So I have a square body devil forge arriving. I have my bag of Kast-o-lite.  What I can't seem to figure out clearly is do I need an inner mold for the Kast-o-lite during dry-out to keep it against ridgidized wool or is that just for things like ribbon burners? Can I just trowel it into place and have it hold? 

As always thank you all again in advanced for sharing your wisdom.

11 minutes ago, Eventlessbox said:

Can I just trowel it into place and have it hold?

If you rigidize the ceramic fiber first.

Yes you can trowel it on but don't do the whole liner at once or the side that's on top will sag. It will stand vertically just fine but the weight makes even rigidized Kaowool sag. Of course I may not have rigidized mine well enough to carry the weight.

A flat roof isn't self supporting like the roof in a cylinder (vault).  The arch conducts the downward force smoothly to the vertical sides and so won't sag. Roman aqueducts are examples of how arches support themselves by redirecting downward force. 

Frosty The Lucky.

Ok. I was thinking of doing two adjoining sides, allowing to begin to harden while supported up on a corner( two sides forming a v) then flip and do other two. 

 

23 minutes ago, Eventlessbox said:

allowing to begin to harden

I did that and have a floor with an upwards bow because it hadn't set up enough. I gave it a good 4 hours and it still sagged, took time but it sagged. I almost busted it out the next morning when I checked. 

Floor and 3-4 walls at once, no problem. Flip it over and do the roof the next day. Hmmmm? 

Frosty The Lucky.

Sounds like a plan. Just to cover all bases; other thought was using some scrap lexan I have, release agent(read crisco), put floor and two walls. Brace walls with wood spacers then flip for roof. Would this get me a smoother surface? 

Using something as a form will make smoother surfaces and I plan on using smooth linoleum rems from a flooring shop. Greased up with Crisco or equivalent. 

Before you flip it to do the roof I highly recommend you give it a day to set up hard. Once hard it'll support itself it won't be depending on the Kaowool for support.

Of course I may not have a clear idea of what you intend.

Frosty The Lucky.

Ok. I was thinking if I flipped same day it would only be with the three sheets of lexan already in place and braced before the flip, then finish last surface and put final sheet in place. All supported. 

Just concerned about having something keep me from getting to the last side next day. With work and the tiny house and special needs kids finding time two days in a row can be a challenge.

That isn't a bad plan to do the rigidizer the same way; especieally since it can be fired wet, so no day's wait to get onto the other surfaces.

That sounds like it should work. It's just hard to visualize the same thing from text. I get it wrong so often I tend to double check.

Frosty The Lucky.

A follow up question. Any suggestions on how to Kast-o-lite the door but still get it to close. 

Looks good Eventless.  I can't wait to see the progress you make with this guy.

 

11 hours ago, Eventlessbox said:

Any suggestions on how to Kast-o-lite the door but still get it to close. 

You may want to rigidize the inside of the door and then apply  a thin layer of Matrikote or Plistex to the rigidized blanket.   You shouldn't need the armor provided by the Kastolite there, but you do want to seal the fiber blanket well.

Alright. Awsome. Was planning on ordering some plistex from Wayne so that should be great. 

When I built my forge, I put the kastolite on the door, laid down a couple of sheets of saran wrap on it, closed the door and let it set. It formed a nice seal to the forge rim and saran peeled away easy later.