How to easily Insulate Your furnace (foundry) using plaster - by VOGMAN

[@xrexc3179]

I leaned completely by accident that by adding some granulated clay to the mix will increase the strength tremendously. I live in NW FL and have a lot of red clay in the soil. The first time I made plaster refractory I simply used sand out of the yard as it is mostly silica. I also knew that the sand contained a fair amount of clay because the sand had a red tint to it. Well the result was a small forge that lasted me over 3 years. It did form a few cracks early on but they weren't all the way thru so it remained in 9ne piece and continued to do so thru prolly 200+ firings. Unfortunately I can't give you a ratio but I think a little trial and error will get ya where ya want to be

[@geraldmartin8195]

Interesting that people comment on your accent and delivery. The first of your videos I watched mostly because of your voice. But now I watch them all because of the content as well. I have a lot of casting experience both commercially, but always add more and with an interesting and unorthodox perspective. Sculpture is my field. Thanks from Canada.

[@vogman]

Hi Gerald. Believe me, my voice is completely UNremarkable. I'm always flattered to hear comments about it, but prior to KZbin no one ever said a word. Perhaps it's a case of the unusual being appealing. For instance, I think most people find the French have a very sexy accent, though presumably this is lost on the French (and maybe French-Canadian's?). It's always great to have another professional commenting on my channel. I enjoy casting but I'm very much an amateur. Please feel free to offer insight on any of my videos : )

[@geraldmartin8195]

@@vogman Thank you for your reply. I have travelled a fair amount and I must disagree somewhat with your voice comments. If you were to travel throughout N. America and listened to many different people talk, you would perceive how incredibly bland is the overall sound. (Immigrants help spruce it up, though.) . I am flattered that you would read any of my insights on your work. Although I'll keep it in mind, I might be inhibited by your creative uniqueness.

[@j.w.m.rhynejr9766]

Great video for the building & re doing your foundry!!! Thanks for sharing!!

[@katecoombes1000]

That's perfect. I'm going to put mine in the ground but it's in really in a 44lt drum filled with dirt. I figure dirt is one thing that takes every kind of weather. South Australia gets pretty hot so I'm going with and idea that just might work.

[@vogman]

Hi Patrick. I'm more than happy to exchange personal emails with like-minded folk : ) You can send a private message via KZbin, but you might find it quicker and easier to write via my website here- vegoilguy.co.uk/contact_me.php Just send a message through the form using your email address. Once received, I'll email back with mine. Look forward to hearing from you mate. Geoff

[@katecoombes1000]

Hi VegOilGuy, if you have a look at my videos, I'm using my old system and not your design yet. Still working on different set ups.

[@brettbaratheon9776]

Hello from Milwaukee, Wisconsin, USA! Not only are your videos marvelous, but your voice/accent is awesome. We enjoy the narrating! It's like.....David Attenborough ;) keep up the great work. New subscriber!

[@vogman]

Thanks Brett. I enjoy sharing my ideas and if they entertain or inspire others then I'm thrilled. As for David Attenborough, I'm not so sure I could ever measure up to a great man like that : ) Thanks for subscribing. All the best. Geoff

[@brettbaratheon9776]

+VegOilGuy- my first question: I've been playing around with the furnace mixtures (new foundry-man, started about 2 months ago....obsessed). Can I mix Perlite in with the plaster of Paris and sand mixture for durability? I reinforce the furnace with stainless steel wool already and it hold pretty well. Looking more more stability, not ready for the concrete yet I think. Please and thank you!

