Propane Forge Insulation Treatment Question

[ron2k_1]

Hi,

First post here. I'm from Belize, and I may well be it's first bladesmith aspirant in couple of months.

I bought one of these vevor forges (not promoting, just giving enough details to my post)

It comes with one 1" layer of unrigidized ceramic fiber, to which I'll add another 1" for added insulation. Here are my questions:

1. Do I rigidize each layer separately before inserting the next layer of fiber?

2. Is this product (100% pure hydrophilic fumed silica powder) still acceptable for rigidizing? I already bought it based on what I read here, but now I'm reading, also here, that it may not be good. I appreciate your input:

3. I'm also considering buying the following as a top coat (65% Zirconia, 31% Silicone, and 1% alum). My questions in regards to this coat are: Is it necessary after rigidizing? Is there a better refractory coat to apply after rigidizing?

Because I'm not buying a commercially designed rigidizer, I don't have instructions and the methods used vary a bit on this forum. I know it is mixed with water  and dye and applied with a spray bottle. Can you clarify the following as well:

1.  What is the preferred mixing ratio?

2. Is it left to air dry or do you light up the forge?

3. Do you then re-apply other coats once the first coat is dry?

 

If you have further recommendation on what to do with the forge I bought, please drop them here. I don't mind the reading and I appreciate all the help on the aspect of the forge I can get.

Thank you

Ron

Edited August 12, 2023 by Mod30
Commercial links removed

[George N. M.]

Welcome aboard from 7500' (2286 meters) in SE Wyoming.  Glad to have you.

I will defer to the gas forge gurus re your questions but under the terms of service of IFI you cannot post direct links to for profit web sites.  You can say "google X" or as depcted on Y's website but not a direct URL address.

"By hammer and hand alla rts do stand."

[Latticino]

Mix as much fumed silica in as you can.  Eventually it will cease to go into suspension.  You will also want to very thoroughly clean out your spray bottle after application, or use a disposable one as I have.  No need to oversoak the blanket, you only need to rigidize the top layer.

I know that others do coat with rigidizer in both layers, but I have never found it necessary.  As I see it, the rigidizer is only there to provide a relatively hard, relatively impervious and incompressable surface for you to place the actual castable refractory insulation against.  If you use other methods of forge construction you don't even need it (i.e. versions of the one that Frosty mentioned the other day where you cast or form you liner first, then pack insulation between it and the shell).  Add a precast front ring and you have your refractory blanket well encapsulated and ready to go.

I have always hardened my rigidizer by first air drying (sometimes assisted by an overnight session with an incandescent lightbulb) then slow firing up to where the surface becomes glassy.  A full yellow glow should achieve that handsomely.

The real key is the castable liner.  These day I like to use a 1/2" - 3/4" thickness of high alumina insulating castable material like Kastolite 30.  An inner coating of an IR reflector isn't a bad idea either.  A lot depends on what you want to use the forge for, but this is fairly bulletproof.

I was not all that familiar with the Vevor forges.  Seem OK, with burners that are knockoffs of Ransome or Hammer style.  I have a preference for the former, but each to their own.  There are certainly worse forges on the market.

[Frosty]

Remember to "butter" (wet with spritzed water) the blanket before rigidizing. Buttering is a mason's technique that causes mortars or as in this case sprayed on treatments to distribute and bond more thoroughly than to a dry surface. It makes a significant difference. Always butter the existing material before applying the next. Rigidizing, troweling in hard refractories, laying brick, hanging tiles on the wall, etc. Watch a mason laying brick, they dip bricks in a bucket of water and brush water on the wall before applying mortar. They've been buttering masonry for as long as humans been mortaring brick, rock, tile, etc.

Frosty The Lucky.

 

[ron2k_1]

Thank you guys. This is how the forge would look assembled according to the pamphlet. 

