Refractory Coatings for Lost Foam Casting Patterns

[@thekekronomicon590]

This man is a saint for giving us all his secrets. I actually stepped away from the home foundry hobby 7 years ago just because the community was so toxic back then. People wouldnt share their refractory recipes or slurry recipes or where they bought their slurry from like you were taking food out of their mouths or something so you ended up wasting tons of time and energy and money just experimenting and trying to get usable tools rather than mold making and pouring aluminum and machining your cast parts. some of the forums that exist from back then are still safeguarding their little recipes but now they are completely irrelevant so I'm glad things have changed

[@johnallen8680]

100% correct ! Now with the arrival of affordable cnc and 3D printing the sky is the limit ! I'm just pissed about being 62 and having ailing health and mobility. So much creativity now available to me but I'm running out of life !

[@JulianMakes]

It’s true. One certain ‘gate keeper’ was particularly bad for this.

[@seahawkscram]

A true legend right there,answered all the questions that I had

[@kgeorgejunior]

This channel is underrated deserves a lot more attention!

[@smellsofbikes]

I asked a question over on another video and then I found this one, which answers my question over there. Nice work!

[@jamesmaclean2]

Hi Kelly I design & build Stirling Engines. I turn my cooling fins by hand on a lath and it is a Nightmare every time! I wish I had seen this 40 years ago ! This is amazing to me & you are doing it in your Home Shop! WOW Thanks for sharing all of this. James

[@kellycoffield533]

Turning fins on a lathe is like a perpetual exercise in parting......takes a good lathe and great tool. Best, Kelly

[@brucewilliams6292]

I can't thank you enough for your generosity in putting these videos together. I was thinking about converting my milling machine to CNC to make complex parts but after watching your video series, my mid-weight CNC router will handle the foam cutting and the lost foam cast will get me what I want. I have done sand casting before with great results but hated dealing with the sand and keeping it mulled. Excellent video. I see 10k plus subscribers in your near future!

[@kellycoffield533]

If you already have a CNC router and proficiency with CAM, Gcode and a good post processor, you'll be starting miles ahead of where I did. Glad you found the vids helpful. Happy casting. Best, Kelly

[@Symbio1]

Thank you so much. You are so generous with your detailed info. I love that you mention the joint compound as a substitute. You are the best!

[@henrycowdery2688]

The quality of your casts is mind blowing! All your videos are packed with great info, thanks for sharing your experience and knowledge.

[@donaldsutherland244]

Thank you! I make scale models and this will definitely help me!

[@allana5708]

Nice video of the coating process and your insights using different processes. Your experience is very helpful.

[@zekestrom]

Excellent video with unusually clear information about products used and how you used it.

[@kellycoffield533]

Thank you zekestrom. Glad you found it useful. Best, K

[@monk8235]

Thank you for advice on drywall coating! I'm experimenting with that now.

[@gwheyduke]

All good videos for sure. I'm having a little problems with the sound even with my speakers up full volume. Otherwise excellent information.

[@casthc6795]

hi, do you have any lost foam question

[@mvzuneta4563]

Que espuma e estra por favor onde encontro

[@craighoward3794]

yeah sound is a little low for me too

[@ovalwingnut]

Insightful and magically stimulating :O) You "are" the refractory whisperer. Thank you!

[@RoadsEndGarage]

Great channel!

[@maddyjo9130]

Good content

[@TBJK07Jeep]

Thank you for putting this together. I enjoyed the video & look forward to learning more from your other videos.

[@keithnoneya]

Love the video's Mr. Coffield, I'm learning quite a bit. Thanks for sharing your knowledge. Best Wishes & Blessings. Keith Noneya

[@johnjackson8561]

Awesome information! Thanks 👍

[@timothyehook4883]

Thanks for all that great information Kelly..👍

[@maloyaircraft1174]

Amazing content! Thank you for posting

[@thomashoffmann4504]

Thank you for sharing technical facts!

[@stevesrt8]

I'm one of those guys on you tube that cake on too much and have been struggling with bubbles. This information is gold. thank you so much. I can't wait to try using the dish soap. I was having venting issues but it turns out i was putting it on too thick. thanks you Sir.