[@vogman]

Hi Brett. As long as you're not spending more time or money than you're comfortable with, you really can't go wrong. Personally I feel that the foundry walls are best made from refractory which is the professional product with a long life span and excellent results. That doesn't mean there isn't a cheaper alternative method - and you might be the one to find it. For me I find experimenting to be the real fun part and I get the impression you're the same. So go for it my friend and feel free to let me know how you get on. We're all still learning after all : ) If in doubt, make small block of your chosen mixes (or varying ratios perhaps). Place these inside your foundry and heat the heck out of them. See how they perform... you might discover something incredible. Best wishes, Geoff

[@brettbaratheon9776]

+VegOilGuy-that is a really good idea! I also learned, may have been from one of your videos, that it's better to add the mix to the water, and not the water to the mixture. That is for the advice. You are quite modest. Watching what you're cooking up over there is FAR beyond the point I'm at........you're semi-pro ;) I'm an total amateur

[@vogman]

People like Martin (mentioned in my last video) are the real professionals. They have to do it even when they don't want to. We amateurs do it for fun. As for plaster, I have mentioned that in my foundry insulation video I think. In quantities like that it's very important to add water first. Otherwise you're forever chasing out clumps. Just try not to overdo the water otherwise you'll find yourself needing bigger and bigger mixing containers. Thanks again for the kind words. You're clearly a gent!

[@tylerkrug7719]

Great idea to slowly dry it out with small fires

[@vogman]

Thanks. Sometime slow is best : )

[@theartoftech]

I love that all of your videos are so clear and go step by step. You deserve 700,000 subscribers :)

[@vogman]

That's very kind, thanks

[@Yhrim70]

Idea: I know you added the insulation after your original build. But if this was done during the build, you could have Two Metal containers, one that is about 2 inches smaller than the other. The smaller one would be the size of your main exterior. Then between these two, insulation could be packed in and etc. Then on the inner container, you could make the same way you made yours. This is the same basic principle in building a good wood gasifier. Just my thoughts, I've been thinking about how to design mine. Been planning on this for a couple years now, hope to actually get it built this summer.

[@seymourpro6097]

Plaster is Gypsum (calcium sulphate) When hard it's a tetrahydrate form you've added water and it hardens! If you then heat it above 400C the tetrahydrate dehydrates to a hemi hydrate and loses it's strength. There are many uses for a plaster/sand kiln but it's not a long lasting as calcium silicate thermal insulation lagging which is good to well over 1000C and a lot lighter. Search Vitcas among other suppliers, it's even available from RS!

[@johngray4988]

a few years ago, a friend and I built a small foundry. we experimented with the plaster/sand ratios first and found that 3/1 ratio was the strongest(all others we tried, you could scrap a line in it with your thumb nail). it may have been the brand of plaster of paris we used, you should experiment yourself, and see what works best for you. I will definitely be adding pearlite or vermiculite next time.

[@randallmarsh446]

I used plaster of paris and perlite....I mixed the plaster very thin and tamped the perlite with a wooden stick .

[@pedroernestobraga]

Hello VegOilGuy, thanks for these tip about plaster, in true plaster and sand is a great insulation but it tend to fall of after some meltings, but how here in Brazil refractory materials are hard to get, I tried use some secular tecniques, using a yellow mud used to made bricks here in my region, so I made a wall with plaster, and covered it with these mud work great

[@vogman]

Excellent advice Pedro. Thanks : )

[@crespoandrade]

man! you are a one cool guy! greetings from south Portugal! i am going tomorrow to get all my bits for the veg oil settling tank because of your videos, and funny enough i am also working on a foundry and guess what you also have a video on it..... many thanks for your hard work and for sharing!

[@vogman]

Thanks Dave. That's great to hear. For a long time waste cooking oil was a terribly underused resource that had fabulous potential. I'm pleased more people are taking an interest in recycling and re-purposing this waste product. Plus it can be put to fun uses like casting ; ) Please look out for a casting video from me this Friday.

