Mikey98118

Kast-O-lite 30 Li is, for very good reasons, the most popular castable refractory on the market. Therefore, ALWAYS do a word search to find the best offers near you. One seller will be offering five-pounds of it for $45 while another seller offers five- pounds for $17. 78. Look before you leap, or pay sucker tax. This product is even sold at Home Depot. Kast-O-lite 30 is a light weight, semi-insulating, high-alumina refractory that is resistant to cracking from thermal stress, and use rated to 3000°F; it is suitable for use as a primary flame face layer, and be cast in two layers with a secondary outer layer mixed with one third Perlite, to increase its insulation value. What if you live somewhere that forces you to pay high taxes and ridiculous shipping fees to import the refractory? Simply choose a local high-alumina castable refractory, and add silica or alumina bubbles (little hollow spheres) to suit. One kind of spheres or the other should be available from suppliers of cement; they are used to reduce weight in cement structures. Zircar Ceramics’ Bubble Alumina (not to be confused with alumina bubbles) is an extremely low-density insulating castable refractory consisting, principally, of high-purity alumina spheres, in a high-purity alumina cement binder, which is use rated to 3317°F (1825°C). Obviously, this refractory constitutes the best possible insulation, needing only the thinnest of flame face covering over it. I would suggest Plistix 900 F for a flame facing, and also as the cement binder of alumina bubbles, if you wish to mix your own bubble alumina refractory; it is use rated to 3400°F If you must import Plistix 900 F, choose a local high-alumina refractory; these are commonly employed in glass working equipment.

This can't be overemphasized. In thirty-eight years running angle grinders, I tried using gloves just one time, and still have the scar to remember how bad an idea that was.

Kiln shelves Kiln shelves are mostly considered a topic of interest to potters, because they are normally found in electric kilns. What goes on in these kilns is that heavy loads of pottery are cured at high heats for several hours; which is why high-alumina kiln furniture, including shelves, are rated by cone numbers, rather than merely use rated by temperature. The bottom line is that these shelves are engineered for maximum resistance to slumping under loads at sustained high temperatures (up to 3000 °F)—not for insulation value, which for kiln shelves is considered counterproductive. In fact, high alumina kilns are the perennial favorites of small business users despite their simi-insulating status; not because of it. The most expensive kiln shelves are nitride bonded silicon carbide, because of their high loading capacity and low shelf weights, which are important factors in a pottery kiln. Both carbon and silicon transmit heat well, but that is a plus factor—In a pottery kiln; not in a blacksmith forge or casting furnace. Fast heat transfer, combined with a maximum use temperature of 2600 °F degrees make silicon carbide a poor choice. Mullite kiln shelves are made by fusing magnesium and silicon together; a use temperature of 2900 °F degrees compares well with high alumina shelves; it is noted for thermal shock resistance, but high alumina shelves or very good at that also. Mullite is a poor insulator, and not as strong as high alumina, but the product is an acceptable alternative to shipping costs, if high alumina isn’t locally available. Half-bricks (1” thick hard fire bricks) are only acceptable for whose who’s common sense is blinded by parsimony. High-alumina kiln shelves are seven times more insulating than clay firebricks, and far tougher under loads. A floor made of semi-insulating high alumina refractory, over ceramic fiber insulation, is an acceptable substitute for a high alumina kiln shelf, and perhaps even more advisable if you want your floor shaped; but it is nowhere near as strong as a high-alumina kiln shelf, and therefore not removable for power brushing spilled flux from. As is often the case, once you have a look at the facts, choosing between viable alternatives can be tough. You only need to leave a little extra width in slots built into a cylinder’s front exhaust opening for the kiln shelf to rest in, and it can be slide in and out over the insulation without worry. If you want to weld in your forge, choose a kiln shelf floor; if not, choose Kast-O-lite 30 for your floor. If you like spending money on fuel, choose a half-brick.

