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How hard is rigid?

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After too many months of reading and planning and and and... I have finally started working on the forge. I have the first layer of ceramic wool in place (20# propane tank) and have fired it. I made my own (with fumed silica and water in a spray bottle) with food coloring (purple)(because red and blue make... ). I guess in my mind I thought rigidized would mean like it was a hardened surface... like bread becoming toast sort of thing. Is this not the case? Is sort of mushy acceptable? I roasted it for a pretty good while and most of the food coloring has disappeared. And yes, it IS firmer than when it went in. I just had a mental picture as to what it might feel like and this is not it. There are some places where the food coloring has not gone away, like the edges. But it is as firm as the rest of it, so is this okay?

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Rigidized wool is not as hard as a refractory coating. It should be stiff but can easily be poked & cut. Some coloring is OK it will disappear in time. If you are planning to put a layer of refractory like Satanite or Kast-O-Lite 30 go ahead and don't worry about it.

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It's hard to overdo rigidizing but it really only stiffens wool up some and gives it some compressive strength so a hard refractory flame face won't break up from flexing. It's other and perhaps most important job is containing ceramic fibers so they don't break loose and become a breathing hazard.

This isn't an exact thing so don't sweat getting it "right.":rolleyes: Okay?

Frosty The Lucky.

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Thanks guys. It was the fibers that I was worried about more than anything. This is why I asked. Yes I am covering it with Kast-o-Lite 30 and Plistex.
I will move ahead then. I may have to cut back the area around the burner hole as it's kind of restrictive and I want to be able to aim the burner once everything is in place and I can see my target.
I spent... more time than I wish to admit reading the Forges 101. I re-read a lot of it a couple weekends ago as I was gearing up to do this. Once I was in the process it was like all the plans went out the window as it cut differently than I thought it would and the rigidizer sprayed far easier than I thought it would... It's the difference between tv land and reality. But it's been a fun experience so far. I can't wait to use the forge. It's been a long time in coming.
Thanks Frosty and IDF&C for all the time you invest in us!!!

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So is it ok to just coat a ceramic insulation with Kast-0-Lite 30 without ridigising it first?And what is Plistix?I’m just getting started with a gas forge.I’ve been using a hand crank coal forge for awhile now (cough,cough) Lol!

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Welcome aboard... have you read this yet? READ THIS FIRST  It will help you get the best out of the forum. From a safety perspective rigidizing is best. It is used to seal the loose fibers that will become airborne which are a health hazard. Be sure and read this.https://www.iforgeiron.com/topic/53239-ceramic-wool-insulation-safety-alert/ Have you read any of the posts in the forge section? Forges 101 will answer most questions.

 

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On 11/7/2019 at 4:04 PM, Viking James said:

So is it ok to just coat a ceramic insulation with Kast-0-Lite 30 without ridigising it first?And what is Plistix?I’m just getting started with a gas forge.I’ve been using a hand crank coal forge for awhile now (cough,cough) Lol!

You can cover refractory wool with Kastolite or other hard refractory without rigidizing the blanket. But it's not optimum, you're laying a relatively thin layer of very hard inflexible material over something that can compress and flex easily. Think of it like laying a piece of glass on a wooden table and standing on it. No problem, yes? Now lay it on a piece of foam rubber and push down in the center. If you actually do this wear gloves, safety glasses and video it. I got the demo in a hard facing class but it applies in this case. 

Plistex is a "kiln wash," another high temperature refractory that's pretty chemically inactive so things like borax based fluxes don't dissolve it. Heat also conducts through it more slowly so It absorbs and holds heat and so gets hotter than Kastolite will. It then radiates the heat in all directions. Away from the flame heat is blocked by the Kastolite and later Kaowool, to the sides parallel with the surfaces it's surrounded by equally HOT Plistex. Energy ALWAYS takes the path of least resistance so the bulk of the heat absorbed by the kiln wash is radiated back into the forge chamber and your work.

In short a kiln wash is another layer of armor protecting the forge liner and in some instances it improves the forge's effectiveness.  Make sense? 

Frosty The Lucky.

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