[@TheBazFella]

Excellent video mate, and a brilliant idea. I'm trying to build a primitive-style fireplace in me shack out the back yard, Ive tried making a few samples with perlite/cement/sand etc., just waiting for them to dry out fully then going to flame test them. Inspirational vid, thanks for sharing Baz

[@vogman]

Plaster is cheap, easy to work and fairly reliable IF you contain it. It will crack and crumble if it isn't sandwiched in something. I toyed with mixing perlite in with my plaster as well. : )

[@JRock17991]

Thanks for posting these! great vids. You can increase the insulative properties of the plaster by adding a good amount of Pearlite (Vermiculite if you can't find the pearlite). My guess would be a 1:2:3 Mix. That'd also make your plaster go farther.

[@vogman]

Many thanks : ) I did toy with Pearlite etc but I really was looking for budget, so spending money was not ideal. A large bag of plaster was very cheap and it's done an amazing job. It's still together now. But that doesn't mean there aren't better solutions out there. The addition of pearlite could well improve things. Thanks for the input : )

[@allensayers4941]

Love your videos that's why I'm now subscriber thank you

[@vogman]

Great to have you here Allen : )

[@victoryfirst2878]

Would using this plaster mix inside a wood stove survive the rough treatment of logs getting thrown inside the stove ??? How long would this last inside the stove ?? Thanks

[@vogman]

Plaster is very soft. I would imagine it would fall apart quickly.

[@lvd2001]

Keep the videos coming - I am a fan of you

[@vogman]

Thanks Liem : )

[@lelearmi6186]

a 20 awg kanthal resistor powered by 230 volts alternating current; how many centimeters to work best?

[@catherineharris4746]

Fkng outstanding!👍👍👍👍👍

[@Dollapfin]

Mix that plaster with FINE sawdust then put it in. High temps will combust the sawdust inside or at least pyrolize it. This will make a super insulative ceramic-like substance.

[@vogman]

Interesting. Never heard of that idea : )

[@tomharrell1954]

Thanks VOG!!! Much appreciate the info

[@vogman]

No problem 👍

[@HWolfpaws]

Hm... few ideas for refractory... plaster of paris i really better option since it s really used in also jewellry casting and it s super stable. Only issue is that it should not be touched, and the temperature cycle should definetly not be extreme.

[@cinemaipswich4636]

There is something called "micro balloons". It is used in the "fiber glass" industry. They are tiny balloons of glass with air inside them. Perhaps mixing it with plaster will help with heat loss.

[@CCoburn3]

Have you considered perlite or vermiculite instead of sand? Both of them have good insulating properties and can withstand high heats.

[@vogman]

I've heard this said : )

[@andrevdv1171]

Thanks for the tips, is the insulation holding up

[@vogman]

Actually as an external insulation the plaster works well and whilst it has cracked, it's still held together 😁

[@scott98390]

I wonder how it would go if you impregnated the plaster with chopped fiberglass... do you think that would reduce the cracking?

[@vogman]

You know what Scott, I've honestly pondered on that myself. I was going to coat the outside of my foundry with Fibreglass. Still might. Love the stuff. These days a lot of concretes are being made with fibreglass-like strands added. It pours just the same but the fibres helps everything bond. If you ever give it a try, let me know. I've love to hear how it goes. Best wishes, Geoff

[@SkullyWoodMetal]

My furnace is built with fire brick and refractory. It needs more insulation. Great inspiration.

[@vogman]

I've been amazed by how good plaster is as an insulation. I've just finished melting some aluminium and it's great to see the metal glowing red. That's heat retention in action. It will crack, so it needs to be encased in something (but not perspex) and it won't last forever. But I'm a few months in and a lot of uses later it's still working great. If I have to replace it in a year or two or three, for the low cost and the ease of build, it will be worth it. All the best, Geoff

[@Mark6E]

Have you tried perlite/sodium silicate? It seems to be a lot more durable than plaster and quite cheap. Im going to make one next week using this as the refractory, possibly thin coating of fireclay on the inside.

[@vogman]

Hi Mark. No it's not something I've tried, but I have heard about it. Let me know how you get it. I'd be interested : )

[@perpetuant5452]

Great idea. The perspex was too thick and you should have heated it with a heat gun taking you time to let the plastic soften and take form probably.