Fiber blanket needs rigidizer Even the cheapest grade ceramic fiber blanket does not melt below 3200 °F. Product temperature ratings come from the level of heat that fiber products will withstand without massive shrinkage; this should illustrate the importance of locking the individual fibers in more secure positions by rigidizing; it also demystifies the seemingly magic protection conferred by a relatively thin coat of heat reflector, such as ITC-100. Ceramic fiber products need both rigidizer and finish coatings to do well in today's gas forge; this is because better burner designs and smarter forge designs create much higher internal temperatures than were common in the past. Rigidizer is especially important, because if you want your insulation to last it must be prevented as much as possible from shrinking. On the other hand, between employing 2600 °F rated ceramic fiber insulation and rigidizer, you can toughen the secondary insulation layer in your forge or furnace enough so that it should stand up well to the heat that will leak past the high emission coating (AKA IR reflector) and thin hot-face layer (typically Kast-O-lite 30. Rigidizer also helps support thin seal coatings. There are products like Plistix touted as heat mirrors which make very nice surfaces on which to paint even more effective high-emission coatings. You do not want to use thick fiber insulation layers, which tend to ripple when placed inside of curved surfaces; instead of a single 2" thick layer of ceramic fiber, place the blanket in two 1" thick layers. Ceramic fiber blanket will easily part into thinner layers via delamination between layers. Rigidize each layer after installation, and heat cure it, before installing the next layer. Finish forming burner openings before rigidizing each layer. remember to leave them just a little oversize so that they allow the burners to be moved without suffering damage. Rigidizer is colloidal silica (just fumed silica, which suspended in water) and common everyday food coloring (to allow you to visually judge how far it has penetrated); this product is easiest to dispense by spritzing after you mix up your own. But you can always pay through the nose for it, already mixed with water, from a pottery supply. I bought my fumed silica powder through eBay and got free shipping, because its weight is negligible. Ceramic fiber products are so porous that water runs right through them, unlike solid refractory, which must be slowly dried out, and then gently heat cured to prevent damage from a buildup of steam pressure. So, ceramic fiber can be "cured as you go," which means that nothing prevents you from slowly rotating a layer of blanket on a curved surface, like a casting furnace or tube forge, spritzing the rigidizer unto each area that is laid flat by the weight of the liquid, using your burner (turned down low and constantly moving over the wet fiber), to stiffen the blanket into permanent shape, and then moving on to the next area at your convenience. After creating a smooth stiff surface inside the structure, you can install another layer over it, the same way. One of the joys about completely soaking the blanket through is that both layers will bond together. Any excess rigidizer that soaks into the first layer will run right over its fiber’s surfaces by capillary action, the same as it did the first time, causing no clumping to degrade the insulating value of the outer fiber layer. The whole process is nearly goofproof. But, it’s still possible for a complete idiot to burn himself with the escaping steam that will be created, during firing. If you turn a high-speed burner on at maximum while holding still over one spot, it is conceivable (but quite unlikely) that you could even melt a patch of fiber. What keeps Murphy’s Law from messing up your efforts? First, the fiber is partly alumina, and partly silica; the aluminum oxide pretty much prevents it from melting, while the silicon oxide content bonds beautifully to the colloidal silica in the rigidizer. Secondly, the individual fibers in the blanket are very thin, which maximizes capillary action of a liquid across their surfaces. During heat curing, the colloidal silica that has wet every bit of fiber becomes a permanent vitreous outer layer on them, which creates welded joints everywhere the fibers cross each other. This glass sheathing is permanent. More rigidizer applied over it simply adds another layer after the next heat. Glass (silicon) is heavy, yet a quart jar of foamed silica (the which forms colloidal silica in water) is so light that it is obvious that the plastic container is heavier than all its content; this is because colloidal silica particles are so small that the main ingredient in the jar is air. Their tiny size is also why the powder will melt unto the ceramic fiber surfaces, this one time, at red heat. Afterward it remains solid at yellow heat. Consequently, every layer of silica sheathing on the ceramic fiber remains so thin as to leave the insulating ability of the blanket unchanged, even after repeated applications. Note: If you do not completely dry the rigidized blanket before coating the blanket layers with sealant, it can still create a steam pressure problem, damaging the final coating. So, drill a 1/8” hole in the bottom of the equipment’s steel shell, as a pressure valve, and seep hole. You can buy colloidal silica rigidizer at some pottery supply stores, but being mostly water, it is not cheap to ship from online sources; in that case you are better off to mix your own. Commercial solutions usually contain about 1100 grams of colloidal grade silica per liter of water. A liter is just over one quart (just under 34 ounces), if you want to use a kitchen measuring cup. One easily found and economical source of colloidal grade silica is fumed silica, which can be purchased from eBay, Amazon.com, and many other suppliers. Unlike sodium silicate, this product must be fired to take a permanent set on the ceramic fibers. Never allow this or any other colloidal solution to freeze, or it will clump together, and be ruined. On the other hand, measuring amounts is not needed. Commercial solutions commonly contain thirty percent fumed silica in solution with water. If you make your solution too thick to spritz, just add water. Too weak? Add more fumed silica. Hard to determine how well it is penetrating the ceramic blanket? Add food coloring.

Maybe a stronger solvent then alcohol? Also, it would take a very small orifice to be too small for most torch tip cleaners, which are made for oxyacetylene torches (smaller holes than other fuels) On the other hand, oxy-natural gas torches, which were once common, have very large holes. These tips were still around twenty years back in my neck of the woods.