[IMAGE]

I'll do as Latticino and Frosty suggests. Please correct me if misunderstood:

1. Get the layers of fabric nice and wet

2. Coat with fumed silica solution as thick as allowed on second layer only. 

3. Get it dry for some days

4. Plaster rigidized fiber with refractory like Kastolite 30. Let it dry as per instructions 

5. If budget allows, I may use that Zirconia/Silica refractory coating on top of the Kastolite.

From the very few video reviews of the forge, it seems that all I may need to do to make it more decent is add more cushion, replace the regulator and those plastic hoses.

Thank you. I'll report back once I get something hot with it. It'll be used for forging knives and because I'm cheap and a beginner, to perform all the heat treating steps. No forge welding for now.

Ron

Edited August 14, 2023 by Mod30
Remove @name tag

[JHCC]

You're missing a step between 3 & 4: the firing stage Latticino mentions above. This is not simply to dry out the rigidizer, but to melt it onto the fibers of the insulation. This makes the blanket more rigid (hence the name) and helps keep small fiber particles from breaking off and getting into the air (and thence into your lungs).

[Latticino]

JHCC: that is an accurate interpretation of my comment.

Now that I see a photo of the specific forge you are purchasing, I see a couple of potential issues that might be worth consideration (none necessarily critical, just potential improvements):

1. Threaded pipe section in the gas connection/air inlet appears to be capable of both metering the air (with the air gate that is shown closed off in the photo), and potentially adjusting the gas orifice outlet location.  For NA burners, this orifice location is very important for final tuning of the burner.  If I am interpreting the photo correctly, it will be very difficult adjusting this location once all burners are manifolded together.  I recommend that, if this adjustment is part of the design, you tune the burner (inside the forge) piped individually so you can make the adjustment before manifolding all three burners.
2. The manifold appears to be piped with tubing that is a bit small.  Typically I like to have a manifold with a relatively larger size pipe to allow it to be a balancing plenum (in a matter of speaking).  This one looks like the flow to earlier burners will potentially affect the final ones in the string.  This can make adjusting burners for equal output difficult.
3. The 1/4 turn ball valves are not the best option for use in balancing output between burners.  This is a perfect application for gas rated needle valves.
4. Adding a layer of castable refractory will hopefully help keep the insulation ceiling up.  Otherwise I predict it will sag over time.  
5. The door system, and insulation in that area, are sub-optimal.  As I've stated before, door systems are hard to design well, but at least the "front" door should be set to close with a castable against castable seal, be oriented so in the open position the hot face  isn't pointed towards the user, and be capable of being "locked" partially open (especially for NA burners that need a minimum vent area to operate).  I am a fan of doors that either slide to one side (on some form of track system) or lift vertically (4 bar linkage or counterweight).

On 8/11/2023 at 6:20 PM, ron2k_1 said:

Belize, and I may well be it's first bladesmith aspirant in couple of months

Have you checked in with Craig Kovach from Island Forge and Fab?  His profile lists him as a bladesmith in Belize.  He may be able to help you directly...

[ron2k_1]

Thank you for the clarifications. And I have one big huge apology to make. I posted the pic of the wrong forge. I already bought it and don't want to mess with it until I have the rigidizer and coating materials at hand, hence why I'm posting pics from the marketing material included with it. 

This is definitely it.

Why I bought a three burner thing? Because I'm a knucklehead impulsive buyer and didn't read enough before clicking "add to cart".  I wonder if there is anything I can do before putting the castable refractory on the ceiling to keep it in place over time and avoid the sagging you mentioned. I have a lot of expanded metal mesh around leftover from another project and wonder I can't encase the walls and ceiling of the rigidized insulation before plastering the Kastolite... 

The air metering here seems pretty remedial and easy to manipulate (in my head at least).

And I hope the valve issue you mentioned may be fixed with this design other than the other. Sorry for wasting your time with the other pic. But, it is not all useless, as now I know in case I purchase or build another one in the future if all goes right with this one. 