[@markman63]

Why not use the refractory cement for the whole thing?

[@halletts1171]

Good Video! Thanks for the info.

[@vogman]

No problem!

[@waskasoometalworks3329]

could I recommend Roxul? its mineral wool made from spinning molten basalt, excellent fireproofing and soundproofing, generally pay $60 a bundle Canadian for it. I use it for commercial firewalls and firecaulking doesn't allow flame spread. I haven't tried it my forge but when I get a few extra batts I plan on it

[@vogman]

High Jason, of course you can recommend mineral wool. I'll be honest I was looking for a very cheap insulation material... plaster ticked the boxes for me, but thanks for your input.

[@waskasoometalworks3329]

fair enough, mineral wool will definitely cut down the weight might try a combo of the 2! thanks

[@anthonyfletcher7663]

If you ad sodium silicate instead of water it will make it more heat resistance to the plaster

[@vogman]

Nice tip. Thanks for sharing.

[@andrisagita4808]

Anthony Fletcher i think, sodium silicate will expand

[@bryzabone]

What's with the huge crack in the lid gushing smoke and steam from the lid at the end?

[@vogman]

I don't think there's any huge cracks in the lid. There's a few rust-pin-holes as the original metal container was well rusted to begin with. When I filled the metal shell with plaster, I actually taped over the holes to prevent any seepage : ) Rust holes or not, it does a fine job. I'm very pleased with it. The steam isn't steam I don't think. It looks like it, but it was a very cold day when I filmed. There was actually frozen water in a bucket next to me at the time. Being daft (as I am) I actually put my hand in these "steam" clouds to see if it was hot (told you I was daft). Thankfully it wasn't. So it's a bit like seeing your breath on a cold day, but even warmer - condensation from the damp plaster drying off and venting through the pin holes. Hope this helps. Thanks for your question.

[@tomharrell1954]

Great video

[@vogman]

Glad you enjoyed it

[@owenquinn2161]

i have a question. when it comes to your oil burner does it have to be vegetable oil or can it be used motor oil? i can get large quantity's of motor oil for dirt cheap but not vegetable so i was wondering if it was a viable fuel source for my foundry. im using propane right now and its very effective but as said i can get motor oil for alot cheaper

[@vogman]

Hi. Personally I use veg oil in my oil burner but there's no reason at all why you couldn't substitute waste motor oil. I haven't used it personally but I've read about lots of folks using WMO. I hope this helps. Geoff

[@owenquinn2161]

VegOilGuy thanks for the reply and thanks for the great videos! they will help me save a good chunk of money I'm going to be making a foundry and a forge fueled by either wmo or wvo so it'll be carbon nutral and cost effective

[@pandupamungkaschanel8617]

Very good

[@vogman]

Thanks

[@poolbuilder27]

Ok, so im new to metal melting thanks to you and bigstackD and adrock. Lol.... Anyway, just curious about something. Why is air not a good insulator? Make one canister inside of a larger one. Nothing but void space between. Ive noticed the outside of my furnace (thanks Devil Forge) gets quite hot when melting. So it doesn't block the heat entirely. Ok. But air is a natural insulator,, so what makes air or empty space a less viable option. Just asking someone who knows much more than me. Thanks in advance.

[@vogman]

I'm not really up on my science Jimi, so it's a tough one for me. I'm aware air is a good insulator, but it's obviously not brilliant. If it were, we wouldn't feel the warmth off an open fire and we'd probably have a terrible time trying to cook anything 😁😁😁

[@poolbuilder27]

@@vogman This is true, but that air is also not contained the way it would be in something like this. Lol. The air current itself carries that warmth for us to feel. That being said, furnaces with some sort of air induction have a forced air supply. But since its contained, you dont really feel that heat unless you get near it. 🤣🤣 I love scientific debates.....lmao

[@flamingtoaster8707]

Would digging a hole and lining it with fire bricks work better?