Good job covering all possibilities, Buzzkill. But answer number three gets my vote. As for the problem coming and going, that sounds pretty standard with a build up of wax and tar in the gas orifice. I predict that the burner will shut down completely a little further on. Sounds like he needs to poke a wire into the orifice, to see if a tar ball falls out. This is what torch tip cleaners, which are available from a local welding supplies store for a couple of bucks, is used for.

Flame retention nozzles Details of burner construction depend on how fast and how low pressure the flow of fuel gas and air down the mixing tube is into the flame chamber made by the nozzle; and these factors hang on the overall design of a gas burner. There are two functions of flame nozzles; the lesser (but still important) of them is to provide a low-pressure area barrier before the mixing tube; thus, providing a safety factor by reducing the ability of flame to burn-back down the tube into the burner. The greater function is, by reducing pressure in the nozzle it helps "glue" the flame in place. Expanding gases from combustion creates forward pressure, which can blow the flame away from the end of the burner, blowing it out: all there is to stop that is the counter pressure of ambient air beyond the flame envelope (AKA pressure front). What air pressure? Only the difference between surrounding air and the lowered pressure of a partial vacuum formed by the drop in mixture pressure, which is made by the increased internal diameter in the nozzle area; this is assisted by the partial vacuum formed by a vortex in newer burner designs. There is an additional factor gained by flame nozzles; the ability to partially "suck" the flame back into the nozzle area, super-heating the nozzle into incandescent temperature; creating a large second ignition surface to add to the flame front that ignition usually tends to burn back toward the flame retention nozzle from. Finally, there is a synergistic motor affect created through the ability of flame nozzles to allow combustion rates to be greatly increased. Just as we are aware that the gas stream at the burners other end entrains air into the mixing tube by induction (Bernoulli's Principle), the flame itself can become, in effect, a second induction motor, speeding up mixture flow even more within the burner. But the flame also becomes a powerful induction motor on the outside of the burner, causing a lot of secondary air flow passed an entrance way, which should therefore be partially or fully closed (depending on burner design), to stop or slow secondary air, as needed. Intense burners require slide-over stepped flame retention nozzles (AKA flame retention cups); the simplest of these consist of a spacer ring, and outer tube, held in place by one to six socket set screws. The main job of the spacer ring is to keep the nozzle’s outer tube centered and parallel to the mixing tube. But, why stepped instead of tapered nozzles? Unless you have a metal spinning lathe, changes in taper angles, which are needed for changes in mixture flow is going to somewhat arduous to manage correctly; therefor, they will not be. The pitiful examples of tapered nozzles on commercial burners, prove this point. Exchanging wall thicknesses on pipe and tubing a few thousandths of an inch, to accommodate flow changes in burner designs is much esier. Cutting a longitudinal slit in the pipe or tubing being employed as a spacer tube, allows its diameter to shrink or expand as needed, within the flame retention nozzle’s outer tube, which increases the choices of suitable pipe and tube; it also allows the spacer ring to be contracted around thin wall mixing tubes, which would otherwise be dimpled by direct contact with set screws; this increases choice in usable parts, as most sausage stuffing tubes have thin wall tubing. Note: It has been repeatedly proven that an air gap between the outer tube and the spacer ring, or between the ring and the burner’s mixing tube (of up to 1/16”) does no harm, if you are willing and able to use six set screws to center the outer tube, and keep it parallel to the mixing tube. Due to the ridiculously high cost of small orders in stainless-steel pipe and tubing, as their sizes increase beyond 3/4”, mild steel pipe nipples, should be substituted for stainless-steel to make mixing tubes and spacer rings in the larger burner sizes. Schedule #40 pipe nipples of various lengths are available in hardware stores, and longer length pipe nipples are available in plumbing supply stores. Because cutting fees make 1” long parts used as as spacer rings, and approximately 2” to 4” long parts used for the flame retention nozzle’s outer tube nearly as expensive as 12” lengths), they should be cut from male pipe nipples (mild steel for spacer rings, and stainless-steel for outer tubes) to become far less expensive versions of flame retention nozzles; this can drastically reduce the costs to build your burner. This choice will produce slide-over step nozzles, which work every bit as well as nozzles that are built from lengths of tube and pipe, but which will not last quite as long, because the nozzle’s outer tube can only be made of #304 stainless, instead of #316. Note: These nozzles are kept in position with stainless steel socket-head screws. Do not use mild steel screws; they will freeze in place after a few heats. It takes months to wear out a flame retention nozzle, but they are disposable parts, and frozen screws must be drilled out. The outer tube should overhang the mixing tube by 0.125” longer than its inside diameter. The spacer ring should be 1” long, so that additional inch is added to the length of the outer tube. The nozzle is kept in position on the burner’s mixing tube with as little as a single screw, or as many as six screws, depending on how well it fits up to the mixing tube. Caution: Stainless steel flame retention nozzles on a good burner design, will get to yellow heat in ambient air, if you burn propylene, and will quickly melt down in a forge. The same nozzle will get to orange heat in ambient air, burning propane, and will melt down in a forge, if they are not recessed at least one-inch into the burner portal; do not position them close to the forge’s swirling super-heated atmosphere!