2 hours ago, Latticino said:

Have you checked in with Craig Kovach from Island Forge and Fab?  His profile lists him as a bladesmith in Belize.  He may be able to help you directly...

Are these members of IFI? I'll see if I can lookup members and if you can reach them privately. I searched high and low on google, facebook etc if anyone was remotely in the hobby for networking and I can perhaps visit them for direct demonstrations. Anddddd I found no one. 

[Latticino]

Just one person as far as I know.  I found Craig with a simple Google search.  He is not on IFI as far as I know.

Forge inner dimensions work out to  approximately 918 cubic inches.  That is a very large forge, especially for a beginner.  If it were me I'd cut about 1/3 away and switch it to a (2) burner forge (and fix the front door at the same time.  0.06" walls are around 16 gauge.  I'd be very surprised if they were "pure iron", and that gauge won't last too long if exposed to forge heat, so watch the skin temperature - especially at the openings.

Forge is only rated for 1202 deg. F?  That really isn't nearly high enough.  My forge regularly exceeds 2300 deg. F and would barely be idling at 1200.  Fortunately a additional layer of 2,600 deg. F rated blanket and a 3/4" thick coating of Kastolite 30 will bring it up to snuff if the burners are adequate. 

DON'T use mesh to support the "ceiling" of the forge.  Put in new liner and rigidize with forge oriented vertically if you can.  Cast, don't trowel on, the Kastolite 30 using a removable inner form (cast a full rectangular tube, including the floor, remove fire brick.  leave openings for the burners.  remove the inner form when the refractory starts to set since it will shrink when drying).  

Burners on this forge appear to be loose copies of Mikey's linear burner.  I'll let him comment on how faithful and potential drawbacks.  

[ron2k_1]

It appears that the aspect of a forge is nearly a science on its own.  I really regret not asking questions before buying. Vevor actually has a two burner forge, same design, for about 60-70% of the cost of the three burner. 

Instead of cutting a 1/3 off it, can't I just shove a fire brick the dimensions of the casted opening of the forge through the "back". Assuming my casting is square, I should be able to cut a fire brick with the opening dimensions and shove as far in as needed. I can coat the fire brick for good reflectivity. Just a thought. 

I also have about 1.5 sheets of 1/8" (about 10 gauge) metal sheeting lying around if holes appear eventually. It appears, after buying additional blanket material, I had enough materials at home to build my own forge and avoid paying the Chinese company $250 bucks for their product. We learn as we go...

In regards to the temp, it's a Chinese product and we all know how inconsistent their printed materials are. This is also included with my forge description. Is anyone familiar with that regulator? I heard it's junk and should be replaced. I'd appreciate some feedback on that as well.

Can you expand a little more on this?

5 hours ago, Latticino said:

...the "front" door should be set to close with a castable against castable seal, be oriented so in the open position the hot face  isn't pointed towards the user..

I can change the hinge door to a system that slides to the side. I have somewhat mediocre fabrication skills. However, the forge body opening already has bent edges (for rigidity I guess), so I'm not sure I can cast on top of that. 

[Frosty]

Just put together a baffle wall that will slip inside the forge and close off one end and burner. It doesn't need to "seal" a little gap won't hurt a thing. What you really want is the temporary baffle wall's interior face to radiate heat back into the forge. Closing off any of the other 2 burner's flame will be as good as closing the far door.

No telling if the regulator is good or junk, as you say their quality control only counts on things used in China. If the tank fitting fits your propane bottle you lucked out.

Take a look at the picture you posted with the burners going and remember this picture is there to sell their forges. A picture like this advertising your burner is like Firestone advertising tires with a picture of a lady looking at 4 flat tires in a raging snow storm. 

At least the propane is plumbed okay. 

I'm sorry you got sucked into buying this "forge" but you aren't the only one to make these same mistakes starting out. I made a couple just as just differently bad forges starting out.

Frosty The Lucky.