[@vogman]

Any kind of insulation will provide an improvement, so yes you're right. The original foundries were earth and clay. There's a lot of guys like to stick to that style. As for fire bricks, again yes, they're great. I used them in my recent electric foundry build : )

[@itanc1]

Plaster and perlite 50 50?

[@xaragoth1]

What about just burying it in the ground, with a small trench for the burner assembly?

[@vogman]

It could work. I've heard of people having success with such foundry's and of course ancient foundries were lined with clay and earth, so it's an idea. Whether or not the insulation would be as good, I'm not sure. The plaster continues to impress me. There might be data like that out there but I'm afraid I haven't got it. Thanks for your question. All the best.

[@SomethingFromTheShed]

Hi vegoilguy I'm in the process of gathering things to make a furnace but I have a question. I have a steel outer shell and a inner steel drum the thermal barrier is going to be a mix of building sand and finishing plaster although I am stuck on the lid as I'm not sure how strong the mix will be as I think when I lift the lid it mite fall out. Can you help with this problem please ?

[@vogman]

Thanks for you question. Sand and plaster make a fantastic insulation material. I can melt aluminium and still touch the outside of my foundry my bare hands (not that I'd encourage anyone to try it). BUT this mix has no structural strength. Have you seen my foundry build - kzbin.info/www/bejne/pGWVpWaDZsuCr7s - I really think it might help you. There's also my web page - vegoilguy.co.uk/metal_foundry.php At the beginning of the video you'll see my plaster foundry, or what's left of it after a few uses. Steel as an outside shell should be fine. Anything on the other side of the plaster will be fine... I've got perspex : ) Steel on the inside next to the heat - particularly thin steel - it will begin falling apart very quickly. You'll have holes by the third burn if not the first. If you can, take my advise and forget the inner steel. Get some castable refractory. This is SO EASY to work. Like plaster, you add water and pour. But this is solid and stable. It withstands 1700C or higher without cracking. And it's not overly priced. It's more expensive than plaster... but it will outlast 100 plaster foundry's or more. You'll see all this in my video. If you're in the UK there's a link to a good supplier. If you're outside that, search the internet for a kiln or pottery materials supplier or similar. There's bound to be somewhere nearby. On the outside of the refractory, cast on some plaster insulation. You'll have a foundry capable of withstanding high temperatures without falling apart . Hope this helps. Any more questions, just give me a shout.

[@SomethingFromTheShed]

VegOilGuy well you see the inner she'll will be a calor gas bottle which is about 4mm thick. Out she'll is a beer keg. I'm in Merseyside. Where are you from as your accent sounds familiar

[@vogman]

Ah... in that case I'm probably do the same... just plaster. Those gas bottles are pretty tough. It should last you a good while : ) Where? Wolverhampton in the West Midlands. Not that far away from you really my friend.

[@SomethingFromTheShed]

Hey vegoilguy iv got some galvanised wire mesh which il make a frame out of for the lid then il secure it to the underside of the lid and then pour the mix in.

[@SomethingFromTheShed]

Yh not far from me buddu I'm over the water from Liverpool. Your the first person iv seen who melts metals in the uk. Il make a video and post it when I'm done

[@moonolyth]

galvanized mesh would be much better at 1, 2-inch squares. That plastic material could also have been heated in an oven then shaped.

[@ThePrufessa]

I always thought they were insulated with that starlite stuff. Or at least the homemade version of starch and water.

[@loganzister9344]

This still around and has the plaster crumbled at all?

[@vogman]

Yes, it's still alive : ) There are cracks in the plaster, but it's still holding together.

[@loganzister9344]

VOG thx u I think I’ll try this

[@tylerkrug7719]

Is the hard wall powder mix that your using, a fast setting type of joint compound? Like beadex makes 20, 40 and 90 minute mud, aka hot mud, same thing?