Merry Christmas, all.

Investment casting ceramic slurry If you don’t wish to pay for a large bag of investment slurry to coat ceramic blanket with, you can make up your own formula, which is good for up to eight layers; it consists of colloidal silica, which becomes a liquid binder for the dry particles in the slurry, and then acts as a fluxing agent at high temperatures, aiding the silica powder to bind together); 200 to 350 mesh fused silica powder (which is a non-reactive and thermal shock resistant filler); mix bentonite clay into the fused silica, before mixing it into the colloidal silica, to help keep the fused silica from settling out of solution; zircon flour (zirconium silicate). Slurry mixture component ranges by volume are: up to 24% colloidal silica (30 to 40% fumed silica in solution with water, by weight); between 13 and 35% 200 to 350 mesh fused silica powder; between 15 and 35% Zircon flour; up 17% bentonite clay. When used for investment casting, other components, such as silicon carbide, latex, and corn starch may be added; but are not deemed necessary for use in a refractory coating. Heat-cure the coatings at orange incandescence; 1832 °F (1000 °C).

One of the problems that remain with all this equipment is the delicacy of their speed control circuits; if you do not want them to burn out, do not run the motor slower than half speed. Aft this circuit dies, because you ignored this warning, you can bring the dead tool back to life, by cutting out the speed circuit, and replacing it with a length of wire. Your tool will only run at full speed thereafter, but that beats a dead tool.

From mini 12V angle grinders to rotary tools About three years back, Milwaukee came out with a 3" battery powered angle grinder, which they had built in China; it was a ridiculously overpriced and glitch filled design--since then the design as been improved, and it is only seriously overpriced. In the meantime, other China OEMs redesigned their own versions of that tool, which are marketed for around $50. Their tools feature 12V interchangeable batteries and high torque brushless motors. The main point of these tools isn't grinding, but surface cutting. I have wondered every since then, when the Chinese would make the obvious move, and come out with the same combination in a rotary tool, so that a battery powered rotary would finally be practical. There are now such rotary tools advertised on Amazon.com, by three different manufacturers; none of them feature a brushless motor, yet. But this upgrade is only a question of time; in the meantime swapping out the motor is just an additional twenty bucks and some wiring work

The two-brick forge The two-brick forge is merely chiseled out of 2600 °F or higher rated insulating firebricks; since the bricks are wider than they are tall, carving out two halves of a cylindrical shape is ill conceived; it is just as easy to carve two halves of an oval into the bricks; creating a larger chamber to work in. It is also best to leave one end of the hollowed-out longitudinal tunnel closed. Drill the hole for your burner two-thirds of the way toward the forge’s closed end, and slanting upward a little bit, to encourage the hot gases to swirl its way toward the forge’s open end. The hole should be about 1/8” larger diameter than the burner’s flame retention nozzle, to keep the nozzle’s expansion from cracking the brick, during heating cycles, and to provide a little secondary air, which propane torch-heads burners need to complete combustion in the forge. Seal the brick’s internal surfaces with Plistix 900, so that they will last much longer, and the forge will get hotter. The torch-head should be of the dual-fuel type, even though burning polypropylene fuel gas (wich is still misnamed MAP gas), in such a small forge will quickly destroy the brick. Nevertheless, dual-fuel torch-heads mostly use stainless-steel flame retention nozzles; this is what you need. The flame retention nozzle must be tightly encased in a stainless steel tube or pipe, to slow high-heat oxidation losses, and to keep something remaining for use as flame retention nozzle, once two-thirds of the original thin flame retention nozzle vanishes out the forge’s exhaust opening; it will happen. Brick pile forges Box shaped forges are the logical choice, when you use Morgan K 26 insulating firebricks from Thermal Ceramics, or ceramic board insulation in a forge. If you employ re-mission coated, 2700 °F rated hard ceramic board as the flame face material, with ceramic fiber blanket for secondary insulation, then a sheet metal shell is needed. If you choose 2600 °F insulating firebricks, nothing more than four threaded rods, five pieces of steel angle stock, and a threaded “U” bolt (to hold a burner) are needed, to trap “brick pile” forges together, or furnace cement, Plstix 900, etc. to glue the bricks together for a mini-forge. Threaded rod, and metal angles can be used to create box shaped forges of any desired size. Once, you feel confident that the size and shape is satisfactory, both the forge floor and top can be permanently stuck together with refractory cement. The side wall bricks should be left loose, but trapped, so that your forge remains variable in height. Mount the burner’s facing holes in one side wall, facing across to the other wall, and aimed slightly upward; they can be attached to vertical angles, which are in turn attached to horizontal threaded rods running between the top and bottom angles that keep the bricks in the forge walls trapped together. Threaded “U” bolts are the simple way to hold burners in position on the vertical angles.

