice.com/item/castable-refractories/insulating-castables/kaolite-3300-kast-olite-97-li

I'm bringing this to the club for two reasons: First I can't afford and can't use a whole bag. Second I'm sure there are guys in the club who'd like a high efficiency option to soft fire brick in their gas forges. I'm in for 15lbs. myself and I'm SURE Travis at EJ Bartells won't yell at us if we want to order more than one bag.

Jerry AKA Frosty The Lucky.

 

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I'm a little confused here---the density listed in the link doesn't seem to harken well for the stuff as an insulating refractory.  If you follow the link to the actual specs, the thermal conductivity doesn't seem to be much better than concrete either--a little but still in the range where it's not great--about the middle of the range for common brick.

Or maybe I'm reading the numbers wrong.

Here are thermal conductivities of some common materials http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html and a direct link to the specs http://supplies.foundryservice.com/Asset/KAST-O-LITE_97_L.pdf

But maybe I'm just thinking about this or your intended use wrong.  It does seem like great stuff in terms of structure, though.

 I'd like to know how removable it is after use---that is, is it a bear to chip out if you ever have to renew the area it was used?  I ask because I'm thinking of the hearth on my old johnson style forge and it's impending conversion to a ribbon burner mailbox-style.  Hopefully that hearth would last a lifetime but I suspect that someday I'd need to chip some out to do repairs--and if it's concrete hard, that would be good to know.

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Density is between 82-84 lb/ft3 where concrete averages around 150lb/ft3 The dense high alumina refractory I'm using right now runs around 160+ lb/ft3. Most of the density difference between Kast-O-Lite and Greencast is the vacuum in the bubbles, it can't have the same or even close thermal conductivity.

I'll admit I got lost trying to decipher the thermal conductivity charts. R value I understand even if it's a metaphorical value it's intuitively understandable. The charts I looked at either didn't mention or assumed everybody knows the greater the differential the faster the heat transfer. I have the "Engineeringtoolbox" bookmarked I wish I understood it better.

I don't know how it'd be to break out but I haven't met a hard refractory a chisel and hammer wouldn't break up.

I'm sure there are guys here who use the stuff, the Pizza Oven Forge is one I remember in particular. Fellow who bought his Kast-O-Lite in Spokane I believe.

I'm hoping to hear from guys with experience using and maintaining the stuff, it LOOKS good on paper but we all know what a corner that can paint a person into.

Frosty The Lucky.

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I haven't used this material for a forge lining, but I have used a similar construction for a glass furnace liner (1.5" high alumina refractory castable, I think it was Greencast 97, inner liner, 3" Kastolite  initial castable insulation lining and another 3" of lower temperature castable for the final layer of insulation).  The multilayer construction was a bit prone to cracking from differential thermal expansion, so for the future I'd use a thin sacrificial layer of blanket in between each layer.  Stood up for over 10 years of almost constant use though, so I'd say it was pretty good stuff.

That being said, according to the product data sheet for the Kast-O-lite 97, the thermal conductivity at a mean temperature for forging use is around 6 (BTUH x inch)/(SF x deg. F).  This means for every square foot of forge surface area a 1" thickness will allow 6 BTUH to escape per 1 degree temperature differential between the forge interior and exterior.  To put this in perspective we can do a rough calculation. 

Lets assume that you have a 2" thick Kast-O-lite insulated forge that is 10" long and 8" ID.  The mean surface area (not counting the ends - we can assume very thick doors on both sides for this effort), will be right around 2 square feet.  If the forge interior is operating at 2600 deg. F and the exterior is at 80 deg. F this gives a heat loss of around 15,120 BTUH.

As a comparison, 2600 deg rated 6 # density Kaowool blanket has a thermal conductivity in that mean temperature range of around 1.56.  The heat flux equation is proportional, so the same thickness of Kaowool will reduce the heat loss by 74% (i.e. 3,931 BTUH loss through the forge walls).

Therefore to get the same quality of insulation from the castable you would need to almost quadruple the thickness of the insulation layer.  However, while this will give you a decent lining as regards insulation quality, the thermal mass of this quantity of material will take a lot longer to heat up.  Might be a good choice for a full out production shop, but I doubt it would be satisfactory for a hobby smith.

Note that I have vastly simplified these calculations by not taking into account radiant losses, surface effects and the door losses, not to mention the significant losses included with the flue gasses.

Hope this helps.

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Frosty, haven't you studied the attachments at the Forge Supplies page on my web site?  Kast-0-Lite 30 about 1/2" thick over 1" of Inswool then a pint of Metrikote IR.  You will throw rocks at anything else.  Light weight, insolating, flux resistant.  What more do you want?  I believe it is the best of all worlds.  From the commercial sellers you have to buy 55#s.What if you only need 5# or 15#s?