[@vogman]

Hi Tyler. In honesty it doesn't really matter. Most plasters have the same properties. The one I used took several hours to really firm up.

[@mikegunnellsministriesinc5384]

How long did this last you with the Plaster of Paris and sand mixter ?

[@vogman]

It still exists Mike : )

[@Civilsitis]

Why plastic of paris with sand and not some kind of fireproof cement ?

[@Jsellers1965]

How do you set up your end screen links like this?

[@vogman]

Hi John. Do you mean all the little video thumbnails? It can't be done any more. KZbin have pulled the plug on that. Sorry.

[@richardtheblue6294]

Is the outer insulation needed to reach high temp's or is it just something you felt like adding?

[@vogman]

Hi Kai. Thanks for your question. It was definitely required. Refractory is brilliant at dealing with heat and remaining stable, but it's not that good an insulator, so heat is lost. To retain that heat and make it work for you, you ideally need to insulate. I have been thrilled with the success of this insulation. It's so cheap and easy to do... just make sure it's on the outside of good refractory, otherwise it will fall apart : ) Best wishes Geoff

[@joeestes8114]

Great video!, you gave me some good ideas!

[@vogman]

Thanks Joe. Plaster really is a nice cheap insulator.

[@aronchas]

Hello there! I made a pizza oven with lava rock-cement-sand mixture. It has 5 inch thickness, I plan to use refractory mortar to insulate the interior. Whats the minimum thickness should I apply in the dome? I do not need more than 500C temps but I am afraid of cracks. Thanks for your kindly help

[@vogman]

Hi Aaron. Sounds like an excellent project : ) You're better off checking with the supplier about the thickness as products do vary. To avoid cracking, I'd recommend not rushing the drying time. Plenty of fresh air is best at the start I feel, and once it's dry, light a small fire - let it burn out and cool off. Light a slightly bigger fire - let it burn out and cool off. Repeat this several times getting progressively larger fires. This may take a few days but sometimes it's best not to rush if you want a nice result. Best of luck.

[@robertbailey9242]

Brillant!!

[@vogman]

Thanks Robert : )

[@NIGHTMARE-zy7tq]

Why not use fire place motor?

[@vogman]

I don't know much about that to be honest. It's certainly heat resistant, but I doubt if it's foundry-temperature resistant. Plus most importantly I'm not sure how well it insulates. If you have access to plenty and it ticks both these boxes, go for it : )

[@KOG005]

thx good work

[@vogman]

Many thanks : )

[@stromnessboy5171]

Great video, and an interesting test of another insulation method. I hope it enables you to melt higher temperature metals! All the best.

[@brightenhosie]

good stuff.

[@kennethkustren9381]

DIY REFRACTORY ... ?? SODIUM SILICATE SILICA SAND FIRECLAY & SLAKED LIME ... OR... PLASTER OF PARIS

[@MrFransie85]

Why not add a whole bunch of perlite?

[@vogman]

You could... it's all about options : )

[@KennethElstonBAK]

Wouldn't using thin tin be better than Perspex? I really have never heard of Perspex before, nor what it's used for and had to look it up to see what it is. It looks like Perspex is not used in the USA much, so what is it usually used for in GB? It looks and sounds and looks like what we (Americans) call Plexiglass. Which you can get in different thicknesses from paper thin to thick enough to stop a handgun round shot at it. Plexiglass will crack on on you very easy on you especially when trying to roll thin sheets like you were doing with your Perspex. I think that some thin tin, some sharp tin snips, and duct tape would have been much quicker and you wouldn't have to worry about it cracking on you no matter how rough you are with it during the build. If you didn't want to deal with the sharp ends of the tin that you have to watch out for; maybe use coroplast. Coroplast is fairly inexpensive easy to cut and will not crack. Also, depending on the diameter and temperature that you can get your foam cutter up to; you can also use your foam cutter to shape coroplast. Still a good vid and good build, thanks to you sir from across the pond :-)

[@maxlacarotte1489]

You should put réfractomètre brick instead

[@pandupamungkaschanel8617]

Great like

[@vogman]

Thank you! Cheers!

