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Mikey98118

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  1. Forge sizes The so called one-brick Forge doesn’t exist. Originally, the term was applied to forges made from two hollowed out bricks, mounted facing each other; this size is good for fuel efficiency, when building very small objects, such as mouth harps, or chasing tools. Recently the term has come to be applied to very small box forges made from brick, and heated by canister-mount air/propane burners. These minuscule brick pile forges are about the smallest size that can breathe properly (back pressure issues) with air/propane burners. The original one-brick forges were heated with oxy/propane torches. You can see an example of this forge on the Net. Just input "One Brick Forge with Torch: The equivalent size in a tunnel forge would probably be a tomato-can forge. Next size up is the coffee-can forge, one-gallon paint-can forge, or half-muffler forge. Then comes none-refillable Freon and helium cylinder forges. Finally, we come to five-gallon propane cylinder forges, which nearly always turn out to be way to large for a beginner’s forge. As the half-muffler forge demonstrates, all these sizes have their equivalent in other forge shapes,".
  2. Heat reflective coatings: There are inconsistencies found in advertisements for "heat reflective" products; this is a legitimate label, if inexact. when, advertisements go further, and label various products as IR reflecting, they depart from reality. Yes, there actually are substances that reflect infrared energy; the most notable being gold (followed by silver and aluminum) mirror coatings. But the difference between cause and effect is important. Actual IR reflectors are only useful as ultra-thin coatings on optical devices, such as light filters in welding helmets, or camera lenses. High-emissivity coatings can be used to more effectively transfer heat through a crucible wall (as a thin coating), or to redirect energy, forming a heat barrier in thicker coatings; to illustrate the importance of the point, we will define a typical thin zirconia coating as one millimeter or less (.039") and thick coatings as three to five millimeters and up. The critical difference between a heat barrier and standard insulation is that the higher the heat level the more effective high-emissive coatings become, while insulation typically lose efficiency as heat levels rise. Also, the thicker the coating the more effective a re-emissive heat barrier becomes. Induction "furnaces" for instance, use crucibles made of nearly pure zirconia refractory, which is transparent to high frequency waves, but is so efficient as a heat barrier that with secondary insulating refractory between the electric coils and an inch or less of it outside the coils, a crucible becomes the whole furnace. The way a re-emissive coating works, is that it absorbs heat so readily that it quickly becomes incandescent. Think of a thin layer of tiny zirconium oxide particles exposed to a high heat source, and radiating that energy in all directions; now picture another layer of particles next to the first, with still other layers behind them. Each layer radiates heat in all directions, but the heat source only comes from one direction, so at every additional layer some heat gets subtracted as it is radiated back toward the heat source. So, a thin re-emissive coat will transfer lots of energy through a crucible wall, while the portion of heat it radiates back into the equipment is then re-radiated back at it, while the thicker coating on equipment surfaces reduces heat transfer that would otherwise happen through conduction. Re-emissive coatings are a simple but elegant form of recuperative energy generation. By converting combustion heat to radiant energy emission, heat gain from combustion is mostly retained on interior surfaces before the heated gas is lost out of exhaust vents, while heat loss through conduction is greatly reduced, with the added benefit of reducing heat stress on ceramic fiber insulation. Efficient heating equipment is designed for radiant energy to do most of the heating work, with combustion heat saved up on the radiant surfaces, so that direct heating from a flame becomes only a secondary heat source for the work. By the time your equipment interior reaches white heat, less than a third of combustion energy is directly heating metal parts or a crucible, while radiant heat is doing most of the work. Once you understand these principles, why movable exterior baffles coated with a high-emissive layer trumps looking for the best exhaust vent size should become obvious. Zirconium silicate (zircon) is about one-third silica, so it takes a thicker layer than zirconium oxide (zirconia) flour to do the same re-emission job, but then it is also far less expensive and much easier to employ. It is a fact that the smaller the particles of zirconia the