Pattern Materials for Lost Foam Casting

[@bluewhaleadventures152]

Just stumbled across this channel and it’s the best thing that’s happened in a while. These videos are unassuming yet information packed. Thank you for the along the time to create and share.

[@benduncan3930]

I just got more useful information of what to use and not to use from this 24min video than I have from the hours of videos I’ve watched on this subject. I’m new to this.

[@Biokemist-o3k]

Excellent video my friend!!!! Thank you for sharing your wealth of information.

[@MrMamalli]

I thank you from the bottom of my heart for your quick response. I hope you are always stable. The world needs people like you. With all due respect and thanks again.

[@timothyehook4883]

Hey there Kelly! Thanks for taking the time to answer the comments and questions...that's great of you. ...so we learned here, both densities of foam and gypsum drywall compound, worked up with water, will make a decent go at it...no complicated gating system or venting is needed..just dump it on there and let it do it's thing!... that's fricken awesome. .thanks for the other thoughts and wisdom too...☮️👍

[@willywgb]

Hi Kelly Thank you so very much for all this information on lost foam pattern making. There is allot of excellent information here and also in your other installments on this subject. Years of Testing and trying different products and fine tuning to end up with what works for this type of work. Looking forward to your next video. Cheers Willy

[@RUSTICW0LF]

Thank you my friend this was so helpful for a newbie like me, just about to start having a try at this technique . Big thanks for the urethane foam tip. I was about to cast some rubber moulds to cast 2x part urethane parts in. (for repeated consistent models) New sub for sure.👍

[@John____Smith]

Thanks a lot for you that share yours experience!

[@donaldsutherland244]

Thank you for this, I found some very useful ideas! Thank you!

[@russrawley6712]

You've obviously got great skills and the process looks amazing but I've only just found your site but I think you definitely need a collar or lapel mic cos we can't hear you .still good to watch though 😉👍

[@gregkretchmer3588]

I use lost wax quite a bit, and found you can melt a block of paraffin and cut up a plastic bucket (5 gal type) and add by weight a ratio of around 1 to 4 plastic to wax, let it cook until the plastic resolves, stir it up really good, let it harden and it makes a carvable wax, kind of soft. It shrinks a little as it hardens, you have to work with the ratio to get the lowest expansion rate, but it works, using plaster with a can to hold it together as it burns out, and its cheap. Do it way outside if you try it, it is flammable. The rest of your stuff is good stuff. Cant wait for the snow to melt...

[@kellycoffield533]

A lot of people tell me I should be using lost wax or PLA, but unless you’ve used both processes, you wouldn’t fully understand that every process has its place. I use lost foam because I primarily make one-off or low quantity automotive and machine parts. IMO, lost foam requires significantly lower material and labor cost than lost wax and as parts get large, this difference becomes even greater. The same is true for lost PLA whether block investment or shell. Foam is much less expensive than wax for patterns but the biggest differences come from what it takes to make the mold and claim the casting from the mold. For a lost foam mold, I literally pour dry sand into a barrel around the pattern and vibrate it. It usually takes 5-10 minutes and I do it while the metal is melting. To demold, I simply dump the flask/sand on the ground, pick up the casting, cool it in a bucket of water, and nearly all the refractory coating (applied in a single dip coating) just falls off. Any remainder is blown off in a minute or two with compressed air. Keep in mind the molds for my parts are typically between 75lbs and 450lbs. Dry sand mold material is $20/ton, but it’s completely reusable (no disposal cost) and requires no special treatment other than keeping it dry. Then I just shovel the sand back into the flask through a sifting screen for storage and next use. Now imagine the equivalent cost and labor for block or shell investment; the cost and work to prep that much of investment, invest it, fire it, (yah, fire 450lbs of investment!), the apparatus required to heat and handle that large hot mass, and then chip away the clinging mold to claim the casting. It’s just no comparison. Now for small parts with fine detail and repetition like jewelry or artwork, lost wax is my choice. Best, Kelly

[@peterkolev8571]

Thanks for sharing your knowledge with our thirsty minds. Of all different casting techniques, i like this one the best. I need to cast a practical part that will need to retain the mechanical properties of the original aluminum. However, i don't know if lost foam method would contaminate or cause porosity in the cast. What is your experience on this? What happens to the resulting gas in the process?

