[TheForge] Rigidizer application

[Michael]

Ken,
Jeff's answer is pretty close to the mark. In the first place, you don't
ordinarily want to completely rigidize, because the process lowers the
insulating ability of the ceramic blanket considerably. The only way I would
recommend a completely rigidized fiber interior is in something like a
portable farrier's forge that gets bounced a lot during constant transit. In
other words, only with a piece of equipment that will be subjected to more
than ordinary stress. In such a case some efficiency is sacrificed in order
to reduce the amount of repairs that would otherwise be needed (and to
simplify them).

Rigidizer in a tube forge configuration helps to seal the ceramic fiber
against wear and tear from high velocity superheated gases. It also creates
an inner arch of support for the fiber structure (just as the specially cut
bottom bricks in an arch do; about 1/4" to 1/2" of penetration is plenty.

If you do not add anything more for sealant, the rigidizer improves
respiratory safety a lot. However, you should add a sealant layer over the
rigidizer in order to promote all the above goals, to further toughen the
rather delicate interior, and to bounce more IR back toward your work. There
are so many refractories available that I cannot asses whether Jeff's advice
about using it as an outer layer is good or bad. None of the castable
refractories I've tried would be good for this. Instead, I would recommend
Plistix 900FR, which is available from Larry Zoeller at:
http://www.geocities.com/zoellerforge/ Larry showed me the product on some
Fiberfrax at the ABANA conference in 2004 and I was VERY IMPRESSED. The
final layer should be ITC #100 or water separated zirconia (with a touch of
clay for binder. This will do a fine job of bouncing IR, but I no longer
recommend zirconia without something like Plistix 900FR beneath it.

Mikey  

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Jeffrey Polaski
Sent: Thursday, August 31, 2006 12:10 PM
To: Sponsored by ABANA
Subject: RE: [TheForge] Rigidizer application

Well, hopefully someone has a more definitive answer, but I put in the
wool first and make sure it fits like I want it. Then I fill up a spray
bottle with colloidal silica and soak the wool by spraying it. I get all
the visible surfaces and shoot a little extra deep into nooks and
cranneys to kind of laquer it *all* down and keep fiber in place later
on. The main idea is to keep any fibers from easily floating away a few
years later as the forge cracks and degrades from use. So give I give it
a good soak, and then lather on a thick slurry of castable in the
inside.

I think putting it on once the wool is in place is easier and a little
less wasteful because you don't squeeze out excess rigidized as you fold
and stuff the ceramic wool. Also, once the rigidizer is dry it cracks
apart very easily, so putting it in place lets me be more flexible with
the construction schedule.

I also put the castable refractory on once the rigidizer is dry, but
that might not be the best way of doing it.



Jeff P.


-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Kenny O.
Sent: Thursday, August 31, 2006 11:49 AM
To: Sponsored by ABANA
Subject: [TheForge] Rigidizer application

I am not sure about the rigidizer application. I am putting two layers 
of  Kaowool  in a 5gal. lpg tank.
 
     Should both be treated?

     Sprayed or brushed?

     Does it matter if they are treated before they are put in the tank,
       assuming I don't let them get rigid?

     Can I then apply refractory to the r-dizr?


Thank you one and all
Ken O'Loughlin
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