greater the percentage of heat re-emission they create (as low as 68% versus as much as 95%). The zirconia particles trapped in the silicon matrix of commercial zirconium silicate are minuscule. Zirconia crucibles employ very crude particulates, and yet they are so effective as insulation that they become the entire furnace, when wrapped in a high frequency coil, and insulated by a further layer of loose zirconium oxide. So, the thicker the re-emissive layer on equipment interiors the better—always providing you use it in a manner that will stay attached. Hot-face heat reflectors can be as minimal as re-emissive coatings over ceramic board and rigidized blanket, or painted on a 1/2” thick layer of Kast-O-lite 30 cast refractory. But an armored tile of 5/32” to 3/16” thick made of homemade zirconium silicate “clay” has become a superior option, thanks to Tony Hansen’s famous Zircopax formulas on digitalfire.com: https://digitalfire.com/4sight/material/zircopax_1724.html If you're willing to take responsibility for understanding and using raw materials, there are a number of alternative choices, which beat the heck out of commercial heat barriers; not only costing far less money, but sometimes giving better performance at the same time. So called IR reflectors (actually high-emissivity coatings) will be of especial help in raising efficiency while protecting interiors of heating equipment; let's lay them out. The most effective commercial heat reflection coating claims "up to" 90% IR “reflection.” But, "up to" is actually a cover for the nasty truth that their formula can also mean as low as 68% heat reflection; it’s all a matter of zirconium oxide particle size. Being a naturally suspicious type, I tried separating the colloidal content from cruder particulates in the top commercial product by spooning some of their thick mud into a water glass, and presto; the crude stuff fell out of suspension in the mixture, and immediately sank to the bottom of the glass. So, I mixed in as much more mud as would separate, and painted the thinned-out coating over a previously coated and heat cured surface. My forge went from bright orange to yellow incandescence with the same burner and regulator setting. When it first came on the market, stabilized zirconia flour cost twice as much as the regular kind. Today, there are three different ways to stabilize zirconia, and the price has fallen to about one-third more than the regular stuff; this is an important factor to keep in mind. So, if colloidal particulates are so much more effective why have crude particulates in the commercial formula? MONEY; what is commonly called zirconia "flour" is nearly 100% colloidal, and will give you the full emissivity benefit; but it's not cheap. Zirconium oxide flour is the most effective heat reflector commonly available, but it changes its crystalline structure at about 900 °F, from cube to hexagon and then back again during cooling, so twice a heating cycle, it also changes particulate size, which is very hard indeed on every other ingredient in a hard cast refractory; not so slowly turning them to dust. And so, manufacturers of high heat crucibles (and others whose products justify the added expense) employ stabilized zirconia, mixed with a binder to make tough refractories and coatings. Simple zirconia based re-emissive coating: Published government sponsored experiments with zirconia coatings back in the nineteen-sixties tried a number of binders; the most successful was orthophosphoric acid (commonly called phosphoric acid); a readily available and inexpensive product that stays suspended in water; it has some interesting physical attributes. When painted unto a surface it is adhesive, and will hold zirconia particles suspended on walls and ceilings; when heated, it polymerizes, as the acid forms esters. Thereafter, it remains on the surface in a vitreous (glasslike) form at normal temperatures, and becomes soft and very adhesive above 365 °F (185 °C) from then on. Mixed with zirconia flour, this is a highly effective heat shield; but isn’t physically tough. On the other hand, it is easy to repair. Zirconium silicate: Zircon crystal is a substance that came into popular use, while manufacturers waited decades for reasonable stabilized zirconia prices; it is commercially known as zirconium silicate. Natural zircon crystal is silicon oxide and zirconium oxide, mixed in a stable tetragonal crystalline structure; it makes an end run around the size-change problem. Both zirconium and silicon are very resistant to flame erosion; they are both tough enough ingredients to make a superior hot-face coating. Zirconium silicate doesn’t start melting and separating out into its two constituents below 4650 °F (2550 °C); it is only about 75% heat reflective as thin coats (.040”). Zirconium silicate is reasonably priced, and easily mixed with a binder; you can build up thick coats of it. Zirconium silicate re-emissive