[@kellycoffield533]

IMO, casting design, feed system design, and melt management a far greater factors in obtaining a casting with good material properties rather than the use lost foam or conventional sand casting process, especially for a non-professional hobby caster. Of course, you need to start with a known alloy, but even then, hydrogen porosity is the most common source of degradation of aluminum mechanical properties. The decomposed polystyrene gases resulting from the LF process are not soluble in molten aluminum. In general, permanent mold casting alloys and processes can achieve better mechanical properties than sand casting processes. Casting alloys will never achieve the mechanical properties of wrought alloys. Best, Kelly

[@truethought369]

Thank You for this very interesting info. I would like to make a small 4 stroke engine, to start with! If I am successful, I have a V-Twin design, that needs to be made. I will keep looking at your vids for more info, Thankyou.

[@حامدنامة]

قناة ممتعة مفيدة جدا .كثير من المعلومات القيمة والعملية رائع واصل.

[@kellycoffield533]

أنا سعيد لأنك وجدت ذلك مفيدًا. شكرا لك على النشر

[@davemartin2810]

What a HUGE wealth of information! Thank you! Love your channel. One question: I have a few custom parts I'd like to have cast for my boat in silicon bronze but have little interest in acquiring all the tools to actually melt metal and do the actual casting. If I was to make patterns out of foam using these techniques would a foundry consider pouring the metal for some one off parts? Or do you think I'd have to go so far as make the container, vibrate the sand, etc and then deliver something like that to a foundry? Anyway, excellent channel!

[@kellycoffield533]

Unless you have a personal relationship with someone at the foundry, I'd say very doubtful. Most foundries will have no lost foam experience whatsoever and even so most want production work and dont want to mess with individuals. I think best bet is to find a small one man foundry or do-it-youselfer that has SiBr casting experience. Best, Kelly

[@WireWeHere]

It's better to ask in the winter. My friend walked in the first place in the yellow pages. Started to tap his feet at the door and wound up on his ass with one of the Hobie molds cushioning his fall. They were very accommodating and symbolically slipped his parts in at no charge. The rudder stabilization fins worked well for a prototype and frozen snowmobile boots on advertiser's fancy water catch mats don't stick together worth shi... .. .oww. Bounced back, twice. It never hurts to ask? Cheers.

[@tomsmith3045]

This is great info! Have you tried 3m foam safe spray adhesive? I think it's their number 78. Asking because I believe some model makers are using it for foam laminations of the pink foam to make aircraft wings, and it's supposed to hold up pretty well. If it's a thin film, I'd think it would cause less problems with the routing. For them, they use hot wire cutters and I guess it works just fine with hot wire cutting.

[@kellycoffield533]

It works fine for sticking foam together and it can be cut with a hot wire but its a sticky mess if you touch the joint with a router bit or sand paper........instantly loads the bit and will ball up and not sand evenly. Best, Kelly

[@mustafagbar2304]

Which type of foam use for casting aluminum

[@JaapGrootveld]

Tanks...

[@85rocco]

Hi Kelly, do you think adding a little WaterWetter to the joint compound coating as a surfactant would be of any value?

[@kellycoffield533]

Maybe. I don't know what the active ingredients are but if it is surfactant in nature it should be helpful as long as it is not reactive with the coating. Best, K

[@MrMamalli]

Greetings and thanks for the beautiful video, I respectfully request the name and type of foam you used. What kind of foam can I use in Germany? Thanks again

[@kellycoffield533]

I use Owens Corning Foamular 150. It's (pink) extruded Polystyrene Insulation board 1.3lb/ft3 density available in home improvement stores in the USA. I'm sure there must be the same or equivelants in Germany. Best, Kelly

[@MrMamalli]

@@kellycoffield533 I thank you from the bottom of my heart for your quick response. I hope you are always stable. The world needs people like you. With all due respect and thanks again.