Let me know if I can help you.

 

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Thanks Latticino, I think you've given me a working handle, maybe I'll be able to look at the formulae and winkle them out some. I'm more than good with simplifying the calcs, I'm not trying to decide how thick to make my space ship walls.

I've been looking for an efficient face that isn't a huge heat sink and will withstand flux.

Thanks again.

 

Uh . . . You got me flat footed Wayne. :huh:  I've skimmed your pages but didn't think of looking into your refractory recommendations and builds. What you describe is about what I had in mind, I'll have to take a look at Kast-O-Lite 30.  I already have enough 8lb. Kaowool to line my little forge a few times over and have had decent luck mixing Zircopax HT with a castable refractory to make a kiln wash.

Guys in the club and I have already spoken for a 55lb. bag of the Kast-O-Lite 97 and I think we'll be up for two by this meeting.

Does 1/2" over 1" of ceramic wool make a solid enough floor to survive new guys banging it?

Thanks.

Frosty The Lucky.

 

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Wayne,

I like your composite furnace liner construction, and it is similar to the one I'm in the process of putting in to my new gas forge (first one was a little large, go figure, but will see how it performs with a ribbon burner instead of a flame retention head).  I'm going with 2" of fiber liner with a 3/8" hard refractory skin (as that is what I have on hand just now).  But would certainly consider an AP Green product instead of the refractory.  I'm curious how hot the exterior walls of your forge with 1" blanket get when the interior is at full forge welding temperatures.  Per my calculations every inch of Kast-O-lite has about the same insulating value as 1/4" of blanket, so the 1" of blanket and 1/2" of Kast-o-lite is pretty much the same as having only 1" of blanket inside the forge (though the castable insulating refractory will certainly protect the blanket from getting damaged so easily, and if high alumina will also help against flux).

What I recall of Kast o lite, which I've used alone at 4" thickness for furnace doors (works well), is that it isn't quite as hard a surface as Greencast or Mizzou (which after setting are more on the order of 3,000# concrete  IMHO).  Since the insulating value is pretty nominal at that thickness I'd probably go for a tougher refractory like Greencast 97 (with 2" of blanket) and save the Kast-O lite for the doors.

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Frosty, I have had up to 5 teen age boys taking classes and using my forge and the only time there was any damage was when one was making a rasp asp and got it in the forge but then was trying to force it out and broke off a little corner before I caught him and explained, gently, "If you got it in easily it will come out easily!"

Latticino, no the Kast-0-Lite 30 is not as strong as Mizzou or Greancast 94 but it is plenty strong enough for casting the interior of a forge.  It is not strong enough for the Ribbon Burner though, that is why I sell them for the Ribbon Burners.  According to your insolating comments 1/2" of Kast-0-Lite and 1" of blanket would be equivalent of 1 1/2" of blanket.  I can have my forge running all day and at the end reach up and touch the outside.  Now, I don't grab it or hug it.  I credit this to the blanket and Kast-0-Lite and the Metrikote that I paint over the casting.  It reflects the heat back into the forge where it is needed.

Let me know if I can help you. 

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The Kast-O-Lite 97 appears stronger than the 30 on most counts and more expensive as well but that's okay.

I don't understand what makes it too week for a ribbon burner. I must be missing something but I don't see much need for strength in a ribbon burner, it needs to be able to handle thermal cycling and high heat but where does the strength requirement come in?

Frosty The Lucky.

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Did you fire it first? Kast-O-Lite 30 data sheets doesn't show it gaining much strength till it's fired the first time and much better after being fired over 2,000f.

I still have about 25-30lbs of a castable refractory one of the fellows in the club gave me, it's a silicate refractory and appears pretty dense but might work just fine for a ribbon burner. . . . Yeah, I've been thinking of messing with ribbon burners. I'll "follow" John''s design, you have linked before I start tinkering. I have a little intuitive problem with the statements of how much pressure the blower has to develop. It sort of screams out in the face of my normal solution to a burner needing high pressure to function. That being the output ports are too small or too few in a ribbon's case. I know a ribbon is different on a fundamental level with such a large plenum behind the ribbon and a back fire into the plenum could be . . . Ungood. :o

Already I'm using my shop forge more for curing and firing the rigidizer I picked up. Sodium silicate is a haz mat by AK standards so it's really hard to come by without spending a bunch. So to cure what's available I'm having to bring everything to around 2,000f to get it to be even reasonably durable. tomorrow I'm going to try firing it on a charcoal fire and see how it works. It's been raining off and on the last week so drying time is really extended, I have light bulbs on the pieces I'm messing with right now.

Our next meeting is the 9th. and we'll probably tally up who wants the Kast-O-Lite 97 and how much, I'll order it the next day.