coating: Zircopax 95% by weight to Veegum or bentonite 5%. Hot-face formula: This recipe came from a potter’s supply store. It has ingredients that physically toughen, resist strong alkalis, and reflect heat. The (ingredients (by volume) are: one-part alumina hydrate; one-part kyanite (35mesh); one-part Zircopax; half part Veegum T or bentonite. Heat reflective coatings: There are inconsistencies found in advertisements for "heat reflective" products; this is a legitimate label, if inexact. when, advertisements go further, and label various products as IR reflecting, they depart from reality. Yes, there actually are substances that reflect infrared energy; the most notable being gold (followed by silver and aluminum) mirror coatings. But the difference between cause and effect is important. Actual IR reflectors are only useful as ultra-thin coatings on optical devices, such as light filters in welding helmets, or camera lenses. High-emissivity coatings can be used to more effectively transfer heat through a crucible wall (as a thin coating), or to redirect energy, forming a heat barrier in thicker coatings; to illustrate the importance of the point, we will define a typical thin zirconia coating as one millimeter or less (.039") and thick coatings as three to five millimeters and up. The critical difference between a heat barrier and standard insulation is that the higher the heat level the more effective high-emissive coatings become, while insulation typically lose efficiency as heat levels rise. Also, the thicker the coating the more effective a re-emissive heat barrier becomes. Induction "furnaces" for instance, use crucibles made of nearly pure zirconia refractory, which is transparent to high frequency waves, but is so efficient as a heat barrier that with secondary insulating refractory between the electric coils and an inch or less of it outside the coils, a crucible becomes the whole furnace. The way a re-emissive coating works, is that it absorbs heat so readily that it quickly becomes incandescent. Think of a thin layer of tiny zirconium oxide particles exposed to a high heat source, and radiating that energy in all directions; now picture another layer of particles next to the first, with still other layers behind them. Each layer radiates heat in all directions, but the heat source only comes from one direction, so at every additional layer some heat gets subtracted as it is radiated back toward the heat source. So, a thin re-emissive coat will transfer lots of energy through a crucible wall, while the portion of heat it radiates back into the equipment is then re-radiated back at it, while the thicker coating on equipment surfaces reduces heat transfer that would otherwise happen through conduction. Re-emissive coatings are a simple but elegant form of recuperative energy generation. By converting combustion heat to radiant energy emission, heat gain from combustion is mostly retained on interior surfaces before the heated gas is lost out of exhaust vents, while heat loss through conduction is greatly reduced, with the added benefit of reducing heat stress on ceramic fiber insulation. Efficient heating equipment is designed for radiant energy to do most of the heating work, with combustion heat saved up on the radiant surfaces, so that direct heating from a flame becomes only a secondary heat source for the work. By the time your equipment interior reaches white heat, less than a third of combustion energy is directly heating metal parts or a crucible, while radiant heat is doing most of the work. Once you understand these principles, why movable exterior baffles coated with a high-emissive layer trumps looking for the best exhaust vent size should become obvious. Zirconium silicate (zircon) is about one-third silica, so it takes a thicker layer than zirconium oxide (zirconia) flour to do the same re-emission job, but then it is also far less expensive and much easier to employ. It is a fact that the smaller the particles of zirconia the greater the percentage of heat re-emission they create (as low as 68% versus as much as 95%). The zirconia particles trapped in the silicon matrix of commercial zirconium silicate are minuscule. Zirconia crucibles employ very crude particulates, and yet they are so effective as insulation that they become the entire furnace, when wrapped in a high frequency coil, and insulated by a further layer of loose zirconium oxide. So, the thicker the re-emissive layer on equipment interiors the better—always providing you use it in a manner that will stay attached. Hot-face heat reflectors can be as minimal as re-emissive coatings over ceramic board and rigidized blanket, or painted on a 1/2” thick layer of Kast-O-lite 30 cast refractory. But an armored tile of 5/32” to 3/16” thick made of homemade zirconium silicate “clay” has become a superior option, thanks to Tony Hansen’s famous Zircopax formulas on digitalfire.com: