Keg build: first miscue, Kastolite 30 LI/ Inswool

Discussion in 'Furnaces and their construction' started by Fasted58, Oct 27, 2018.

  1. Fasted58

    Fasted58 Silver

    Or... my Chia Pet foundry build o_O

    Long story short, I poured the lid and base of a half-keg w/ Kastolite 30 w/ 1" Inswool lining.

    Cooler weather at night was moving in on my unheated garage but I maintained 60°F air cure w/ covering for 36 hours w/ halogen work lights. Slowly raised the refractory temp (measured at surface w/ Fluke 62 Max+ IR gun) from 60-70-80 degrees by moving lights closer. Maintained 95-100° surface temp for 48 hours (90-110° recommended). Hard surface looked good.

    I abandoned finishing the keg walls and curing due to time and much colder weather for fitting the tureye and inner form. I also didn't want to final dryout w/ the propane burner in outside temps of 40° or lower.

    So, I moved the keg and lid inside the house for safe storage, floor temps are typically 65-70°. All appeared good.... until...

    Exactly seven days later this happened:

    [​IMG]

    [​IMG]

    Inswool fibers started pushing up through the Kastolite, it happened almost overnight. I scraped the surface and shop vac'd the fibers out only for them to return a few days later. There are no cracks though. I'll assume I'll have to call this compromised now.

    My best WAG is the adhesive spray I used to glue in the Inswool is gassing out and pushing the Inswool outward.

    Didn't want to TLDR but assembly is below:

    Inswool glued in w/ Clearco 444 adhesive spray, moderate application to wool and lid, tack 15-20 minutes and set in place. We have used adhesive spray in our boiler maintenance and repair w/ no adverse effects. Used a similar application of Inswool w/ adhesive for the keg base also. I rammed the inner and outer circumference where no wool w/ a 2X2, didn't ram over the wool though.

    [​IMG]

    I used an old pneumatic jitterbug sander as a table shaker to help remove entrained air. It did quite well.

    [​IMG]

    Used halogen work lights to maintain temps over cooler nights. 60° air cure and later ran up to 95-100° cure temp for 48 hours. Dryout w/ burner was not done and keg and lid was moved inside the house for the winter, my LR to be exact.

    [​IMG]

    So, my questions to y'all are:

    Has anyone experienced this before?

    Likely causes?

    Should I consider this build compromised and remove the Kastolite and wool and start over?
     
  2. PatJ

    PatJ Silver

    I have not seen that occur, but I would try using it first, since the interior of furnaces tend to get pretty gnarly looking over time anyway.

    Chances are it is just cosmetic.
    As long as the refractory stays in place and remains solid then all should be well.

    All the refractory I have seen used in furnaces has some minor cracking, but that is also generally cosmetic and can be easily patched.
    If you have major pieces scabbing off, then you have a problem, but I don't anticipate that will happen.

    You don't really lose anything by trying it as-is.

    .
     
    Fasted58 likes this.
  3. Tobho Mott

    Tobho Mott Gold Banner Member

    That is a new one on me. I haven't seen fiber blanket being glued in place before either, I guess I'll be learning a cew thjngs here thanks to your experience working on boilers.

    Jeff
     
  4. Robert

    Robert Silver

    I'm with Pat on this. I''ll bet firing it will stabilize it and it will be fine.
    Robert
     
    Fasted58 likes this.
  5. That looks like mineral crystallization to me, as if your lights combined with low humidity is drying the surface and drawing moisture and minerals in the refractory to the surface to crystallize. Is the stuff you scrape off water soluble?.
     
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  6. Fasted58

    Fasted58 Silver

    I thought crystallization at first look too. Visually, the fibers initially compared to wool though.

    Pic of the scrape:

    [​IMG]

    24 hours later, when rolled between fingers it becomes like talc. And yes, it is water soluble. You are on to something, thanks.

    Can you tell me more? Is this a bad thing?
     
    Last edited: Oct 27, 2018
  7. Well it has to be depleting the refractory of whatever that mineral is, so you'll have to stop the evaporation while the refractory cures next time. Maybe putting a layer of sandwich wrap on top of the refractory to stop the evaporation driven by the lamps. Now that you have it all cast in place just use it as is, most likely it'll be fine.

    I've only used high temperature concrete based refractory, that may be something else that relies on drying out and firing to reach full strength.
     
  8. Fasted58

    Fasted58 Silver

    Refractory was covered w/ plastic for five days after pouring and leveling (see pic above), air and temp cure to 100°. There was considerable condensation under the plastic when removed. I agree burner dry out could have prevented this but wasn't possible.

    I didn't cover the surfaces when I brought them inside the house though, maybe that was a mistake??

    I should have maybe put the lid on and kept a 60-100W light bulb inside to keep some heat on and maybe slow dry any residual moisture. Still might do that.

    Apologies for not following completely through, I compared the white scrape next to the wool and the fibers looked too similar. Wrong conclusion.