[@jamesdond1]

Can you use the can foam or the pour foam into a mold to make the foam pattern?

[@kellycoffield533]

My answer would be no, I wouldn't recommend it because 2-part foams are thermosets (usually urethanes) not thermoplastics (usually polystyrene), and they tend to just decompose to ash and solids as opposed to melting and turning to vapor, which is important in producing defect free lost foam castings.....but, I have seen some castings on YT that used such. However, they didn't look like an acceptable result by my expectations. Best, Kelly

[@lukebranco3685]

Thank you that was very interesting and informative. I need to cast an old ornate air cooled moped head. Where are you located? Do you take jobs? I would eventually like to cast myself but, its going to take awhile to get all the supplies needed.

[@kellycoffield533]

Sorry Luke, too many of my own projects to attend to.....it's hobby not business. Best, Kelly

[@masterspin7796]

You ever try rubber glue?...it only sticks to rubber glue I use it on my Table Tennis rubbers to hold the foam backing onto the wood blade...

[@kellycoffield533]

Not sure what you mean by rubber glue. For gluing rubber? Contact cement? The solvent in the glue cannot attack the polystyrene foam. That eliminates a lot of candidates. The foam safe contact cements are essentially latex. They work, but still wont dry on the interior of large surfaces if you are laminating and they stil gum up a cutter. Best, Kelly

[@madlankan6735]

Sir 1 Can we dilute shelak & what kind of alchole to be used 2 Can we use water base wood polish as smooth surfant

[@kellycoffield533]

I use denatured or isopropyl alcohol to dilute shellac because I have it. I don't know about water based wood polish, depends if the other ingredients can melt and burn out cleanly. You'll have to try and see. Best, K

[@madlankan6735]

@@kellycoffield533 Thank u very much

[@manitobaman5588]

Please talk about the poisonous fumes from melting foam.

[@kellycoffield533]

They are toxic like most anything else that is a byproduct of combustion. Use common sense, cast outside, don't breath in the fumes, and if you think you cant accomplish that use a respirator. Toxins unlike poisons have tolerable exposure limits TLV. Hard to know where your at on that scale but for infrequent exposure the threat is small compared to other things you encounter every day. For small pours in 5 gal flask I can easily avoid any fumes. For large pours I will use a respirator, especially when demolding. If you are uncomfortable with that, simple, just dont do it. Best, Kelly

[@malakiblunt]

another good solution for laminating large areas with the thinest possible glue line (and also as a general instant adhesive) is mounting film it works just like double sided tape only theres no tape just 23um adhesive film -ts called - neschen gudy and is marketed for photo mounting you can get it in permanent and repostional versions in any width up to 6ft - downside not the cheapest

[@kellycoffield533]

Thanks Philp, I'll have to look into that. I suspect it may still load up cutters and abrasive but so does most everything else. The most promising glue for laminating was Cyanoacrylate/CA, because it was chemically activated, could be applied very thin, and cured hard enough to be machinable, but my hopes were dashed because the solvent/propellant in the spray activator aggressively attacks the foam. I occasionally come across come CAs that say they are foam safe but they are very expensive. If anyone knows of a foam safe CA I'd be eager to give it a try. Best, Kelly

[@kellycoffield533]

......I completely forgot to mention Polyvinyl Alcohol (PVA) for laminating. It takes a while to dry when laminating large areas but works pretty good and less prone to loading cutters. Downside is it can get thicker than desired if applied to a machined surface. Works better on the smooth undisturbed surface of a XPS plank. Best, Kelly

[@dave_ecclectic]

@@kellycoffield533 What about the baking soda/ CA stuff. I checked, baking soda dissolves in alcohol. The powdered surface after drying was delicate but its only needed to apply the BS to one surface. I suppose if you need a stronger bond a very slight amount of shellac might work.