EJ Bartells treats us really well on supplies they carry but doesn't carry zirconia kiln washes. I'll be handing out your info for anyone who wants to buy Plistec or Metrikote for a final wash and heck wants good info about building forges burners, supplies, etc.

I'll be posting the results of the Kast-O-Lite 97  + Zircopax  mix for a hot face once I find out how it works.

I washed the inside of the new (failed) forge with a mix of 30% sifted Greencast 94 fines + 70% Zircopax but it didn't stick to the face well at all. I'd cast the flame face using a plastic sheet drafting table cover sprayed liberally with Pledge spray wax as the bottom of the form. The flame faces came out smooth and almost slick like tile. Beautiful finish but a wash isn't going to stick. I tested the flakes by popping them into the shop forge and high yellow heat doesn't change the color let alone degrade the mix.

I just need to come up with a 70% : 30% KastOLite 97 : Zircopax mix for the inside layer of the flame face but not as an added layer. Ah, the big trick will be getting the quantities right before I add water. Calculator and finger crossing time I guess.

I've probably rambled on long enough for now I get to writing, then thinking and writing and . . . It's a vicious circle you know. ;)

Thanks for the info Wayne, as usual I'll pass along what I learn. Frosty The Lucky.

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No I didn't heat or put the burner into a forge to "set" it.  That might be the trick.  The two castables I use work well right out of the form though.  I feel that it is better to go with the tougher  stuff JIC.  It sure is disappointing to spend the time and crayons, and castable only to have it break apart.

Thanks for passing the info along.

 

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I've been looking at the "COTS Refractory Database Vendor survey" and the cold crush, and other strengths go up significantly after being heated. 220-230f is the first cure temp listed and 230f is the temperature we used to drive off hygroscopic moisture. Then strength increases quite a bit at 2,700-3,000f. for the KastOLite 97. For the 30 it falls off above 230f and doesn't start coming back till 1,500f and is still less at working temp, 3,000f.

I don't see any advantage to using the 97 over 30 they're about the same insulation but the 30 is stronger across the board and much less money. Unless shipping is different, I'll have to check EJ Bartells and see if they handle KastOLite 30 and what they get.

I'm with you, I don't want to spend a bunch of time and money on materials only to have it break on me. About the crayons, are you melting them out or wrapping them in a couple layers of wax paper and slipping them out after the burner block sets?

Swapping information back and forth is why I'm here. ;)

Frosty The Lucky.

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I've read John's article a few times I was hoping you had a short cut. I'll let you know if any of my ideas work. I don't like the idea of drilling them out, I'm thinking a couple wraps of something that won't stick to the refractory will leave enough slack for them to drop out. Of course I can't count high enough to even guess how many of my ideas don't work. :huh:

Thanks Wayne, you've been helpful since I started reading your posts back when.

Frosty The Lucky.

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When I first got interested in Ribbon Burners I cut a bunch of 3/8s diameter round rod and wrapped them with painter's tape.  The ends stuck out enough that I could grab them with vice grips and work them out.  I also used painter's tape for a release on the form.  I thought at the time that I would be making the burners and selling them and wanted to avoid buying a big box of crayons every time that I was going to cast a burner.  Again I found out that I would rather figure out the process but after making a few I wanted to move on to something else.  Same with building forges and Moe's belt grinder.  I do better at selling the supplies needed by blacksmiths and bladesmiths than building the grinders, forges, burners, knives or other items.

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I hear you there, it wasn't the miners who got rich in the gold rushes.

I don't plan on making more than a couple if I get around to it but I grew up in Dad's metal spinning shop and everything was about production so I can't look at a project without at least thinking about making it faster, easier.and cheaper.

Next time you need to cast a burner block give spray pledge furniture polish a try as a release agent. Greencast 94 doesn't stick at all, not a little bit. I learned spray wax makes good release agent working in a rubber plant in Cal. I made hot and cold air ducting for aircraft and ran out of release agent on a rush job, the plant manager just ran out for half a dozen cans of Pledge and it worked a treat. Been using it ever since.

Need to sand and paint the inside of the form but that's about it.

Frosty The Lucky.

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Frosty, believe drill them it's the way to go, the bit a dash smaller than the crayon on low speed in the cordless and then a few minutes on the BBQ  a bit of black smoke and its done.

 

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Well I'll admit my background is hot glass but I have been using and abusing refractories for well over 20 years now. I can't speak highly enough about kastoltie 30 plus. The high alumina will protect it from about anything that will contact it. It has great insulating properties the price is right and nothing else compares. 

Do follow the instructions! It is a very dry mix and water is held chemically in suspension. To much water and it decrease its strength and cause cracking. For mold release Pam cooking spray and plastic wrap works well.            Vibrate your castings either tap by hand or use a pneumatic hammer on the forms to ensure no voids. 

