nozzle forming in kaowool

[Cary Brief]

Hello All, just putting together my first forge - a Zoeller 5 gallon metal bucket forge.   got the 2 layers of 1" kaowool in place  and built a Dave Hammer burner.  haven't had time to make the tooling to flare the SS tubing for the nozzle and I remember reading (but can't find - the reason for my post) about forming the"nozzle out of the wool, and coating it with ITC 100 instead of using the SS tubing.  Am I remembering this correctly?  If so can anyone explain - I think I got it, but would love to hear what you all have to say.  Also - any suggestions for coating everything with the ITC 100 would be helpful.  i have used it on my casting furnace - so  I know how to mix it but never used it on wool.  do you coat the edge where the door closes?  I would think the non coated wool would make a nice closure BUT I think it would degrade not being coated, adding fibers to the air.   Thanks.  Cary in Miami - where it is hot enough already.

[Dogsoldat]

I'm sure Frosty or someone with far more technical knowhow on the subject will answer shortly.   From what I remember looking up info on Ron Reil burners  the flare is only needed when not in the forge.  The flare helps to create a low pressure point that supports the flame.  In the forge the reflected heat the larger volume of the forge takes care of things.   I have  a wooden plug I put in the end of my mounting pipe inside the forge and form the fire clay around that then smooth things up after the shell more or less hardens, with a little more clay where the plug was.   Anything not coated will erode.  I have a  few patches and a back door to fix up in my little forge.

 

[Frosty]

Sure, a stiffener and a little care will turn the kaowool liner into a flare. Ron put in a lot of effort to get his burner to work in a stable way outside the forge. He didn't own a torch nor want to buy one. The short tube end flare was actually a misunderstanding between us. Commercial burners are tapered the full length of the tube making for very stable flames and strong air entrainment so the prop jet is MUCH larger. If you look at the burners on commercially made forges you'll see they're typically nickle plated tapered full length from a narrow throat with a short intake flare and a choke plate. The jets are much larger than home built burners use because the flare causes a strong pressure drop as the gas travels down it's length. The low pressure also enhances fuel air mixing for a better burn.

There are a lot of opinions about burner flares but they're not flame holders even though that's what Ron used them for. Actually perhaps that's all the short tube end flares so popular are really good for. I get just as much good from a thread protector as I do from the one Jay Hays sent me a few years ago.

Anyway, the easiest way I know of to form ceramic blanket into a flare is to use butcher or parchment paper to roll a 1:12 ratio cone with the narrow end just a bit larger than the OD of the tube end. You want several turns of paper so it's reasonably stiff, stiffer than a TP tube. Wet then saturate an inch or so of the hole in the blanket with a stiffener and insert the cone to form it. Let it dry completely and remove the paper form, parchment or butcher paper rolled slick side out won't stick to the stiffener. Next dampen it and paint it with ITC-100 or equivalent kiln wash. When you fire the burner it'll cure the  stiffener and kiln wash.

Frosty The Lucky.

[Cary Brief]

thanks all - any suggestions on a stiffener?  I didn't purchase any when I bought the blanket - didn't know I needed it.   Do you use it on the entire blanket before coating with itc-100 or just on the flare hole?  again thanks for your good information

[Frosty]

A lot of guys use a stiffener on the entire forge liner. It not only makes the blanket more rigid it prevents ceramic fibers from breaking free and drifting around out air. The stuff can be very bad to breath might even cause something akin to silicosis if you breath enough.

Now I think about it the "stiffener" is probably more properly called a "rigidizer." Just describe what you want to use it for to an expert and they'll tell/sell you what you need. I know it's available online from various vendors.

We got our materials from a Seattle pottery/ceramic supply, unfortunately I don't recall the name. They flat rated our order to us and it was very reasonable.

Frosty The Lucky.

