Johnny Chesser Posted March 16, 2018 Share Posted March 16, 2018 I have built my own forge and I’m getting feedback that I should not have used plaster of Paris and play sand, that it is a heat sink. Is this true? Quote Link to comment Share on other sites More sharing options...
JHCC Posted March 16, 2018 Share Posted March 16, 2018 Hello, and welcome to IFI. If you have not already, please READ THIS FIRST!!! The short answer to your question is, "Yes, and more." It's a bad idea, don't do it, and if you want more information, read the post I just linked and do what it says there. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 16, 2018 Share Posted March 16, 2018 Welcome aboard Johnny, glad to have you. POP and most anything is not a refractory. At best it will erode quickly at worst it can spall and throw bits of HOT plaster around the shop. Iforge has a LARGE gas forge section with all a person needs to know. Forges 101 is the most current active thread and has info about forges, liners and safety. We're REALLY BIG on safety here. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Johnny Chesser Posted March 16, 2018 Author Share Posted March 16, 2018 I’ve ran about 250-300 lbs of L.P through it with very little flaking and zero spalling, my meter only goes up to 1400 degrees and it maxed out in less than a minute? Quote Link to comment Share on other sites More sharing options...
Latticino Posted March 16, 2018 Share Posted March 16, 2018 But can you forge weld mild steel using it? Quote Link to comment Share on other sites More sharing options...
Johnny Chesser Posted March 16, 2018 Author Share Posted March 16, 2018 Yes, we’ve made a couple of Damascus blades already. Only about6” long Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted March 16, 2018 Share Posted March 16, 2018 You made Damascus blades from mild steel? The point is mild steel has a higher forge welding temperature than high carbon steel. Regardless, if you are able to forge weld high carbon steel with it you are getting pretty darn hot. However, the fact that the plaster of paris DIY "refractory" is a heat sink compared to commercial refractory and ceramic fiber blanket still remains. If/when you change your lining or build a new forge with more appropriate materials you will most likely notice a difference in fuel consumption. Is that 1400 degrees C or F? If you like how everything is working then more power to you, but it's almost a certainty that you are burning significantly more fuel than you would be with the recommended materials. If you do a fair amount of forging then the cost of the extra propane will probably exceed the savings of using plaster of paris in a short period of time even if it holds up well and doesn't fail in a way that injures you or anyone else. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted March 17, 2018 Share Posted March 17, 2018 Plaster of Paris is reasonably insulating, but a poor bonding agent, mechanically speaking. The sand makes a reasonably tough grog, but is very poor insulation; result? A poor choice of "refractory." Quote Link to comment Share on other sites More sharing options...
Irondragon Forge ClayWorks Posted March 17, 2018 Share Posted March 17, 2018 22 hours ago, Johnny Chesser said: I’ve ran about 250-300 lbs of L.P through it At our current price of propane, that's about $160.00 U.S. 300lb= 71 Gal @ 2.25 a gallon. Where are you located and how long did it take to use that much propane? https://www.iforgeiron.com/topic/48833-read-this-first/ Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 21, 2018 Share Posted March 21, 2018 Not to mention that Plaster of Paris starts to degrade around 450 deg F and we will be wanting to use it at over 1000 degrees higher temps! Quote Link to comment Share on other sites More sharing options...
WayneCoeArtistBlacksmith Posted March 21, 2018 Share Posted March 21, 2018 Check out the Build a Gas Forge at the Forge Supplies page on my web-site. You can find the url and other contact info on my profile. Let me know if I can help you. I prefer e-mails. Wayne Quote Link to comment Share on other sites More sharing options...
Nghtmrknife Posted April 23, 2018 Share Posted April 23, 2018 I've used the plaster of Paris and playsand mix in my 20lb propane forge. After about a month of use and not heavy use at all, the plaster degraded enough that I could not use the forge anymore. I tipped the forge up and it all fell out. Quote Link to comment Share on other sites More sharing options...
Daswulf Posted April 23, 2018 Share Posted April 23, 2018 Ugh, just saw KORs pop/sand mix mini foundry come up on an instructables email. It just won't die. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted April 23, 2018 Share Posted April 23, 2018 "Something for nothing" has a long half-life. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted April 23, 2018 Share Posted April 23, 2018 Bad information keeps getting forwarded by people who do not know enough to know it's bad information. It's the internet! Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted April 28, 2018 Share Posted April 28, 2018 Oh, but it must be true; its written down in black and white! Quote Link to comment Share on other sites More sharing options...
JustAnotherViking Posted April 28, 2018 Share Posted April 28, 2018 Like Abraham Lincoln famously said; 'never trust anything you read on the Internet' Quote Link to comment Share on other sites More sharing options...