    And to think I thought my first post would have been: would there be any problem not drying out the base and lid for six months... guess I'm finding out.

    Thanks guys! Hope this ends well, will keep y'all posted.
     
    Last edited: Oct 27, 2018
  9. Rtsquirrel

    Rtsquirrel Silver

    My guess is similar... efflourescence of mineral salts out of the refractory. I see it in basement walls often, looks identical. Your description of it being like talc & water soluble matches as well.
    I'm an amateur at this foundry build thing, but mine was cured without heat, sealed & wrapped with plastic for a slow cure.
    My two cents...
     
    Fasted58 likes this.
  10. It can still dry out even when frozen solid via sublimation, it just takes longer: I have some bare ice cubes out of the tray, sitting in the freezer for the last few months. They are now half the original size but still have the cube shape and still getting smaller.
     
  11. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Kastolite 30 is an insulating castable. I've never used it and have been meaning to buy a bag. If I had it when I rebuilt my electric furnace I would have used it instead of the dense castable I had on hand. Most insulating castables have some insulating grog suspended in them that provide the insulating properties. It has an interesting composition. Nearly 5% lime is something you don't see often. All castables always say to never mix less than a full bag. This is because the constituents stratify in transit. Dry mixing solves that problem. -This and the other constituents may be a contributing factor to what you are seeing. I agree with the others though. I'd use it as is.

    Best,
    Kelly

    Kastolite 30.jpg
     
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  12. Robert

    Robert Silver

    It gonna be nice Rolling Rock furnace!
    Robert
     
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  13. Fasted58

    Fasted58 Silver

    Little back story on the keg. Found on CL after months of looking, I was first call and picked it up that day. Keg was pristine, not a scratch or ding. The seller got it for his sister's graduation party in 2002. Since, he hauled it all over the country as he relocated. I paid asking price of $80, he even met me at an exit off the interstate to save time. Super nice guy, a little dismayed that I would cut it up though.

    Keg polished up great w/ green Scotch-Brite pad followed by buffer w/ wool pad and compound. Looked too nice to cut up, would have made a great coffee table for the man cave. I took it as a sign from the foundry gods tho that this was the one.

    Think I'll name the kegger build Ol "33".
     
    Last edited: Oct 28, 2018
  14. Fasted58

    Fasted58 Silver

    I vac'd the surfaces last night, plugged the vent and drain then covered w/ plastic and weighted down. No additional heat now, just room temperature. I'll take a look in a few days.

    Should have kept covered when I brought them in, rookie mistake. All how-to's I've seen formed the base, lid and walls, then cured and dried out w/ a burner. I got caught out w/ the weather, it went from August to November weather overnight. Figured I would have needed another two weeks to finish properly, not happening now.

    The lid and base took one full bag/ 55lbs.. and that's w/ 1" of Inswool as shown above. Inswool was a last minute decision, better to have than not but initially I was planning all refractory. It's all a compromise.
     
  15. Robert

    Robert Silver

    Just curious; what's the diameter of a keg vs. a propane tank?
    Robert
     
  16. Fasted58

    Fasted58 Silver

    The OD of this keg at cut lines is about 15.5". I never considered a propane tank but I could measure. I have a steel 30 gal. grease drum in the garage also but decided on the keg instead.
     
  17. Robert

    Robert Silver

    I think propane tanks are 14"
    R
     
  18. DavidF

    DavidF Administrator Staff Member Banner Member

    12" round
     
  19. Petee716

    Petee716 Gold Banner Member

    The instructions call for it to be covered for 16-24 hours after pouring, probably to give the water time to do its job and then let it out. If the mineralization causes a problem, which it probably won't, I would think it will probably just be at the surface causing some delamination maybe. Like Mark and rtsquirrel, I've seen this on block basement walls exposed to continual moisture. I mistook it for mold and would spray it with bleach every once in awhile. Now I know why the mold wouldn't go away! Lol.
    The cold weather won't cause any harm as long as it doesn't freeze while it's still green. I poured and dried my furnace out in the barn a couple of winters ago during a warm spell (high 30's, low 40s). I set it and covered it for a day and then hung a light bulb in it for a week with a 55 gallon drum over it. Even when the temps dipped it still stayed plenty warm enough to dry it out. I had done the work of mixing, pouring, and air drying on the lid in my basement because it was light enough to just carry up and down the stairs, but I also kept all of the rest of the dry materials inside until I was ready to mix and pour the furnace bore so they would be reasonably warm.
    After its initially air dried, once you start a fire in it and then put the burner in for the final dryout, the ambient temperature will be of little consequence. So your hands are definitely not tied till spring!
    Welcome, and keep it coming!
    Pete
     
  20. Fasted58

    Fasted58 Silver

    Checked tonight, five days later, and there are no crystals or condensation. Re-covered the keg and lid refractory surfaces w/ plastic and weighted down again, will check again in a week.

    And that seemed to do the trick.

    Shoulda done that from the get go, live n learn.
     
    Last edited: Nov 1, 2018

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