[@kellycoffield533]

Thinner coating will help. Saw you recent vids for coin casting molds and plaques. You're on the right track. The one for your nephew that had the defect was because the sprue and contact area were too small for the pattern and couldn't feed it fast enough to prevent partial mold collapse. Best, K

[@stevesrt8]

@@kellycoffield533 thank you Kelly. Cool. that makes sense. I appreciate the reply. cheers

[@casthc6795]

hi, do you have any lost foam question

[@rexmundi8154]

Brilliant! Such great work.

[@evanlane1690]

For the joint compound route, can you thin it down so you can do something kind of like a dip? Edit: Never mind. Didn't get far enough into the video. The answer is yes.

[@alejandroluer]

Amazing!!!! Thank you so much!!!

[@prestonengebretson2920]

Wonderful video Kelly with lots of great information...you have got me now wanting to get back into casting...Looks like I will need to watch most of your videos...I use to teach Lost Wax casting at the Glassel School of Art in Houston, so with your new info I should be up and running in a short time...I would like to make some aluminum uprights for the front suspension for a Stylized 1923 Bugatti type 32 roadster I am building...thanks for the timely find of your series...

[@kellycoffield533]

Glad you found it helpful. With your past experience it should be a much shorter learning curve. Structural parts like uprights deserve design conservatism. Get your process down then enjoy being able to place metal where you want it! Best, Kelly

[@casthc6795]

hi, do you have any lost foam question

[@samueltaylor4989]

The one big issue using drywall compound is that it will eventually turn fowl by bacteria and mold growing in the compound especially when you mix in water, it will pull in spores and bacteria from the environment. It will last a while but does have an expiration date.

[@kellycoffield533]

Haven't had that problem but if so, a teaspoon or two of bleach will fix it. Best, Kelly

[@TravisFabel]

Thank you for the helpful video. I finally find somebody who I really want to hear on KZbin, and their audio is very quiet and hard to hear. Lol

[@kellycoffield533]

Yah, I'll work on that but in the interim, it's easily heard by turning volume up on the YT viewer & your device, at least that's so on my phone, tablet, and LTPC that is the case with and without ear buds. K

[@casthc6795]

hi, do you have any lost foam question

[@truethought369]

When you have wet slip in hollows, after mopping out with a brush, could you use a hire drier on low heat to finish drying the part? This is very interesting and thank you.

[@cerberus333dog]

useful information! Thanks!

[@michaelmcbride5064]

Thank you so much for your videos on lost foam casting! I got so excited about the possibilities that I bought a pin router for future pattern making. I sure hope you made (or will make) a video showing how you made the big, complicated intake manifold pattern. Do you use a lower temperature hot glue to assemble the pieces, or some type of regular glue? I want to eventually use your methods to make some finned valve covers, oil pan, and maybe an intake manifold for a hotrod project I'm working on.

[@kellycoffield533]

I do have several videos in the works I'll post in the very near future that will address your questions. Pin routers are very versatile machines, and an excellent alternative if you're not a CAD/CNC guy. With the exposed cutting bit, pin routers are a serious threat to the operator so give it due respect and make fixtures where necessary to keep you hands out of harms way. Best, Kelly

[@casthc6795]

hi, do you have any lost foam question

[@makingcookingfixing]

@@kellycoffield533 Much respect Kelly, did you make a video that explains the gluing part? Thank you!

[@kellycoffield533]

@@makingcookingfixing kzbin.info/www/bejne/imOraYh-aLmYl68

[@Biokemist-o3k]

Wow! I am just. getting into casting for parts on engines and equipment that is obsolete. Just fantastic results my friend. You do some incredible work. I do not have a cmc or a milling machine but I am just starting to build one. thank you. Are you here in PA or are you somewhere else? You are really tan so maybe Florida?

[@temporalmadness3756]

Would it help to add a source of vibration, like an orbital sander, underneath the coating bucket to eliminate any undesired cavities?

[@joelglaze5545]

That intake would be interesting with up to date injectors made into the cast send me a check for the idea 😁

[@mihoubiali1402]

Tell us what Kind of coat or how it's prepared

[@حامدنامة]

افضل قناة في هذا المجال جميل جدا جدا ممتاز واصل.

[@kellycoffield533]

سعيد لأنك تجد أنه من المفيد

[@Ak47ram]

@@kellycoffield533 love taking the time to reply in Arabic.

[@abyssalblue3089]

Have you attempted Spraying Refractory Coating on Larger Molds? Something like an industrial airless Paint Spraying System?