https://digitalfire.com/4sight/material/zircopax_1724.html If you're willing to take responsibility for understanding and using raw materials, there are a number of alternative choices, which beat the heck out of commercial heat barriers; not only costing far less money, but sometimes giving better performance at the same time. So called IR reflectors (actually high-emissivity coatings) will be of especial help in raising efficiency while protecting interiors of heating equipment; let's lay them out. The most effective commercial heat reflection coating claims "up to" 90% IR “reflection.” But, "up to" is actually a cover for the nasty truth that their formula can also mean as low as 68% heat reflection; it’s all a matter of zirconium oxide particle size. Being a naturally suspicious type, I tried separating the colloidal content from cruder particulates in the top commercial product by spooning some of their thick mud into a water glass, and presto; the crude stuff fell out of suspension in the mixture, and immediately sank to the bottom of the glass. So, I mixed in as much more mud as would separate, and painted the thinned-out coating over a previously coated and heat cured surface. My forge went from bright orange to yellow incandescence with the same burner and regulator setting. When it first came on the market, stabilized zirconia flour cost twice as much as the regular kind. Today, there are three different ways to stabilize zirconia, and the price has fallen to about one-third more than the regular stuff; this is an important factor to keep in mind. So, if colloidal particulates are so much more effective why have crude particulates in the commercial formula? MONEY; what is commonly called zirconia "flour" is nearly 100% colloidal, and will give you the full emissivity benefit; but it's not cheap. Zirconium oxide flour is the most effective heat reflector commonly available, but it changes its crystalline structure at about 900 °F, from cube to hexagon and then back again during cooling, so twice a heating cycle, it also changes particulate size, which is very hard indeed on every other ingredient in a hard cast refractory; not so slowly turning them to dust. And so, manufacturers of high heat crucibles (and others whose products justify the added expense) employ stabilized zirconia, mixed with a binder to make tough refractories and coatings. Simple zirconia based re-emissive coating: Published government sponsored experiments with zirconia coatings back in the nineteen-sixties tried a number of binders; the most successful was orthophosphoric acid (commonly called phosphoric acid); a readily available and inexpensive product that stays suspended in water; it has some interesting physical attributes. When painted unto a surface it is adhesive, and will hold zirconia particles suspended on walls and ceilings; when heated, it polymerizes, as the acid forms esters. Thereafter, it remains on the surface in a vitreous (glasslike) form at normal temperatures, and becomes soft and very adhesive above 365 °F (185 °C) from then on. Mixed with zirconia flour, this is a highly effective heat shield; but isn’t physically tough. On the other hand, it is easy to repair. Zirconium silicate: Zircon crystal is a substance that came into popular use, while manufacturers waited decades for reasonable stabilized zirconia prices; it is commercially known as zirconium silicate. Natural zircon crystal is silicon oxide and zirconium oxide, mixed in a stable tetragonal crystalline structure; it makes an end run around the size-change problem. Both zirconium and silicon are very resistant to flame erosion; they are both tough enough ingredients to make a superior hot-face coating. Zirconium silicate doesn’t start melting and separating out into its two constituents below 4650 °F (2550 °C); it is only about 75% heat reflective as thin coats (.040”). Zirconium silicate is reasonably priced, and easily mixed with a binder; you can build up thick coats of it. Zirconium silicate re-emissive coating: Zircopax 95% by weight to Veegum or bentonite 5%. Hot-face formula: This recipe came from a potter’s supply store. It has ingredients that physically toughen, resist strong alkalis, and reflect heat. The (ingredients (by volume) are: one-part alumina hydrate; one-part kyanite (35mesh); one-part Zircopax; half part Veegum T or bentonite. Please understand that these are by no means the only heat reflecting coatings. You can find others discussed on this forum. Furthermore, some seal coatings, such as Plistex 900 will re=emmit about 75% of IR back from their surfaces.
  3. It has been pretty clear for the last five years that continuing burner improvements are sun-setting stainless-steel nozzles. refractory is the way forward.
  4. Okay, now you have me drooling. I have been looking for a high heat smooth surfaced refractory, which is not inclined to crack from the fast thermal cycling encountered by flame retention nozzles.