It should not need pointing out that you can mix and match detail about all three forge sizes with any of the others.

Fine tuning the forge or furnace: Fine-tuning burner performance completely is usually done while running it in its intended equipment, and only after adding finish coatings, and a front baffle plate or brick wall for an adjustable exhaust opening to the forge, along with an adjustable secondary air choke installed on the burner’s mixing tube. These things are needed to raise internal temperatures high enough to better judge flame performance. Sounds backward, doesn't it? But the thing is that perfect evaluation only comes in equipment that has been turned into a radiant oven. Even as the burner’s flame is best judged in a cold forge, final evaluation of the burner’s effects of forge performance is judged by looking at the exhaust, and the level of incandescence on internal surfaces. The burner is merely part of the forge; if performance only revolved around the burner, most of what we have learned about constructing heating equipment would be "gilding the lily”—It is not. Back when I was still writing Gas Burners for Forges, Furnaces, and Kilns, I raised the temperatures in my forge enough that it changed from orange to lemon yellow, merely by refining the high-emission coating it was painted with (separating crude particles from its colloidal grade particles, using water). I A few weeks later, lemon yellow jumped up to yellow white by stopping all secondary air from entering the burner port; this can be further refined with the addition of a sliding secondary air choke on the burner's mixing tube. t has been stated that good burner performance is a delicate dance of different effects; ditto for the equipment it heats. The Two-gallon mini-forge Two 3/8" burners, mounted in a typical mini-forge; these are usually built from a two-gallon non-reusable helium cylinder (sold for inflating party balloons), or an empty non-refillable Freon cylinder (used by HVAC companies). So far as I know, Ron Reil first posted one of these forge sizes to the Net, back in the nineties. By law, empty non-refillable cylinders must be properly disposed of (which costs money), so they are not hard to talk businesses out of, once you explain what you want to do with them (they are only concerned about the chance of their being refilled). This size forge can be run from a single ½” burner, but two 3/8” burners give even heat, and can be used to turn this into a forge/furnace, like the coffee-can forge; or, they can be used to partition the forge, like the five-gallon model further on. Either way, the extra work to build and mount two burners will be handsomely repaid. A more recent variant on two-gallon tunnel forges, are mini-oval forges; these were first made from truck mufflers that were cut in half. But stainless steel oval trash cans can be made to serve with far less effort, for superior results; they should be run from two 3/8” burners, placed one-third of the way from its ends, and aimed up and toward the forge’s far side. Another variant on two-gallon tunnel forges is a two-and-a-half-gallon forge, shaped like a “D” laying on its side; these are made from one half of a five-gallon propane cylinder, cut lengthwise; this half has an exhaust opening cut into its front end, is lined with refractory, and rests on a 4” to 6” high steel pan. This pan is filled with various refractory layers; the additional height allows the bottom 2” of the pan to contain inexpensive Perlite, with tougher insulation layers of ceramic wool, etc. between it and the flame face. Where and what kind of burner or burners will be mounted varies from builder to builder. Five-gallon forges Five-gallon propane cylinders were used for most of the early home-made gas forges and casting furnaces; they are still the most popular container size for “tube” and “D” shaped forges; these forges are at their most efficient, when heated with two 1/2” size burners, placed low on the wall, but a little higher than the forge floor; aimed up and inward, so that the flame has the longest possible path to combust all oxygen in its induced air, before it can impinge on heating metal parts. With the burners placed at one-third the distance to the rear and forward ends of the cylinder. The far burner can be shut down, and a movable refractory baffle, placed midway between the burners, portioning off one-half of the forge, to save fuel, when heating small parts. This strategy works best on forges with a hinged and latched exhaust opening. Some people prefer using five-gallon paint cans, instead of discarded propane cylinders as shells. Five-gallons is the favorite size container being used for casting furnaces.