[@kellycoffield533]

Never tried that. Best, Kelly

[@learningtocrash4030]

I was hoping he would turn the manifold a few times after dipping it to get a full/ uniform coating when i saw the slurry pour out when he tilted it.

[@DavidSmith-xb8qj]

This looks awesome. But the sound is low and we are missing a lot

[@en2oh]

Given your experience, how do you feel about ‘burning out’ PLA/Wax forms for lost resin casting? Is it really necessary? (Btw, polypropylene glycol has surfactant properties but propylene glycol is a different agent altogether.)

[@kellycoffield533]

PLA/Wax/Foam are all evaporatve pattern casting processes. I like lost PLA/Wax/Resins for highly detailed small parts like jewlery and ornamentals but lost foam is so much more economical and practical for larger parts because the mold media and pattern material are a very small fraction of the cost, not to mention the large difference in labor to make an investment or shell mold versus just vibrating loose sand, and then the need for a very large oven and energy cost to burn it out. For a part like one of my automotive intake manifolds, it would be 300-400lb of shell or investment and take days or a week to burn it out. To demold, in lost foam I just dump loose sand on the ground (which I can reuse) and pick the part out instead of hours of chipping away and disposing of 400lbs of investment or shell. Not sure where you're going with PPG vs PG comment but I said what I meant. I use dilute Dawn dish washing detergent because one of the active ingredients is propylene glycol, along with other surfactents, costs pennies, and is much more benign than ethylene glycol. Best, Kelly

[@johnoler357]

Until I happened upon your video, I never knew such a craft existed. You get crazy good results with your methods. Is this method good for cast iron exhaust manifolds for antique engines?

[@kellycoffield533]

Yes, most lost foam casting done in industry are iron lost foam castings. Best, Kelly

[@AlecMakes]

Aways great videos Kelly with invaluable information! One question is in this video you mention as an alternative dipping slurry to use light weight non-setting drywall compound but in your earlier video about a year ago when you were casting the saucer cup and spoon you mentioned to use non settings drywall compound. Is their an improvement using the light weight non-setting drywall compound over the regular non-setting drywall compound or will either work just as well?

[@kellycoffield533]

I'd imagine either would perform about the same. I had the lightweight stuff on hand. It may have a slight advantage if the lightweight filler is more porous, but other than that, I think either woul dbe fine. Best, Kelly

[@casthc6795]

hi, do you have any lost foam question

[@sierraecho884]

I would like to test out a mix of plaster + silica sand in thin coats brushed on on the master. After the first coat i want to use steel wool to incorporate into the next coat and then just pour the rest. What do you think ?

[@kellycoffield533]

Reinforcing the coating is not necessary in lost foam casting because it is used to control the escape of evaporating pattern gases and improve surface finish, but not used as structural mold support. That purpose is served by the compacted sand.

[@kellycoffield533]

@@sierraecho884 OK, that sounds more like investment casting. Precoating is common, as is adding silica to the plaster. I dont do much invetsment casting but friends that do larger castings just use wire/fencing as reinforcement cast/invested in place in the outer diameter of the investment.

[@sierraecho884]

@@kellycoffield533 Thank you for the quick response. You work is great btw.

[@allenmitchell5893]

Dear Sir: I am thinking of making my lost foam pattern for an engine block. So my question is: How do you account for the shrinkage after the part is cooled. How do i cut my patterns to account for this shrinkage??

[@kellycoffield533]

Assuming it's aluminum, you should make your pattern 1.3% larger in all three axes. In other words, multiply the dimension for the length or location of each feature/location by 1.013. Best, Kelly

[@froat1]

Would pre-dipping and letting those somewhat weak runners dry give them a little more strength to aid in the handling?

[@kellycoffield533]

I do pre-dip the sprue seperately and attach it when molding. I do modify the gating at times to make it strong enough to handle when dipping. The coating can be poured, ladled, or brushed as well but dipping is so fast and produces such a uniform coating it's hard to beat if you have thefacility for such. Best, Kelly

[@rubenmanzione]

Hola soy de buenos aires argentina,cómo está compuesta la lechada dónde sumergen los moldes...no encuentro información sobre eso...excelente video muchas gracias!!!