Trevor Colin Posted October 21, 2019 Share Posted October 21, 2019 We've been watching YouTube and I want to make a forge with my 11 year old grandson and don't want to disappoint him so if plaster of Paris is not the best thing to use what should I use? I planned on plaster of Paris and sand. Quote Link to comment Share on other sites More sharing options...
Kozzy Posted October 21, 2019 Share Posted October 21, 2019 8 minutes ago, Trevor Colin said: We've been watching YouTube Watching youtube can give you some good general ideas to *think* about...believing youtube to be a good definitive source is where people get in trouble...sometimes dangerously so. In the areas of forge building, probably about 90% of what's there is just people repeating what others got wrong. If you look in the forums tab of this site under gas forges, you will find "stickies"...some excellent information that was pinned there to be helpful forever. Among those in the section is a lot of peer-reviewed information on how one should properly build a gas forge. Sometimes it takes a while to sort through but if you dive in, it will start making sense. Quote Link to comment Share on other sites More sharing options...
Irondragon Forge ClayWorks Posted October 21, 2019 Share Posted October 21, 2019 Welcome aboard. Have you read this yet? READ THIS FIRST If you edit your profile to show your location it will help with answers because many are location dependent. I hope after reading this thread you have scraped the PoP & Sand. There are many discussions in the Forges 101 thread about lining a forge. Generally it's rigidized fiber like K-O-Wool or equivalence with a hard facing of castable refractory like Satanite or Kast-O-Lite. Quote Link to comment Share on other sites More sharing options...
Ohio Posted October 21, 2019 Share Posted October 21, 2019 18 minutes ago, Trevor Colin said: We've been watching YouTube and I want to make a forge with my 11 year old grandson and don't want to disappoint him so if plaster of Paris is not the best thing to use what should I use? I planned on plaster of Paris and sand. Trevor Colin, are you planning a propane forge? If not, may I suggest a charcoal forge based on Charles Stevens's JABOD (Just A Box Of Dirt). A JABOD has a lot to recommend it---low cost and uses a lot of basic skills, such as digging clayey dirt, sifting clayey dirt, and building with clayey dirt. You can build one quickly and be forging the same day. Fuel can be coal but to make it easy, get some lump charcoal from the grocery store (not Briquettes---that's the wrong stuff) that's actually made from wood. You can also use coal---like from a mine---but I'm not familiar with that fuel. There are a ton of people in the Solid Fuel Forges subforum, though, who use it and can guide you. What's nice about charcoal is that it's fairly easy to find and if you don't use the whole back, you can grill up some dinner. JABOD forges are fun, and you get a real sense of how and why forges work the way they do. And you and the grandkid will find out really fast if blacksmithing is something you want to pursue. Then if you decide you want to build a propane forge, there are a lot of threads on design, build, and safe use of these types of forges here. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted October 21, 2019 Share Posted October 21, 2019 Plaster of Paris starts to degrade around 1000 degF below good forging temps. It is also not an insulating refractory and so it drives up fuel costs. Videos advocating it's use are indications that any idiot can post a video. Knowing how to sift the wheat from the chaff is the problem. The thread mentioned will teach you how to search this website for answers; please read some of the comments to those answers as we ride herd on them and try to make sure that bad answers don't propagate. Quote Link to comment Share on other sites More sharing options...
Frog50 Posted November 22, 2019 Share Posted November 22, 2019 So, I just got back from Home Depot where I bought pop and play sand. Seriously, walked in the door fifteen minutes ago. Woe is me. I’m making a small foundry rather than a forge and want to case harden some steel. So what material should I use instead of the pop and sand? Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted November 22, 2019 Share Posted November 22, 2019 What do you want to cast? Aluminum, Brass, Bronze, cast iron, steel, platinum, tungsten? The material you cast will control what you need to use as a refractory. Probably kaowool like is used in a propane forge will work for you---properly coated of course---if you will be building a propane foundry! What fuel will you be using?---Yes this is in the gas forge section but we have had folks make that mistake before too. How large a foundry? How often will it be used? It's difficult to give good answers when there are not enough details provided. BTW I'm off till Monday in a couple of minutes; others will have to help till then. Quote Link to comment Share on other sites More sharing options...
Frog50 Posted November 22, 2019 Share Posted November 22, 2019 I’m sorry, I just signed up and I didn’t realize there were different areas for different interests. I’m going to be using charcoal since I make it myself, and I’m going to be melting aluminum for prototypes and case hardening steel also for prototypes. Quote Link to comment Share on other sites More sharing options...
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