Drilling holes with rotary tools for 10-32 taps that are being used on small flame retention nozzles to thread holes for their socket set screws cab be done, if you are careful; these taps call for a #21 numbered drill bit, which is 0.1563” diameter; this is 0.030” larger diameter than the 1/8” shank limits of rotary tool chucks, so you need to enlarge the holes left by a 1/8” cobalt drill bit. Drill, and then file or grind, at one-half speed in a rotary tool. Enlarge the hole a little bit with a diamond coated rotary burr (safest) or a 1/8 single cut tungsten carbide rotary file (fast but tricky). You are removing only 0015” all the way around the hole’s periphery. So, you want a tool that works smoothly, and slow enough to keep control of the process. Swing the diamond coated burr lightly around the hole, and check to see if a taper tap will thread in the hole easily. If not repeat enlarging and checking. Be sure to keep track of how many passes produce the desired result. It is wise to perfect your technique on scrap tubing, before enlarging holes in your flame retention nozzle parts—especially if you choose to employ the rotary file.

Right there is all the difference between reading and doing. Without trying things out...

The short answer is yes. Amazon.com is a large marketplace. If you are able to tell good from bad products in that market, it is a useful choice; otherwise NOT!!! As to why we suggest 0-30 regulators over 0-20 models; it is just a matter of "just in case." I mess around with low volume higher pressure burners, and never need more than 20 PSI. In fact, most people spend most of their time at 12 to 15 PSI, even when welding in their forges. As to 0-60 regulators; the only time I ever use one is when I am testing a new burner design; and that is only to determine its safety limits.

Fine tuning the forge Fine-tuning burner performance completely is usually done while running it in its intended equipment, and only after adding finish coatings, and a front baffle plate or brick wall for an adjustable exhaust opening to the forge, along with an adjustable secondary air choke installed on the burner’s mixing tube. These things are needed in order to raise internal temperatures high enough to better judge flame performance. Sounds backward, doesn't it? But the thing is that the best evaluation only comes in equipment that has been turned into a “radiant oven.” The burner is merely part of the forge; if performance only revolved around the burner, most of what we've learned about constructing heating equipment would be "gilding the lily"; it’s not. Clear back when I was still writing Gas Burners, I raised the temperatures in my forge from orange to lemon yellow, merely by refining the high-emission coating it was painted with, from the stuff that came out of the jar to colloidal grade particles. I A few weeks later lemon yellow jumped up to yellow white by stopping all secondary air from entering the burner port; this has been further refined by the addition of a sliding secondary air choke on the burner's mixing tube. t has been stated that good burner performance requires a delicate dance of several factors; ditto for the equipment it heats.