[@kellycoffield533]

No tengo la composición del recubrimiento como lo compré, pero si buscas en mi canal, tengo un video sobre este y otros recubrimientos. Saludos cordiales, Kelly

[@rubenmanzione]

@@kellycoffield533 muchas gracias x tu atencion ;)

[@ALANCREA]

Hi Kelly i have signed up on the The home Foundry a few days ago but im still waiting for confirmation ( Your account is currently awaiting confirmation. Confirmation was sent to ) but nothing has been sent to me ? i have a question as i live in Norway we dont have the powder dry wall none setting joint compound we have some ready mixed stuff when looking in the data leaflet what should the main ingredients be in it , as i should look for as we have no refractory resellers here 😞 your videos are great keep up the good work 🙂

[@kellycoffield533]

What is your user name? I'll watch. Sometimes our software will flag an IP address as a spam source and that will cause rejection. Drywall coatings are mainly, plaster of Paris, gypsums, and small amounts of clays. If it's ready mixed, it is non-setting. The pottery hobby may have similar refractory materials. Also companies that service boilers. For lower temperature metals, some European hobbyists have used Wytong brick as furnace refractory. Best, Kelly

[@ALANCREA]

@@kellycoffield533 my The home Foundry user name is ( acr ) thanks for the reply and info 🙂

[@kellycoffield533]

@@ALANCREA You'll need to re-apply. Best, Kelly

[@joesask857]

thanks man

[@goustavonana2930]

I have a question, how with one layer of ceramic and without covering the sand does not crack, I use several layers and sometimes cracks occur

[@kellycoffield533]

Must be the type of coating you are using. This coating is not the type used for ceramic shell casting. Best, Kelly

[@goustavonana2930]

@@kellycoffield533 Thanks for the reply. What are the ingredients that go into this paint and their amounts?

[@goustavonana2930]

@@kellycoffield533 Your paint can be used with models that come out of a 3D printer

[@kellycoffield533]

@@goustavonana2930 No. Coatings for 3D printed patterns are intended to become hard structural mold material. Lost Foam coating is not a structural part of the mold. It merely serves to replicate the surfcae finish of the foam pattern and act as a permeable layer between the pattern and mold sand to control the rate of escaping gases. Best, Kelly

[@kellycoffield533]

@@goustavonana2930 Probably too involved of a discussion for a YT reply but if you are casting aluminum, try using thinned dry-wall joint compound. It works well. The light weight non-setting variety is best and contains many of the same ingredients of commercial lost foam coatings. Best, Kelly

[@andrewatchaboy2762]

Would the drywall slurry would work with PLA parts?

[@kellycoffield533]

Not sure what you mean. Lost PLA would use investment casting not the lost foam method. PLA will cannot be evaporated by the molten metal during pouring. It's too dense. It must be invested and burned out of the investment before casting to remove the pattern and cure the investment. Though many investments are plaster like, they have other ingredients to improve strength and permeability after burn out. Best, Kelly

[@andrewatchaboy2762]

I meant using the drywall coatings in the same way that ceramic coatings are used in the lost wax method. This would consist of repeatedly dipping the pla object into the joint compound, burning out the plastic in a furnace (leaving only the shell behind), and finally pouring the molten metal into it. I was actually able to test this possible method during the past week and found the following: 1. Using a foam riser gives the plastic room to expand but there still tends to be cracking and breakage along edges/corners. Adding sand did help a little bit but having lots of ventilation is the key. The breaks are usually very clean breaks and can be repaired quite easily with more slurry followed by a subsequent firing. 2. Painting on the first coat works best in order to capture small details (if you need it) and for ensuring total coverage of the object. Air bubbles still pop up despite dipping the object in surfactant beforehand, running it all through a vacuum chamber, and adding soap to the slurry. 3. The biggest problem is the insulation with the empty shell. Transfer time form the furnace to the sand needs to be extremely quick to minimize heat loss and even then it’s still too cool half of the time. This method is much less forgiving than the sand and plaster method which stays hot for longer periods of time even in the open air. All-in-all, I would say this method has great promise and I will be experimenting with it further.

[@kellycoffield533]

@@andrewatchaboy2762 Apples and Oranges. The coating in lost foam casting serves as a permeable barrier not as structural mold. Best, Kelly

[@vernm6189]

What Ford Engine is the intake Manifold for??