[@kellycoffield533]

@@dave_ecclectic Is the NaCHO3 the activator for CA or a filler? I've recently found some more reasonably priced foam safe CA products I'm going to try for laminating. The model airplane and rocket hobby sites usually have good sources. Best, Kelly

[@dave_ecclectic]

@@kellycoffield533 Not Nachos, baking soda. It acts like an activator although is is a filler too. You should try it just to try it. Its an interesting affect. Put a drop or so of CA down and push some nachos into it.

[@madlankan6735]

Mr Kelly ..How can be reduced the brittlness of castings.

[@kellycoffield533]

Hard to say if you dont know the composition of your casting stock, but many metals are soluble in aluminum and above small levels reduce strength and elongation. If you use a steel crucible (as opposed to clay/graphite), iron contamination could be the culprit, or if you use your crucible for other metals, that can be a source of contamination. Small amounts of copper or chromium will embrittle Aluminum.

[@madlankan6735]

@@kellycoffield533 Thank you Mr Kelly .after your advise I stoped using steel crusible .but the brittlness same as before .

[@michaelmcbride5064]

OK Kelly, I give up....I have tried everywhere I could think of to find "non setting drywall compound". It seems to be non existent? Can you be more specific on the type or brand of compound you are referring to? I have everything I need to duplicate your casting process shown on your you tube videos except for the coating slurry.

[@kellycoffield533]

Michael, it's light weight joint compund for drywalling and any home improvement (Lowes, Menards, Home Depot) store will carry it. I used USG Sheetrock brand but that doesn't matter. Buy the premixed kind in a pail. You may have viewed it already but I have a video entitled "Refractory Coatings for Lost Foam Casting Patterns" It has a link to a Web Forum thread on the subject with more discussion on use. Just thin it to either a brushable or dipping consistency. Best, Kelly

[@pasqualesgro]

Ciao Kelly Could you advise me on some material to use in place of the refractory paint? is liquid chalk okay? which one would you use if you didn't have the right paint? Thanks and best regards.

[@kellycoffield533]

If you are casting aluminum or non-ferrous metals, I'd suggest drywall joint compound. In the US, gypsum board is known as "drywall". The non-setting lightweight joint cmpound is best and available in the home improvement stores. Just thin it (with water) to the deisred consistency for brushing or dipping. It only needs to be a thin coat on the pattern, not a built up thickness. If you have colored foam, just enough to turn it white. It's purpose is to reproduce surface finish of the pattern and provide a permeable coating to control the rate that the evaporating foam gase escapes, not to bemold support. Best, Kelly

[@pasqualesgro]

@@kellycoffield533 Thanks for the comprehensive answer, you are a very helpful person and a gentleman. now I understand the meaning of refractory painting. Thanks again and my best wishes from Italy.

[@kellycoffield533]

@@pasqualesgro Felice che tu l'abbia trovato utile. Alla prossima volta amico mio. Kelly

[@stevesrt8]

I wish i seen this video a year ago. i've been having trouble with gluing the spruce on. My glue gun gets too hot and it melts the foam. I've also tried laminating foam and got my endmill gummed up. Thanks for the tips. I'll have to try and find some of that tacky glue.

[@kellycoffield533]

If you install a dimmer switch ahead of your glue gun you can use it to control temperature on most hot melt guns because they just have a resistive heating element. Just make sure the dimmer is suited to the current load. Best, Kelly

[@kellycoffield533]

On laminating, try shellac or polyvinyl alcohol. Best, K

[@stevesrt8]

@@kellycoffield533 that's brilliant. cheers

[@albertreed966]

i hink that this would have been very interesting UT, the sound was TERRIBLE !

[@kellycoffield533]

Don't worry Albert, because if you can't locate the volume button on your device your chances of ever successfully casting anything are about nil, so nothing lost.