  5. Hot-face materials Plistix 900F® is a fire clay consisting of 94.1% aluminum oxide, and 1.7% silicon oxide, with 1 to 5 % aluminum phosphate; it is in many ways the premier example of a thin hot-face seal coating and is recommended for use over ceramic fiber blanket (not recommended over ceramic fiber board), or solid refractory products: it is a general service sealant that forms a protective thermal barrier for ceramic fiber blanket insulation; air setting to a hard set. Plistix is sold as powder, and is mixed with tap water to a consistency of sour cream; then dabbed on from a disposable paint brush in 1/16” thick layers (each layer will coat 1.2 square feet per 1lb. of powder). After application, seal equipment interior with plastic, and allow the coating to dry slowly at temperatures above 60 degrees to a hard set. Post drying, fire the first layer and all subsequent layers can be applied with brush strokes. Bring the coated equipment up slowly to temperature, to avoid cracking and other damage from thermal shock. Air dry and fire every subsequent layer before adding additional coats. Kast-O-lite 30 insulating castable refractory poured in a 1/2” thick layer gives a large measure of thermal protection, along with mechanical armoring, in case you are moving tongs in and out of your equipment, and for general shop safety; it is use rated to 3000 F, is alumina based for flux tolerance, contains mini spheres for insulation, and is very resistant to thermal shock; it weighs 90 lbs. per cubic foot (compared to 146 for regular refractory). Kast-O-lite 30 has been the favorite refractory for construction of home-built forges and casting furnaces for over twenty years. This refractory hardens gradually enough that the edges of equipment surfaces can be scraped with a straight edge, so that those surfaces meet properly, allowing two-part forges and furnaces to run with only minor flame leakage. Of course you can further refine the seam faces with cement facing to stop flames completely. Kast-O-lite 30 has a moderate insulating value of great importance for protecting insulation layers from heat damage; when coupled with a re-emissive (heat reflective) finish layer, it will greatly lengthen the working life of secondary insulation. Kast-O-lite 30 will stick to most materials. Use cooking spray, Crisco, or car wax on plastic or wood molds as a release agent. I have also used glass jars as forms, and then shattered them with heat and water after the refractory was cured. Cardboard and wax candle molds both burn away conveniently.
  6. Castable refractories: There are several good castable refractories used as flame faces in forges, and casting furnaces. So far, I think Kast-O-lite 30 serves best in both equipment.
  7. Thanks for showing us what the product was. I bought mine through Amazon.com yesterday, with free shipping. I just love freed shipping on refractories
  8. No sweat Frosty. Anyway, it has opened up the discussion; and that may give me a better handle on the issue than I have at present. The Greeks had it right about the nature of truth. Nevertheless, I keep reaching for it. Thankfully, this is only a hobby
  9. Frosty, Sorry for the late reply. This time Kathy was in the hands of the doctor gods (and people actually think old age is boring). Waffling? No; people do that to cover their six; not to risk it. I stated something as fact in my book notes, that I don't KNOW to be fact. That bugs me, big time! As for leaving you feeling like you were swinging in the breeze, I apologize. I am genuinely sorry for that.
  10. Flame tight is an admirable goal, but flame restrictive may be all you actually need. Remember that the internal forge pressure isn't raised much above atmospheric levels, with these burners; otherwise, they suffer from back pressure.
  11. As to the flames; they are what I describe as" blue ribbon." Congratulations on your work Well, they state that this refractory is good for ladles, and for thermal combustors. Therefore, I think it would probably work fine as a forge floor. I have been kind of looking to use for a refractory for in ceramic flame nozzles, and this looks like it/ Thanks for the tip
  12. MIG tip update I have been advising people to buy their MIG contact tips online for years, because they had so many bad experiences when trying to buy them from regular welding supply stores. When you ask a sales clerk for a single MIG tip (as so many people did), they will usually just lie about them being available, to get rid of you as fast as possible. Everything changes in the marketplace. Today, most of these stores have packages of MIG tips on display. You can buy five tips at a reasonable price, making an end-run around the usual awkward scene with a sales clerk. In the meantime, online sources now mostly sell imported tips, and these can very wildly in quality.
  13. That would certainly be up to snuff, in most ways. What is missing is any background information about how well it holds up under the fast temperature changes that happen in gas forges. Most refractories with that high an alumina content are used in glass working equipment (which has sustained high temperatures and very slow heating and cooling cycles) , or for crucible in especially high heat foundry work. Mind you, the refractory might be just fine. I would love to here what brand it is. But, one of the reasons we keep recommending Kastolite 30, is that it is thoroughly well known to be satisfactory for use in gas forges. Having your refractory crack, is such a major downer
  14. Putting all my cards on the table... I'm absolutely, mostly, only kind of sure; it's still a reach, and that has bugged me for several years. There; I've fest up
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