[@ronyerke9250]

When you get a few minutes, take a look at what rlbob1 did when building his furnace--3 sections! He also makes his own custom crucibles. He includes his chemical formula. He's not so well spoken, but has good information.

[@vogman]

Hi Ron. I've just had a quick look. He seems a very knowledgeable fellow. I must have a proper look when I get the chance : ) Best wishes, Geoff

[@ronyerke9250]

By the way, if you used casters with larger diameter wheels, you will have an easier time of rolling it around on your [not quite flat] surface. Your furnace may be a bit heavy to make that upgrade now, but you know best about that. I'm lovin' yet vids, keep 'em comn'.

[@vogman]

Thanks again for the tips and ideas Ron. Keep 'em coming : )

[@ronyerke9250]

VegOilGuy ok, you asked for it! I don't know how you protect your furnace from rain (and snow?), but if it's too exposed to the weather, you could turn over (upend) a plastic trash can (dust bin) and hold it on with bungee cords beneath to the rim. If here are no holes in the rim for drainage, they're easy enough to make. I'm not sure what perspex is, but it looks like what we call plexiglass here. You need to heat it to form it.

[@rodbennett4790]

Enjoyed the video but the boom boom boom in the music really put me off.

[@vogman]

Thanks for the feedback Rod. The good news is, I no longer use that particular track : )

[@danielcrawford7315]

@@vogman so boss been almost 2 yrs so I gota ask how is it holding up w youd plaster/sand cast?

[@vogman]

Hi Daniel. It's still fine - honestly. Sure it's cracked and nowhere near as pretty, but the plaster is CONTAINED outside of the refractory, so it's got nowhere to go and still does its job : )

[@danielcrawford7315]

@@vogman too kuul! Am going to be building a foundry in January and at $115 usd. For Mizzou it's far to expensive to use if there is a useable alternative for it...on the outside. Going to use the Mizzou for the inside and top coat it with ITC 100HT and possibly the other ITC PRODUCTS to top coat and coat the metal also. Just want to do it once lol as $ are hard to come by. Plan is to use forced air propane and possibly add the waist oil burner in too as I have access to literally hundreds of gallons of used oil thru the drilling rig moving company I work for...making that a free fuel source. Thanks for posting and your time to personally respond. Blessed days sirSir and a prosperous new year, Crawford out

[@joegomes4885]

I use 50% plaster of paris 25%sand 25% perlite. The water mixture 1 cup of bentonite clay to 1 gallon of cold water

[@cloud-forge]

foundry + molten metal + ... wood

[@DaveMalby]

Wood for a foundry? NOOOOOOOOO

[@vogman]

I know...crazy. And yet it's still there 😁😁😁

[@Jordan-rb28]

You're videos are awesome now but this is a horrible video. Plaster foundries are never worth it, spent a lot of money doing my first one even better than grants, lasted probably 30 hours but it's just not worth it after the cracking and crumbling! The even worse thing is that it takes 2x longer to heat all that mass and uses more fuel than a proper kaowool furnace. Its worth it and easier to do it right the first time!

[@vogman]

This isn't a plaster foundry - it's insulating the OUTSIDE of refractory cement foundry with plaster. The plaster acts as an EXCELLENT insulator as a very low cost. I've still got this foundry. It's still got the same plaster insulation. It's cracked but holding together as it's not directly in the heat : )

[@Jordan-rb28]

@@vogman the only thing is that the plaster is also a heat sink, similar to dense firebrick. As you said when you made you're electric foundry, air is an excellent insulator, so its better to have a thinner wall of insulation where there's not as much distance from the inside of the furnace to the outside, just from what I know. Cheerz