People choose a variety of materials for the flame face layer; some merely toughen ceramic fiber blanket with rigidizer (colloidal silica; fumed silica suspended in water), and then add a thicker coating than normal of sealant and heat reflector over it. The point of this choice is immediate heating to very high internal temperatures. If time and fuel are at a premium, this is the way to go. If you want your equipment to last for years without the need to replace its refractory layers, a ½” layer of Kast-O-lite 30 is advised for a flame-face. Even rigidized ceramic fiber products still need to be sealed for safety. Furthermore, many of the coatings used for sealing provide a tough surface layer that holds high-emission coatings from peeling away from the fiber’s surface; an irritating problem that results from spreading some coatings directly on fiber blanket (especially when it is not rigidized first). Just as not all sealants are rated as high-emission, not all emission coatings are effective sealants, so you need to review the better-known products. There are also products, such as one shell coating for mold castings (consisting of zirconium silicate and fumed silica) which works quite well for surface sealing, and for heat reflection. I recommend this for those who do not want to include a flame face layer of Kast-O-lite 30. ITC-100: This is strictly a high-emission coating (not suitable for sealing); Twenty years ago, I found that deliberately separating it by adding more water to a small amount in a water glass, caused the non-colloidal particles to separate out, refining the coating, and greatly increasing its emission of radiant energy. My forge went from orange incandescence (when coated by the original product) to lemon-yellow, with just this change. I am not sure ITC 100 has the same ingredients today. You can make a better formula, for less money than this product now costs. 100% colloidal zirconium flour can be purchased from various online sources, and mixed with phosphoric acid from your grocery store, to make a high-emission coating, rated above (rather than “up to”) 90% “reflective” of radiant heat. None Stabilized zirconium dioxide (ZrO2; AKA zirconia) has three phases: Mono-clinic at less than 2138 °F (1170 °C), tetragonal between 2138 °F and 4298 °F (2370 °C). The transition between the first and second phase creates enough expansion to prevent it being used in hard refractory products, unless it is stabilized in the cubic form, or in its more useful partially stabilized tetragonal form. A small percent of calcium, yttrium, or magnesium oxides can be used to partially stabilize zirconia; cerium oxide can also be used, but is too expensive for this homebuilt equipment. Further high temperature manipulation can form fully stabilized zirconia, but adds further expense. Zirconia has very low thermal conductivity, yet very high luminosity when incandescent temperatures are reached. These two facts combine to make it a preeminent heat barrier. Because of the high luminosity, it can be used as an effective method of heat transference on high temperature casting crucibles, when applied in very thin coatings (.040” or less), and yet thicker coatings can be used to “reflect” heat through re-emission, while providing insulation that only improves as heat levels rise. When it comes to various heat barrier coatings, very fine particles of zirconium are desired, because the finer the particles the higher re-emission percentages go. Government sponsored experiments in the nineteen-sixties showed that phosphoric acid was able to hold stabilized zirconia onto heating surfaces despite phase change resizing; it was an important find—back then. But stabilized zirconia is much cheaper than it was in the past, and so this more expensive product is the better choice for tough heat barriers, and nowadays for some castable refractory crucibles. When used as a refractory; clumps of it are also used as insulation between crucibles and wire windings in induction furnaces. Zirconia based refractories, and alumina ceramics with stabilized zirconia included are well known for thermal shock resistance and resistance to erosion from incandescent liquid metals. Note: Drying can produce up to 4% shrinkage in slip cast zirconia refractories, and firing at 3452 °F (1900 °C) will produces up 15% further contraction; factors to be considered when planning structures made of it. Zirconia is available for use as grog, and is an effective loose insulation for very high heat environments (think of it as like Perlite on steroids). Zirconia also comes as stabilized ultra-high temperature porous insulating brick. Zirconium silicate: Many hobbyists concoct a tough sealant coating that is also a high-emission product; they purchase zirconium silicate flour from a pottery supplies store, and mix it with bentonite clay powder; this is practical, because it does not go through phase shifts. Zirconium silicate, while very tough is only rated at about 70% heat reflection; it is also very resistant to borax, and an economical choice. Zirconium silicate can be either a coating or a hard refractory layer, depending on the amount of bentonite clay, etc. it is mixed with. One of the hobby blacksmiths on IFI makes a slurry of Zircopax (a brand of zirconium silicate) mixed into to colloidal silica (AKA fumed silica) and a little water; he also uses this mix for shell casting; he suggests mixing it to about the consistency of latex paint, in a clear lidded jar. The Zircopax will settle out, once you stop stirring every few minutes, and cake on the bottom of the jar, with the silica and water remaining in solution over it; until it is broken up with a butter knife, and thoroughly remixed back into solution. When combined with silica as a binder, I believe the overall performance of Zircopax in thicker layers will prove to be considerably higher than 70% heat reflective, since the other part of its molecular structure is clear natural silicate, which will pass light rays with very little interference, and since its re-emissive mechanism is radiance, I believe its overall performance in thicker layers will prove to be much higher than it is rated for. Remember that each layer must be fired before the next layer is painted on. Tony Hansen, of Digital Fire fame, uses Zircopax as both a coating and a solid refractory, very like clay, but good to very high temperatures, and highly insulating; two qualities that mere clay lacks. Mr. Hansen mixes it with Veegum T (a smectite clay) as a binder and plasticizer. A mixture of 97% Zircopax and 3% Veegum can be molded into structures, as easily as potters clay. A mixture of 95% Zircopax and 5% Veegum provides a hard tough heat reflective coating for other refractory structures. Mr. Hansen has also created his own 5mm thick (just over 3/16”) kiln shelf, which he states “will perform at any temperature that my test kiln can do, and far in excess of that.” It consists of 80% Zircopax Plus, with 16.5% #60 to #80 grit Molochite grog, and 3.5% Veegum T; he states that the mixture is plastic and easy to roll out, with 4.2% shrinkage, with 15.3% water added, but suggests that you dry your forms between sheets of plasterboard, to prevent warping. Firing to cone 4 produced 1% shrinkage, and left his shelf only cinder bonded. Firing to yellow heat will produce further shrinkage, but strengthen the final product; this has about the same thermal shock resistance as high-alumina cast refractories. Avoid uneven heating by setting your forge or kiln up to work as a radiant oven. Read about Zircopax at: https://digitalfire.com/material/zircopax Read about Veegum at: https://digitalfire.com/material/1672 Plistix 900 F is a 94% corundum aggregate and matrix, with a phosphate bond; it can be either a coating or cast refractory, depending on the amount of water used; it is use rated to 3400 °F. This product can also be used as a firebrick mortar. Matrikote 90 AC Ceramic Coating (one of the product line from Allied Minerals) is a very tough hard fine grained high alumina refractory coating containing 90.4% alumina, 1.5 silicon dioxide as a vitreous(glass-like) binder, and 2.7 % phosphorus oxide as a polymerizing binder. Matrikote is good to 3000 °F, and would prove useful as an inner layer between outer coatings of higher use temperatures and rigidized ceramic fiber products. Satanite is probably the best-known refractory mortar that is also used as a hard coating/sealant over ceramic fiber board; it is use rated at 3200 °F, and is easily purchased in small quantities through knife making suppliers. But refractory mortars are not recommended as flame faces, so plan on using a different finish coating on interior surfaces; It is excellent on exterior surfaces. Sodium silicate is a white powder that dissolves in water; it is usually sold in bottles, with the water already added; it is commonly used to glue the little bits of Perlite together into a solid layer of tertiary refractory insulation, as both products melt at about 1900 °F. Sodium silicate is also used to glue refractory fiber products unto other surfaces, like the inside of forge shells (containers). However, when used this way, ceramic blanket should be rigidized completely through all layers, to keep it from de-laminating, and falling away from the glued surface over time. So, why use it at all then? Sodium silicate hardens through contact in the carbon dioxide in air; it does not need firing to work; fumed silica rigidizer must be fired.