[j.w.s.]

thanks all - any suggestions on a stiffener?  I didn't purchase any when I bought the blanket - didn't know I needed it.   Do you use it on the entire blanket before coating with itc-100 or just on the flare hole?  again thanks for your good information

Kaowool rigidizer works wonderfully but don't buy too much as it has an unopened shelf life of about 6 months. also, keep in mind that it relies on firing to actually make it rigid, prior to that when dry I'd just consider it stiff. I use a spray bottle to apply it, but you can also just dip the wool in the bucket for better saturation.

J

[Cary Brief]

i cannot find anyone within driving distance wondering if anyone (might have asked this heere already - trying to get it done asap)  I have DE (diamataceous earth) that I have read can be used, also colloidal fumed silica - easy to get at any boat store.  supposedly that is what is in the rigidizers they sell - just can't get any rock solid info.  hate to put any junk on the wool - as it is not cheap!  thanks

[Frosty]

Cary: If you put your general location in the header someone on Iforge might just have a jar, can, whatever of rigidizer left over they might let you have. Unfortunately they don't know you only live 4 houses down the street.

Regardless, just buy some of the right stuff. Buy it online if you must but stop trying to reinvent the wheel. I think I already told you why I think colloidal silica is a poor choice UNLESS you're planning on blowing glass. But . . . Diatomaceous earth? More silicates?

Just but some rigidizer, the companies have chemists and many decades, maybe a few centuries of experience  testing and making the stuff.

Frosty The Lucky.

[Cary Brief]

thanks Frosty I appreciate your information  - I am not trying to reinvent the wheel - I am on a budget and having lots of DE would make it free instead of $40-$50 for a gallon

 - I am located in Miami FL.   However I did a lot of research (I am disabled and have lots of time)  and it turns out that the majority of rigidizers are simply colloidal silica.  some have additional additives most do not.  I read the MSDS sheets.  Since I do not know about these items in this particular use - why is colloidal silica a poor choice, what is wrong with the amorphous silicates?  I would really like to know- I have used similar products on my burnout furnaces - the bottles came with the furnace, never knew what the material was.

I found many people using this particular product for just this use, and they have been using it for many years.  

http://www.remet.com/range/colloidal-silica/

[MrMaelstrom]

Colloidal silica tends to work pretty well for this application. Another good option is sodium silicate, or "water glass" that I would recommend more. They will both end up functioning the same. Remet's colloidal silica binders are generally used for the investment casting industry. Many stabilizing/rigidizer mixes, to my knowledge, are actually just sodium silicate mixed with refractory powders and clay. I know the stuff I used for my last forge was exactly that. 

The issue is that most of these binders are made with a specific particle size distribution because of the industry they are made for. That actually manages to hike up the price a fair bit. It works, and it works well, but it is a little over engineered for the purpose of stabilizing the refractory blanket. In the investment casting shelling process, the colloidal silica is what actually holds the ceramic shell together. The strength of the shell can be related to the relative sizes of those particles, and usually 2 or three different slurries with different binders are applied over the course of the shelling operation. 

The colloids are actually amorphous, which means that they are technically glass. Once they get into the furnace though, and "set" they end up turning into crystoballite (quartz) crystals which is what makes that blanket (or shell) rigid. Quartz is what ends up causing silicosis (as well as the other forms of crystalline silica), and way more care should be taken when you are replacing blanket that has been stabilized with the C.S. for that reason.

The Sodium silicate is a bit different. Essentially, once you cram enough sodium oxide into a silica glass, it can be easily dissolved in water and this solution is what you will end up buying. (silicate glasses are also water soluble, but that is a different story...). You can then add more water to it to thin it down and paint/spray it on. Once all that water evaporates out, you are left with a sodium-silicate glass that STAYS glass when fired due to the amount of sodium ions still in the network. A bit safer once you go in there and start replacing blanket in your forge. it works pretty good on its own, and if you want to give it just a bit more IR reflection, you can always add some -325 mesh mullite to it. 

http://www.amazon.com/Rutland-146-Cement-Sealer-Fireplace/dp/B004YEDQOK/ref=sr_1_1?ie=UTF8&qid=1433535206&sr=8-1&keywords=sodium+silicate 

Also, way cheaper than buying a pint of ITC-100