[@kellycoffield533]

1969/1970 Boss 302

[@marciomila9264]

Qual material uza para mergulhar as peças para fundir esse produto verde

[@kellycoffield533]

If I understand correctly, you are asking what I apply to the foam pattern before the refractory. It is a 1/2 teaspoon of liquid dishwasher soap ("Dawn brand") in a gallon of water. The anti-spotting agent is Propylene Glycol which acts as a surfactant, reduces surface tension, and makes the refractory wet the foam without bubbles. Best, Kelly

[@marciomila9264]

@@kellycoffield533 ok seria sobre esse refratário do que ele é feito

[@ouadjenetach5576]

ماهو المحلول الذي غطست فيه القطعة

[@madlankan6735]

Mr Kelly ! I have been making my foam modules by hand (please watch my video called Lost foam casting a crank case of paraglider engine). Can you show your milling machine clearly in a video

[@casthc6795]

hi, do you have any lost foam question

[@madlankan6735]

@@casthc6795 yes 1 I dont know which kind of Aluminium raw metirial should be used(I am using scraped brake parts) 2 I want expidite modle making with foams.and I want to know should my casting to be heat treated or not .thanks for asking help

[@kellycoffield533]

Hi MAD, I commented on your video. I'm mostly using a CNC router now but try viewing my video "Carburetor Main Well Foam Pattern". It shows what can be done with hand guided pattern routing with wood working tools. Best, Kelly

[@madlankan6735]

@@kellycoffield533 yes thanks Mr Kelly.I watched your video.l think my main disadvantage is using expanded polystyrine.and i,ll use router soon.thanks again for watching my video

[@kellycoffield533]

@@madlankan6735 I have found the extruded PS to machine and finish better. Expanded Polystyrene packaging can vary widely in density, but can also be sanded for improved finish and appearance. Higher densities machine and sand better at the expense of more material to vaporize. You can use your hot wire to pattern cut foam with a simple cardboard template. I show this in one of my videos. If you reduce the length of unsupported wire it will improve accuracy, but you are limited to 2D pattern parts. Patterns made with template guided router cutting can be 2.5D and will generally be more acurate and repeatable. Best, Kelly

[@rahatali6568]

What is refactry sllury

[@kellycoffield533]

Refractory just means ability to withstand high temperature, but the slurry is a coating that preserves the surface finsih of the pattern and allows the evaporated foam gas to escape at a controlled rate. Dryawll/Gypsum/Plaster mixtures work for lower temp alloys. The more refined commercial versions are usually Mullite/Alumina/Zirconia mixtures with clay binder and additives to keep the constituants in suspension, self-level, and wet the pattern better. Best, Kelly

[@RobertLBarnard]

I can't hear you.

[@WireWeHere]

The Dawn of Casting From the Dawn of KZbin, I began to wonder. Why Dawn or Dawn Dish Soap, not Madge with her druthers. Dawn's mentioned so often, it's ironic and funny. In surfactant up castings, Dawn's damn rather punny?

[@vizagothx7294]

do you maybe have a fund to buy a decent microphone?

[@qivarebil2149]

If You fix the sound of Your voice, I'm sure this would be a great channell to follow...

[@georgeingram3150]

You are inaudible. Other videos on youtube are fine

[@kellycoffield533]

KZbin eliminated the ability to edit audio volume on an uploaded video. It may be inaudible at the default YT loaded setting but far from it if you use your volume controls. I can easily hear it on my phone, tablet, & computer.

[@jerryplumley1576]

You need to upgrade your microphone, you're hard to understand . I want to hear everything you've got to say .

[@TheJohndeere466]

I have been watching a lot of your videos and you do very nice work. I was wondering what you do for a living. I am machinist and I make a lot of parts for pulling tractors. Now am trying to make a pattern to cast a new head for a tractor. I am making it from wood. I also will need a new valve cover because the head will be a little wider than a stock one. I thought about making this from aluminum and using the lost foam method. Years ago I made an aluminum intercooler using the lost foam method. There is a place close to me that 3d prints cores and molds out of sand. I think the machine lays down a layer of sand but only applies binder where you want a core or mold. Here is a video about the company kzbin.info/www/bejne/mpa5fnmnj9Ggi80

[@kellycoffield533]

IMO, lost foam is far more practical than conventional hard pattern sand casting for making one-offs, and small quantities, but sort of depends upon what you are set up to do. After you get your processes sorted, it becomes all about the pattern making, but best to work with some simple projects before attempting a pattern where you've invested a lot of time. Best, Kelly