When it comes to a layer (or layers) of thermal insulation, your choice should be dictated primarily by what is available at a reasonable price, if the insulation you choose can withstand your intended heat levels. Obviously, fiberglass batting will not do. Perlite (use rated to 1900 F) is not sufficient for use as a secondary layer of insulation; it must be relegated to a tertiary layer, unless it is only meant to leave air voids in castable refractory; then it is still relegated to a secondary layer, below a pure refractory flame face layer of 1/2" thickness. Perlite was used this way, quite successfully for years by hobby metal casters; it was mixed into Kast-O-lite 30 castable hard refractory; this is because it is an insulating refractory to begin with. Normally, ceramic fiber board is employed in square structures, and ceramic blankets is the logical choice for curved surfaces; this is a convenience—not a necessity. The smaller the equipment the more precious internal space becomes. One-inch-thick fiber board has the insulating value of two-inches of ceramic blanket. In miniature equipment, the increased expense and labor needed to use ceramic fiber board is a smart choice. Must you cut the board on complementary angles, to avoid gaps? No, but you do need to cut strips of board narrow enough to keep the wedge-shaped gaps small. The insulation from all these products depends on tiny air gaps within the material, for insulation. So, very small wedge-shaped gaps will not cripple the ability of the board to insulate. Or, fill wider wedge-shaped gaps with refractory cement, to reduce the number of strips you must cut. But do not attempt to use left over cement for a flame face layer; it will not work for that purpose.

That would be like comparing apples and oranges, as Venturi refers to the air entrance and burner body's shape, while Ribbon refers to a form of multi flame burner head, versus a (single) flame retention nozzle.

I don't think you are. For instance, what's behind all of that new looking rust on the outside of the burners? I can think of zero good reasons for such a rapid build up, and have never seen the like. Anyone in the viewing audience have a clue what's going on? I suspect that there is some source of water vapor that the burners and work pieces are being exposed to. Did you finish drying out the forge, before trying to heat steel up in it? You did at least drill on 1/8" drain hole in the bottom of the forge shell, right? "on"? Perhaps "one" would be a better move?

While the flames are a little washed out by ambient light levels, what I can see of them looks pretty good. Furthermore the tint of their blue color is not dark enough to indicate heavily oxidizing flames. It looks like, the answer to your problem isn't going to be very straight forward Thus, I must defer to Frosty to provide your answers No, no, Frosty. Honestly, there is no need to thank me for this. Why, I was glad to help out Also, the photos show a secondary flame envelope; this pretty much excludes the flames being oxidizing.

That gas orifice looks pretty big already. Before you go any further, how about posting a photo of the flames your forge is putting out now.

When it comes to a layer (or layers) of thermal insulation, your choice should be dictated primarily by what is available at a reasonable price, if the insulation you choose can withstand the heat. Obviously, fiberglass batting will not do. Perlite will not do in secondary insulation; it must be relegated to a tertiary layer, unless it is only meant to leave air voids in castable refractory; then it is still relegated to a secondary layer, below a pure refractory flame face. Perlite was used this way, quite successfully for years, when mixed into Kast-O-lite 30 castable; this is because it is an insulating refractory to begin with. Normally, ceramic fiber board is employed in square structures, and ceramic blankets is the choice for curved surfaces; this is a convenience—not a necessity. The smaller the equipment the more desirable internal space becomes. One-inch thick fiber board equals the insulating value of two-inches of ceramic blanket. In miniature equipment, the increased expense and labor to use the board becomes a reasonable choice. Must you cut the board on complementary angles, to avoid gaps? No; but you do need to cut strips of board narrow enough to keep the wedge-shaped gaps small. The insulation from all these products depends on tiny air gaps within the material. So, very small wedge-shaped gaps will not ruin the ability of the board to insulate. Or fill those gaps with refractory cement.