Preheat your cast pieces. We use large kilns with digital controls but the idea is dry it out then draw the chemicals bonded water from the casting without producing steam. 

I know you may not have that ability in your shop to preheat. At least dry out as much as possible before really cranking the heat.

Not that it needs to be said here but nothing insulates like fiber so think of kastoltie like you do mizzou and back it up. The whole thermal fly wheel is great but no reason to have all that mass when it's not needed. 

I'll add one more thing to the mix. Plastics are great for repairs. What we refer to as plastics are actually ramable clay refractories. Some of these ramables have very high alumina content and will laugh at any flux you get on it. It comes in blocks of clay that doesn't harden until fired. I have sucsesfully repaired and patched things that wouldn't be considered salvageable. 

harbison walker has a refractory guide for calculating hot and cold face for most common found refractories. Get it if you can find it. 

Thanks for having me here. My passion for working hot metal is only second to working hot glass. 

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Thank you Sky, I've been looking at charts and taking the statements and experiences about Kast-O-Lite 30 seriously. This is exactly what I've been hoping for, positive or negative, good information is a good thing. I've yet to talk to the local supplier but have come to the conclusion  Kast-O-Lite 30 is  the stuff to use. 

I've been going over the product and comparison charts and have a good handle on drying and curing processes but I'll save everybody a Looong Frosty post for now. :)

Thanks again.

Frosty The Lucky.

 

 

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I talked with Travis at EJ Bartells regarding Kast-O-Lite 30. They carry it in stock, they're out at the moment but expect more with the next regular shipment next week. They sell Kast-O-Lite 30 for $77.78 per 55lb. bag at their Anchorage outlet I believe they have an outlet in Fairbanks but the company was recently bought out by "Distribution International" so my Yahoo Fu isn't working so well right now.

Anyway, I can afford this stuff so I no longer have to sweat over my calculator and make compromises in my forge design I can just cast what I need. I'm in for a bag, AYUP a whole darned bag! :) A bag costs less than I was thinking of spending on 15lbs. of the "97" JUST enough to line one forge.

For you Anchorage guys Give them a call @ 272-2467 to make sure it's in stock, tell Travis or Patric you're with the club and just go get a bag. I'll let the Valley guys know when I make a run into town to pick my bag up and will be happy to pick some up for them. Vise versa would be nice too.

Frosty The Lucky.

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If your picking it up make sure to ask about open boxes and scrap fiber. I have accumulated more free refractories by just asking then I would have imagined. One caveat castables do go bad with age. If you do have older castable it can be renewed by adding a small amount of calcium aluminate one percent up to 3 percent. Calcium aluminate is the cement that sets the refractory. Old refractories just won't set up, this is the cure. The more aluminate added the lower the performance temperature. 

I wanted to add some info on plastics. This is one I use and it is 85% alumina. Any patch made with this will be bullet proof. You could shape a small trough with this material that can be placed in the forge for Damascus. It will not be eaten by flux and once fired is rock hard. No insulating value but this stuff is so handy. 

http://refwest.com/browseproducts/PLASTECH-85P-55--(STD).HTML

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High alumina AND phosphate bonded! Now we're talking flux resistant refractory you betcha. Shelf life is a factor for rammables so unless a person has need for a full box waste is an added cost.

Calcium Aluminate is now on the good stuff list in my mental forge liner list. It even opens up a couple avenues of experimentation for this old tinkerer guy.

Frosty The Lucky.

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  • 2 weeks later...

The Kast-O-Lite 30 is in at EJ Bartells, I just picked up a bag and the pallet is getting down to one layer.

 

They JUST moved to mid town. 640, 57th. one block off the Old Seward Hwy, between International and Dowling, across from AIH. There is a sign up but it’s kind of hidden under the trees. Blue building and best of all, only a few blocks from The Arctic Roadrunner.

Remember to tell Travis you're with the AAB.

Frosty The Lucky.

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On 7/1/2016 at 9:12 PM, WayneCoeArtistBlacksmith.c said:

Frosty, haven't you studied the attachments at the Forge Supplies page on my web site?  Kast-0-Lite 30 about 1/2" thick over 1" of Inswool then a pint of Metrikote IR.  You will throw rocks at anything else.  Light weight, insolating, flux resistant.  What more do you want?  I believe it is the best of all worlds.  From the commercial sellers you have to buy 55#s.What if you only need 5# or 15#s?

Let me know if I can help you.

 

I'm thinking about drinking the gas koolaid and this thread has been very informative. Wayne, would this kind of construction (metal shell / wool / castable / IR coat) be acceptable for the doors as well?

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